tag:blogger.com,1999:blog-55171760128615505892024-02-19T18:17:48.504+11:00EdiacaranChris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.comBlogger175125tag:blogger.com,1999:blog-5517176012861550589.post-91618647223729343182012-03-04T14:26:00.000+11:002012-03-04T14:26:32.769+11:00Seeing the Forest for the Trees<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhbOpDLHRdIKqiBgLh_aPMrSGg0bAXYCgVLiuFWN0o5EvsJAVGPkXgxDiKldK7GnTTHE76DRaknQonbulZrN_MyJGk5EdjhWxF-nAzZMIDa-EniRWQolu7q53ig5gOlH0t45QTJoT1dvgpb/s1600/Tailyuanforest.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhbOpDLHRdIKqiBgLh_aPMrSGg0bAXYCgVLiuFWN0o5EvsJAVGPkXgxDiKldK7GnTTHE76DRaknQonbulZrN_MyJGk5EdjhWxF-nAzZMIDa-EniRWQolu7q53ig5gOlH0t45QTJoT1dvgpb/s320/Tailyuanforest.jpeg" width="280" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Reconstruction of Permian Forest from Inner Mongolia (Jun Wang <i>et al</i>. 2012)</td></tr>
</tbody></table><br />
OK I'm back after a long hiatus due to extensive travel (yay) and work (boo) commitments. There have been a few things to cover over the next few weeks, but in the meantime, something a little, . . . umm . . . younger than we're used to here on Ediacaran - but there is a link.<br />
<br />
Working out how fossil organisms interacted is very difficult as they are usually found singularly or in small groups. Certain things, such as <a href="http://ediacaran.blogspot.com.au/2008/12/csi-cambrian.html">predation</a> for example, can be worked out using single of small groups of fossils, but community interactions require large scale preservation. Such ecological-scale preservation is rare, but some do exist, for example <a href="http://www.environment.gov.au/heritage/places/national/dinosaur-stampede/index.html">Cretaceous dinosaur footprints</a>, and <a href="http://www.canowindra.org/fishes.html">Devonian fish</a>. A new find from China has added to this small list.<br />
<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjI3kGp6jD-v6wMNQjtcES6sh1Ptxd6Um5TA2G0eBGXRuy22TMWTq8-ANbxWpjNLDT-M0Xy9rHUWBC3dt9ZM5MgwAsGM_C2uLV5QS6_BPBEn5H7FALTRnj2wQxT9kAfae-v_oZLOuwO11Pm/s1600/PermianchronTailyuan.jpeg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjI3kGp6jD-v6wMNQjtcES6sh1Ptxd6Um5TA2G0eBGXRuy22TMWTq8-ANbxWpjNLDT-M0Xy9rHUWBC3dt9ZM5MgwAsGM_C2uLV5QS6_BPBEn5H7FALTRnj2wQxT9kAfae-v_oZLOuwO11Pm/s320/PermianchronTailyuan.jpeg" width="248" /></a></div>In the earliest part of the Permian, around 298 million years ago, a large volcanic eruption in what is now northern China, resulted in a swampy region being covered by an approximately 100cm thick volcanic tuff. Just like in the more famous example of Pompeii, the tuff trapped and preserved everything beneath it. The ash fall buried and choked the plants, braking off twigs and leaves, felling trees, and preserved the forest remains in place.<br />
<br />
Now part of a coal field 8km west of Wuda, Inner Mongolia, the Taiyuan Formation has revealed a wealth of exceptional preservation, but also a wealth of ecological information. The site has allowed approx. 1000 square meters of Permian swamp to be uncovered and systematically investigated. It has allowed the reconstruction of Permian plants, and has also provided information on the relationships between the plants growing at the time.<br />
<br />
At the site, six groups of plants make up the vegetation, and an examination of the relationships shows several areas of distinctly different plant occurrences, as well as a number of patterns of co-occurrence. These allow for detailed reconstructions of the original forest, one of which is the photo at the start of this entry.<br />
<br />
Some of the exceptional preservation is shown below.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhEiaAQYi_lrHC8nrm0lhIHU3ia85sptdyJ6sgBOWKHa7_bZ8A6hgkTS0SAbRY-aQ3M3EOjAZ9gw9L6-mgTLiECF212K_TOyDr0-PdeSeUOrZ0wLXS9CwxlaCrH4tfshH6FCmoPDqUtcUaw/s1600/Tailyuanfossils.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhEiaAQYi_lrHC8nrm0lhIHU3ia85sptdyJ6sgBOWKHa7_bZ8A6hgkTS0SAbRY-aQ3M3EOjAZ9gw9L6-mgTLiECF212K_TOyDr0-PdeSeUOrZ0wLXS9CwxlaCrH4tfshH6FCmoPDqUtcUaw/s400/Tailyuanfossils.jpeg" width="296" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Sphenopsids and lycopsids fossils from the Taiyuan Formation: <i>(A) Asterophyllites longifolius</i>, and (B) associated <i>Paleostachya</i> type <i>strobili</i>; (C) <i>Sphenophyllum oblongifolius</i>, and (D) associated<br />
strobili; (E) <i>Sigillaria</i> cf. <i>ichthyolepis</i> leaf, (F) stem, (G) strobilus. (Scale bars, 2 cm in A, C, D, F, and G; 1 cm in B and E.)</td></tr>
</tbody></table><br />
So, what has this Permian deposit to do with the Ediacaran?<br />
<br />
Well, this ecologically-focussed investigation has also been undertaken for the Ediacaran fauna. There are a couple of examples of such eco-related investigations. <br />
<br />
The first is from the Ediacaran of Newfoundland. At Mistaken Point, the beds outcropping along the coast dip at shallow angles, which means that tennis court-sized areas of old sea floor are exposed along the cliff. Abundant Ediacaran fossils have been found on these surfaces . These fossils include spindle forms as well as the more familiar <i>Charnodiscus</i> disc-shaped forms. The relatively large expanse of uncovered old sea floor allows some interrelationships to be looked at.<br />
<br />
Interestingly (and in another link to the Permian find above), preservation here is different to that in South Australia. Here, fossils are found on the top surface of the bed. This is because the organisms and sea floor was covered by an ash falls from volcanic eruptions some time around 565 million years ago. As in the Permian example, ash covered everything and subsequently preserved a snapshot of life at the time.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhfH7Lvm35-UFsJKQp02KwXm36pMktUHEdcIqOks2DI7PI2gbxSgkj6HHaYVKsU_ciWKw7k45QU8CPb-3Zj8F1Lonf75hMjPcADEtsOaT6ohC7u6Ixg8TW5Sg31ib9b3S6WChl7VgkVo2BD/s1600/Mistakenpoint.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="142" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhfH7Lvm35-UFsJKQp02KwXm36pMktUHEdcIqOks2DI7PI2gbxSgkj6HHaYVKsU_ciWKw7k45QU8CPb-3Zj8F1Lonf75hMjPcADEtsOaT6ohC7u6Ixg8TW5Sg31ib9b3S6WChl7VgkVo2BD/s400/Mistakenpoint.jpeg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Ediacaran fossils from Mistaken Point, and the ash layer which has preserved them (<a href="http://geol.queensu.ca/museum/index.php?option=com_content&view=article&id=54&Itemid=61">photo credit</a>)</td></tr>
</tbody></table><br />
The second example comes from South Australia. In the Flinders Ranges, several Ediacaran locations occur in low-lying hills with gentle slopes. As the beds erode out of the soil, they move down slope. As the area is remote, there is little disturbance, and so it is possible to roam the slope picking up pieces of distinctive layers and reconstructing the Ediacaran sea floor.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj69uI3fsV4IaHH4WRhRW8BbHox4oe9PQrf61tU7LCDU-1g4oqitBXECSC_ltvl3M6znMf7C8QL1LVDmYOgJ5LgcWcV_QIHF775MbsmlbR4v_NKgaPA5xxkJXg3E4mqcEihUjyL1XrBQt9V/s1600/Ediacaraneco.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="157" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj69uI3fsV4IaHH4WRhRW8BbHox4oe9PQrf61tU7LCDU-1g4oqitBXECSC_ltvl3M6znMf7C8QL1LVDmYOgJ5LgcWcV_QIHF775MbsmlbR4v_NKgaPA5xxkJXg3E4mqcEihUjyL1XrBQt9V/s400/Ediacaraneco.jpeg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Reconstructing Ediacaran sea floors from South Australia, both in the field, and at the South Australian Museum (photo credit <a href="http://www.newsroom.vcr.edu/1796">1</a>, <a href="http://www.pandasthumb.org/archives/2006/stevesti.html">2)</a></td></tr>
</tbody></table><br />
The difference here is that the fossils are found on the underside of the bed, not on the top surface, which is normally contains ripple marks caused by current and wave action (as seen in the photo from the South Australian Museum above).<br />
<br />
The ability to look at whole communities, rather than individuals provides a much better understanding of what was going on in the past which makes sites where you can actually do that very important.<br />
<br />
<span style="font-size: x-small;"><br />
</span><br />
<span style="font-size: x-small;">Jun Wang, Hermann W. Pfefferkorn, Yi Zhangc, and Zhuo Feng. (2012) Permian vegetational Pompeii from Inner Mongolia and its implications for landscape paleoecology and paleobiogeography of Cathaysia. Proceedings of the National Academy of Science of the United States of America, Published online before print, <a href="http://www.pnas.org/content/early/2012/02/14/1115076109">doi: 10.1073/pnas.1115076109</a></span>Chris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.com5tag:blogger.com,1999:blog-5517176012861550589.post-75331201189495537652011-10-10T14:25:00.000+11:002011-10-10T14:25:39.918+11:00Palaeoporn 24<center><i><span style="font-size: large;">Tribrachidium heraldicum</span></i></center><br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgHuo7EhExwdjOFp50kgJWhMUb5zmp_LfMDP1dj7-prfVqXHfS1kgId2ENNZ20-zVHp_I_8mwZi6KSxjzpT52I1OGogMgyTjLt9kL4y0Nj8K7IHVudlakDvOTvxmdqGaSLS2Twki-fU4ZHL/s1600/Ediacaran+Tribrach1.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="260" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgHuo7EhExwdjOFp50kgJWhMUb5zmp_LfMDP1dj7-prfVqXHfS1kgId2ENNZ20-zVHp_I_8mwZi6KSxjzpT52I1OGogMgyTjLt9kL4y0Nj8K7IHVudlakDvOTvxmdqGaSLS2Twki-fU4ZHL/s400/Ediacaran+Tribrach1.jpg" width="248" /></a></div><br />
Ediacaran goes back to its roots with this Palaeoporn, with probably the most enigmatic of a group of enigmatics, <i>Tribrachidium heraldicum</i>.<br />
<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSBnvIAKp8X7sD6Kii0YaUNtaScXDEdmSwdIPsymYGJwHYOAmlHeWk2z7YV12JnqmMy2AjRVY08zr6zepa0pI-g3_5a7bwRuiWoJGqrHSwwoq-TL3C0cVIjk88cs0INETZBGt4FVYhPNDT/s1600/Ediacaran+TribrachJp.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="130" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSBnvIAKp8X7sD6Kii0YaUNtaScXDEdmSwdIPsymYGJwHYOAmlHeWk2z7YV12JnqmMy2AjRVY08zr6zepa0pI-g3_5a7bwRuiWoJGqrHSwwoq-TL3C0cVIjk88cs0INETZBGt4FVYhPNDT/s400/Ediacaran+TribrachJp.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i>Tribrachidium</i> (<a href="http://www.scc.u-tokai.ac.jp/sectu/sizensi/2002/ex_z0101.html">photo credit</a>)</td></tr>
</tbody></table><i>Tribrachidium</i> is a disc-shaped organism which is characterised by having three 'arms' which spiral out from the centre. <i>Tribrachidium</i> always occurs in negative hyporelief (pressing up into the bottom surface of the sandstone bed) indicating that it had a rigid body that pressed upwards into the overlying sand. The photo above is actually of a cast taken from a fossil so that the original body relief is shown - i.e. this is positive relief. The actual fossil is at right.<br />
<br />
The tripartite body plan of <i>Tribrachidium</i> is quite unusual as most metazoans are either bilaterally or radially symmetrical. <br />
<br />
So what is it? Well <i>Tribrachidium</i> is a cnidarian. Umm no, actually it's a lophophore (related to brachiopods), umm, or it could be an echinoderm, umm, no, it's an ecdysozoan (a group characterised by organisms that shed their external covering), no actually it's a sponge . . . possibly. Alternatively it could belong to a whole new phylum, the <a href="http://en.wikipedia.org/wiki/Trilobozoa">Phylum Trilobozoa</a>. Umm, maybe Class Trilobozoa, well, clade trilobozoa anyway.<br />
<br />
So its been a question of, "Look! Up in the sky! Is it a lophophore? Is it a cnidarian? No it's . . . , umm . . . , it's . . . , well . . . , it's a Trilobozoan! Yeah . . . , that's what it is, a Trilobozoan. <br />
<br />
[voice from the crowd] It's a what?<br />
<br />
Trilobozoan.<br />
<br />
[voice from the crowd] What's a Trilobozoan?<br />
<br />
Glad you asked.<br />
<br />
The Trilobozoa are predominately an Ediacaran group who's members have a tripartite or tri-radial body plan, typified by <i>Tribrachidium</i>.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiDrHmbLkVR2rfRH-O712u7Fz8paAYkjVv7Un4d50gqUArbcedB-qDulsRGVN3sEfTSbrO1RtBZOSzxOvfZpYr_T9QI0QONbnmQJGUDcnA9yQTt1aQ4RQwnOWTWf_KxmLKC-4q0wixPRpuH/s1600/Triblobozoa.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="285" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiDrHmbLkVR2rfRH-O712u7Fz8paAYkjVv7Un4d50gqUArbcedB-qDulsRGVN3sEfTSbrO1RtBZOSzxOvfZpYr_T9QI0QONbnmQJGUDcnA9yQTt1aQ4RQwnOWTWf_KxmLKC-4q0wixPRpuH/s400/Triblobozoa.jpeg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A triumvirate of Trilobozoa. <i>Albumares Brunsae</i> (x4) (left), <i>Anfesta stankovski</i> (x1) (top right) (<a href="http://downloads.palass.org/palaeobiology/16-30_section1.pdf">Photo credit</a>). <i>Rugoconites enigmaticus</i> (x1) (<a href="http://www.keyobs.be/fr/ebonino/html/ediacara.html">Photo credit</a>) </td></tr>
</tbody></table><br />
The group is a bit of a grab-bag with <i>Albumares</i> and <i>Anfesta</i> from Russia and maybe <i>Rugoconites</i>, as well as some others. The tripartite body plan is almost unique with modern examples confined to teratological (developmental defects) causes. Like <i>Tribrachidium</i>, other trilobozoans are usually found in negative hyporelief and, importantly, although not common, where they do occur in groups they do not overlap, indicating that they are not 'strandings' or simply groups of free swimming forms washed together (otherwise they would overlap).<br />
<br />
<i>Tribrachidium</i>, the most common and hence most studied, can also be found in size range of 3 to 30 mm indicating a growth pattern of organisms recruited to the sea floor and growing there, rather than a free swimming form where the sizes would be similar due to current activity. Trilobozans are thought, then, to have been sessile filter feeders, attached to the microbial mats, normally by a bulb-like structure, throughout adult life.<br />
<br />
It appears as though the tripartite body plan, or derivatives of it, were quite common in the Ediacaran. Finds such as <i>Ventogyrus</i> are being reinterpreted as a stalked trilobozoan, but placed within the Phylum Cnidaria. Another form, <i>Eoandromeda octobrachiata</i>, though to be related to comb jellyfish (a group of vicious killer jellyfish), is also though to share a number of features in common with <i>Tribrachidium</i>.<br />
<br />
So evidence is growing that trilobozoans may well be Cnidarian.<br />
<br />
Vicious killer jellyfish, trilobed body plans! The Cnidaria have a lot to answer for!<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHPkOr0GLkRCSBS1vxdSvuAd8RrCfXH-2gjjjpEpNNNVVvMpN8eTMioHP77UKwHDG24g-cVZqF8TvI3d7qVcRWLHuxC0md4cnYTNMCiKQjSb5wyAwU0RfTupBcZyeEFCY2cIVWAgZ84EJQ/s1600/Trilobozoans.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="183" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHPkOr0GLkRCSBS1vxdSvuAd8RrCfXH-2gjjjpEpNNNVVvMpN8eTMioHP77UKwHDG24g-cVZqF8TvI3d7qVcRWLHuxC0md4cnYTNMCiKQjSb5wyAwU0RfTupBcZyeEFCY2cIVWAgZ84EJQ/s400/Trilobozoans.jpeg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Trilobozoan Cnidarians? Reconstructed. <i>Tribrachidium</i> stamp (left). <i>Ventogyrus</i> (<a href="http://commons.wikimedia.org/wiki/File:Ventogyrus_chistyakovi_recon.jpg">photo credit</a>)</td></tr>
</tbody></table>Chris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.com6tag:blogger.com,1999:blog-5517176012861550589.post-18329029299491989742011-08-28T21:09:00.000+10:002011-08-28T21:09:42.777+10:003.4 Billion Year Old Microfossils? . . . Umm Yes (Probably)<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivBXcY5HWVtilNH5uUViu4oqs_5FpT2ZIBqkXtfaHqrnYPIMV2WExy1hNSAfBb-bwo6ulC_Cm55zkSIiRnv38K6CFL9BxGyJXWsN2fPspPeu8gj-J932HDY0jCCheU5_8l6IYHTJOlIv6W/s1600/3.4BaheaderUWA.jpeg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="160" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivBXcY5HWVtilNH5uUViu4oqs_5FpT2ZIBqkXtfaHqrnYPIMV2WExy1hNSAfBb-bwo6ulC_Cm55zkSIiRnv38K6CFL9BxGyJXWsN2fPspPeu8gj-J932HDY0jCCheU5_8l6IYHTJOlIv6W/s640/3.4BaheaderUWA.jpeg" width="640" /></a></div><div style="text-align: center;"><span style="font-size: x-small;">S</span><span style="font-size: x-small;">shhh, be vewy vewy quiet. We’re hunting Awchean pwokawyotes.</span></div><br />
There is good carbon and sulphur isotope geochemical evidence that life has existed on Earth from the early Archean. This life is thought to consist of small prokaryote cells with a penchant for sulphur instead of oxygen. <br />
<br />
However, identifying actual fossil evidence is very tricky for a number of reasons. One of the major ones being, that given the 3.5 billion year time span and plate tectonics, few rocks from this period of Earth history remain on the surface. Of those that do, most either were unsuitable to preserve life in the first place (e.g. volcanic rocks) or have been metamorphosed until any possible organic trace has been cooked to oblivion. <br />
<br />
So, if you want to go hunting Archean microbes you need to look in an area with rocks that have been relatively unmolested for some 3.5 billion years or so.<br />
<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhN5AY-WLFfKpU7aumcjUuOFp4wPYqMyG6Y3X8iBme4eA2wrjw-3zy-TCRDx6uu0_M4yq9whtf7LHNLyaGoU8fCIubsDqZHxJGiZHF5vKMgqBkmzvPZsujWt6OelU67Fu8JO5PuvXVNgte/s1600/3.4Bachronology.jpeg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhN5AY-WLFfKpU7aumcjUuOFp4wPYqMyG6Y3X8iBme4eA2wrjw-3zy-TCRDx6uu0_M4yq9whtf7LHNLyaGoU8fCIubsDqZHxJGiZHF5vKMgqBkmzvPZsujWt6OelU67Fu8JO5PuvXVNgte/s320/3.4Bachronology.jpeg" width="179" /></a></div>Presenting the <a href="http://en.wikipedia.org/wiki/Pilbara_craton">Pilbura Craton</a>, Western Australia. The Craton consists of (relatively) unaltered 3.7-2.6 billion year old rocks formed of a granite–greenstone terrane consisting of a series of dome shaped granitoid bodies, overlain by an extensive sequence of Archaean and later metasediments. Within the Craton, the East Pilbara Terrane contains a suite of approx. 3.4 billion year old sedimentary rocks which occur sandwiched between two suites of volcanic rocks.<br />
<br />
This is the Strelley Pool Formation and is thought to be between 3426-3340 million years old. At the base of Formation, sitting unconformably on underlying 3515 million year old basalts, is a remarkably well preserved sandstone. (The ridge in the header image above. The red dots mark the position of the unconformity between the underlying basalts and the Strelley Pool Formation. Image (sans Elmer) from Wacey <i>et al.</i> 2011. Supplementary Information)<br />
<br />
The sandstone is dark coloured at the base, due to it being carbonaceous- and pyrite-rich, where it sometimes fills channels eroded into the underlying basalt. Above this, the sandstone becomes lighter as the carbonaceous matter and pyrite disappear, before passing into overlying limestones - which contain possible stromatolites - and cherts. <br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiNcmy_ybqE190DckUpOxrv6xgMpfBqpqgj80hPFRq8DJ92p7Zss3nNLwe3ul7LF-dINkqgjAu5kQ4u40U5MFSshWIksDfSvsBIFPGoXisowL_I-F6R1lXG7sV6vAmtj4b-8uCbNjCvC4mH/s1600/3.4Bagrains.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiNcmy_ybqE190DckUpOxrv6xgMpfBqpqgj80hPFRq8DJ92p7Zss3nNLwe3ul7LF-dINkqgjAu5kQ4u40U5MFSshWIksDfSvsBIFPGoXisowL_I-F6R1lXG7sV6vAmtj4b-8uCbNjCvC4mH/s320/3.4Bagrains.jpeg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Thin section photomicrograph showing multiple generations of carbonaceous material and silica cements within the Strelley Pool sandstone. <b>DQ</b>, detrital quartz grains. <b>C1</b>, carbon material, interpreted as a biolfilm, covering quartz grains. <b>S1</b>, first silica cement layer, up to c. 30 μm partially filling the void space between the detrital quartz grains. <b>C2</b>, A second carbon biofilm covering the surface of the S1 silica layer. <b>S2</b>, a second generation of silica cement precipitated in the larger pore spaces. <b>C3</b>, a third generation of carbon biofilm. (Wacey <i>et al.</i> 2011. Supplementary Information).</td></tr>
</tbody></table>This fantastic thin section photomicrograph provides a wealth of information that allows us to reconstruct how the sandstone was formed. The grains are well rounded detrital quartz. Grains of detrital pyrite are also present. The grains are covered with a thin film of carbonaceous matter, and show a number of silica cementation events, some of which show a dripstone texture.<br />
<br />
A second film of carbonaceous matter covers the primary silica cement layers. The central spaces between grains not occupied by the silica layers and carbon films, is filled with chert. <br />
<br />
From this we can say that the well-rounded, large quatrz and pyrite grains suggest the sandstone was deposited in a high energy environment, such as a beach or estuary. The sandstone is also very clean - there is no fine material such as silt or clay - also supporting a high energy environment of deposition which would have washed out all the fine-grained material such as silt and clay.<br />
<br />
The several episodes of silica cementation suggests cyclic inundation of silica-rich fluids into porous, clean sands. <br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhINzV84htflTG4eRTOEfShkSCZ2HxEr_xdpb8_p2RPyAlFic5JserJUnywS8Vph34D77VZY20jKS0rG5pYIJfCUg1Me0S85TynQFTy6BdUlYiZznbkyfEJF1UkJuwav1p1xuc1cxMU_pjJ/s1600/3.4Badripstones.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="129" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhINzV84htflTG4eRTOEfShkSCZ2HxEr_xdpb8_p2RPyAlFic5JserJUnywS8Vph34D77VZY20jKS0rG5pYIJfCUg1Me0S85TynQFTy6BdUlYiZznbkyfEJF1UkJuwav1p1xuc1cxMU_pjJ/s320/3.4Badripstones.jpeg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Thin section showing <b>b</b>, Rounded quartz grain separated from a carbon-rich chert infilling by a dripstone cement (white arrow). <b>c</b>, Rounded grain of detrital pyrite (black grain) with a dripstone chert cement and carbon coating (red arrow). (Wacey <i>et al.</i> 2011).</td></tr>
</tbody></table>The dripstone cements are exactly that, they appear as 'drips' of cement on the bottom on grains. This is because they form when the grains are exposed to air and trapped fluid flows to the bottom of the grains. This supports a beach-type environment which was influenced by <a href="http://en.wikipedia.org/wiki/Vadose_zone">valdose</a> conditions - where non-marine groundwater is retained by adhesion to grains or by capillary action. <br />
<br />
The evidence suggests then, that the sandstone was deposited in a nearshore beach-type environment which helped smooth out the quatrz and pyrite grains, and removed any fine material. During this time the first layer of carbonaceous material was formed around the grains (<b>C1</b> above). Periodically, the highly porous sand came under the influence of valdose conditions, allowing the precipitation of silica cement around the grains (<b>S1</b> above), trapping the carbonaceous layer, but maintaining the porous nature of the sand. Subsequently a second layer of carbonaceous material <b>(C2</b> above) was formed over the <b>S1</b> cement, possibly suggestive of a reversion to marine influences. A second round of valdose conditions produced a second cementation layer (<b>S2</b> above). Followed by another return to marine influences and a third carbonaceous layer <b>(C3</b> above). Finally, after the sands were buried, subsequent chert deposition provided the source for the last event, the filling of the remaining pore space with chert.<br />
<br />
Before we look at the carbonaceous material in more detail there is the question of the link between the detrital pyrite grains and the carbonaceous matter.<br />
<br />
The detrital pyrite grains are large, much larger than the possible cells in the carbonaceous matter, and are rounded. This suggests that the pyrite is not a product of possible organic activity. There is some pyrite within the carbonaceous matter, but this pyrite is much smaller and angular in shape - as expected if they have been precipitated as a result of organic activity. The detrital pyrite grains are also covered by the silica cement layers. The evidence suggests that the pyrite is primary - that is it was present as an original constituent of the sand - rather then being a product of organic activity. As the pyrite only occurs in the base of the sandstone, primarily in erosive channels in the underlying volcanics, it seems likely that the pyrite grains were formed from the erosion of underlying rocks and have been left behind as a lag deposit as pyrite grains are much heavier that similar sized grains formed from other materials like quartz. The renewed influx of sediment resulted in the pyrite grains mixing with the quartz grains to form a pyrite-rich basal sand. Subsequent deposts of sand did not have the pyrite grains and so were deposited free of pyrite and carbonaceous matter. Remember also that the 3.4 Bya atmosphere has precious little in the way of free oxygen, so the pyrite would be quite stable under surface conditions.<br />
<br />
Since the detrital pyrite and carbonaceous matter are absent from the sandstone above the basal layer, there does appear to be a connection between the detrital pyrite and the carbonaceous matter. It appears that the carbonaceous matter is present because of the pyrite.<br />
<br />
To answer why the carbonaceous matter should be linked to the pyrite, we first need to know what the carbonaceous matter is and what it contains.<br />
<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhkfcuNTjtDbH3DOzRSZO26VWtoO6JS8yx5SBXCBomyqBl4SyodbeciQXJbCkZwKPEGUlxC_GqYoUx32ODJgqENYRU2bZwuFMr8eu8XoVJHrDeJfW0Y_jQjCT0HumJL6oJsAOtN-Nukhkaw/s1600/3.4Ba10um.jpeg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="165" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhkfcuNTjtDbH3DOzRSZO26VWtoO6JS8yx5SBXCBomyqBl4SyodbeciQXJbCkZwKPEGUlxC_GqYoUx32ODJgqENYRU2bZwuFMr8eu8XoVJHrDeJfW0Y_jQjCT0HumJL6oJsAOtN-Nukhkaw/s320/3.4Ba10um.jpeg" width="197" /></a></td></tr>
</tbody></table>Wacey <i>et al.</i> have found a number of elements (at right) in the carbonaceous film that look like prokaryote cells (or at least what prokaryote cells would look like after 3.4 billion years). So the question is, are we dealing with 3.4 billion year old microfossils? <br />
<br />
<a href="http://en.wikipedia.org/wiki/Raman_spectroscopy">Ramen</a> spectroscopy (it's to do with lasers and nothing to do with <a href="http://en.wikipedia.org/wiki/Rendezvous_with_Rama">Arthur C. Clarke</a>) supports a disordered structure. This is important because organic matter is disordered, inorganic carbonaceous matter is ordered - abiotic graphite, for example, is found in rocks of this age but shows a well ordered internal structure. So that's a tick for organic. Also, an analysis of the structures indicates the presence of carbon, nitrogen and sulphur in the possible cell wall structures. Again a tick for organic as these are essential for organically formed structures, but not for inorganic ones.. Finally analysis of the carbon in the possible cell walls shows a 26-39 parts per thousand enrichment in <sup>12</sup>C compared with atmospheric CO2. This also support the structures being organic as only organic activity can partition light <sup>12</sup>C from the 'heavier' <sup>13</sup>C to such an extent.<br />
<br />
So the evidence suggests that the structures are organic, but are they microfossils?<br />
<br />
Well, the shapes are round and tube-shaped. So, as prokaryotes tend to be round and tube-shaped, this is a good thing. However, a number of inorganic processes can produce round and tube shapes. So, by itself, this doesn’t tell us much. The specimens do show some evidence of folding, which organic shapes would do that inorganically produced shapes wouldn’t. So shape is a point in favour of them being microfossils, but not conclusive.<br />
<br />
Size is an interesting one. Prokaryotes come in a range of sizes, but modern forms are generally around the 10 μm mark. The forms found range in size from 5-25 μm, with an average size of around 10 μm, not a bad comparison with modern forms. <br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhItEGIfLN873OPwAiX-XJhHClWEya8f_PY1EZLj_MI1AhefddPShOaKTTaAY8vksuZmyxmsdh95eGZJiDAh_K0LAh2cyTFl9lzpFlUgWVMtKq49LOctaZbfWiGD0RjT3IqVi1cCrJs18OJ/s1600/2.4Basizedistrobution1.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="222" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhItEGIfLN873OPwAiX-XJhHClWEya8f_PY1EZLj_MI1AhefddPShOaKTTaAY8vksuZmyxmsdh95eGZJiDAh_K0LAh2cyTFl9lzpFlUgWVMtKq49LOctaZbfWiGD0RjT3IqVi1cCrJs18OJ/s400/2.4Basizedistrobution1.jpeg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Size distributions of microfossils from the Strelley Pool Sandstone compared to those from three younger biological microfossil assemblages and one abiotic spherulite assemblage. (Wacey <i>et al.</i> 2011).</td></tr>
</tbody></table>Also the distribution of sizes is similar to that of other accepted fossil forms in the 1.9 billion year old Gunflint Chert of Ontario and the 0.8 billion year old Bitter Springs formation of Central Australia. These latter fossils are considered to be Prokaryote fossils. However, this does not represent the total distribution.<br />
<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjzSIsuQBfwsdVVXiPzKmDQeKYlUT666TQgYe31ojK5rEwBdMecK8tAwpbe2krGrrPccy0lgiSqaj07mw-GWeAMhT_Atzex3MGR6AXEjE8rhj97p2Y7aWkF6dyYiFgy-Ah8OXUyWe3Yziml/s1600/3.4Ba80um.jpeg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjzSIsuQBfwsdVVXiPzKmDQeKYlUT666TQgYe31ojK5rEwBdMecK8tAwpbe2krGrrPccy0lgiSqaj07mw-GWeAMhT_Atzex3MGR6AXEjE8rhj97p2Y7aWkF6dyYiFgy-Ah8OXUyWe3Yziml/s200/3.4Ba80um.jpeg" width="190" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">80 μm giant from Wacey <i>et al.</i> 2011</td></tr>
</tbody></table>As Wacey <i>et al.</i> state, and <a href="http://scienceblogs.com/pharyngula/2011/08/a_questions_about_those_ancien.php">PZ has discussed</a>, there are larger specimens, if rare, up to 80 μm in size (see left), which is much larger that normal. However, prokaryotes do exhibit larger size ranges, so it is not implausible that cells could range up to this size. <br />
<br />
Another explanation could be that these large ‘cells’ represent a cluster of cells in which only the outer cell walls in contact with pore fluids have been preserved, while the internal walls dividing individual cells are not preserved. Certainly the structures arrowd in the large specimen could represent the boundaries between cells as much as they could represent folding. The presence of silica micro-crystals in cell walls does suggest that silica-rich pore fluids played a part in the preservation process. So the larger specimens could be the remains of clumps of cells, or possibly a different group of organisms from the smaller ones.<br />
<br />
The numerous lines of evidence tends to support the identification of these structures as organic ans potentially prokaryote cells, making them the oldest life forms so far identified. <br />
<br />
So why the attraction to sulphur? Well, in the absence of oxygen, SO<sub>4</sub><sup>2-</sup> makes a good terminal electron acceptor. <a href="http://sandwalk.blogspot.com/2011/08/oldest-cells.html">Larry Moran</a> has the details.<br />
<br />
Given the age, it will probably be impossible to get absolute evidence that any particular set of structures represent Archaen prokaryotes, but the evidence Wacey <i>et al.</i> 2011 present is probably as close as we could reasonably expect to come.<br />
<br />
So with these Archaen prokaryotes, and the Ediacaran fauna, when it comes to Precambrian life, AUSTRALIA ROCKS!<br />
<br />
<span style="font-size: x-small;">Wacey, D., Kilburn1, M.R., Saunders, M., Cliff, J. and Brasier, M.D (2011) Microfossils of sulphur-metabolizing cells in 3.4-billion-year-old rocks of Western Australia. Nature Geoscience. Published online Aug. 21. <a href="http://www.nature.com/doifinder/10.1038/ngeo1238">DOI: 10.1038/NGEO1238</a></span>Chris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.com8tag:blogger.com,1999:blog-5517176012861550589.post-13199517237277094842011-08-13T17:04:00.000+10:002011-08-13T17:04:41.894+10:00Palaeoporn 23<div style="text-align: center;"><span style="font-size: large;">Indiana Nedin and the Temple of Kaili</span></div><div class="separator" style="clear: both; text-align: center;"></div><br />
<center><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi0S71jvUjb08m3CAxn0vroWWUJ_tgrMcDtWLgcdmm5YUYJ_BRD9rqKuqcgX_8ZRh13SBTMHpSG03koksEiqlh7U8HEcmWyr58HxiiMI1mZFJEFu_a5v4QP55Wgupe9y9Qwlo-JdorySmsb/s1600/ChinaKailime.jpeg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="335" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi0S71jvUjb08m3CAxn0vroWWUJ_tgrMcDtWLgcdmm5YUYJ_BRD9rqKuqcgX_8ZRh13SBTMHpSG03koksEiqlh7U8HEcmWyr58HxiiMI1mZFJEFu_a5v4QP55Wgupe9y9Qwlo-JdorySmsb/s400/ChinaKailime.jpeg" width="400" /></a></center><br />
OK, I'm back, after several months of work and travel, which included losing the top of the <a href="http://ediacaran.blogspot.com/2011/02/paris-feb-2011.html">Eiffel Tower</a>, and <a href="http://ediacaran.blogspot.com/2011/07/paris-june-2011.html">finding</a> it again, avoiding an <strike>Ebola</strike> E-coli outbreak in Hamburg, and retracing the route of <i>The Italian Job</i> in Torino, it's about time I got back to some real work and started posting on the blog again!<br />
<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhQtuBhFyr5b6Ikj4lZ5_hPc1vx1L5hns4HM8R9PBnHTYtyVbYfUxc4IJQWKfwLMExUMBKo03wH2JtTkMQYvKYZdGR_kep93spWJ8uvGHl2FYrkZjYQHrUUePS7-xV3AZXnnfybfP4Ks0TX/s1600/Cambrianchron1Kaili.jpeg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhQtuBhFyr5b6Ikj4lZ5_hPc1vx1L5hns4HM8R9PBnHTYtyVbYfUxc4IJQWKfwLMExUMBKo03wH2JtTkMQYvKYZdGR_kep93spWJ8uvGHl2FYrkZjYQHrUUePS7-xV3AZXnnfybfP4Ks0TX/s320/Cambrianchron1Kaili.jpeg" width="183" /></a></div>Continuing the tradition of <a href="http://ediacaran.blogspot.com/2008/11/palaeoporn_09.html">famous</a> <a href="http://ediacaran.blogspot.com/2008/12/palaeoporn.html">fossil</a> <a href="http://ediacaran.blogspot.com/2010/10/palaeoporn-19.html">sites</a> wot I have visited, the photo above (taken a few years ago now) is of me doing my Indiana Jones impression on a hilltop at the site of the Kaili Formation in Guizhou province, southwest China, some 550 kilometres ENE of Kunming and the Changjiang fauna. <br />
<br />
The Kaili formation is basal Middle Cambrian in age (see figure at right) and contains the Kaili Biota, a Changjiang/Burgess Shale type lagerstätte. Given it's age, the biota sits midway in age between the Lower Cambrian Changjiang fauna and the Middle Cambrian Burgess Shale fauna. <br />
<br />
As would be expected, the Kaili biota shows significant overlap with both the Chengjiang and Burgess faunas in terms on genera in common. <a href="http://en.wikipedia.org/wiki/Kaili_Formation">Wikipedia</a>, suggests that of the (quite diverse) 110 genera occurring in the Kaili biota, 30 are shared with the Chengjiang fauna, and 40 are shared with the Burgess fauna.<br />
<br />
The Kaili biota is thought to represent an outer-shelf environment and contains large numbers of planktonic trilobites, and eocrinoids, along with a range of soft bodied forms such as neroiids, <i>Wiwaxia</i> and <i>Marrella</i><br />
<br />
However, that's not what I want to talk about. See the village to my right in the photo above (click on the photo to enlarge)? That was our way down from the site. That's what I want to talk about because when we entered the village we were greeted with this:<br />
<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4CzxmC8lX-CQ1VfYG_fwl433x4DvI53Dmayaxpeo7s6NNCP4fDZMw6bX_ND9aNWOJ6-a7oWpsx18-GWWF9aighdINjZsHz2sxrHlqALgRPP23txxGY9drUXXZyAHhnXxTObstoAQcXoUM/s1600/China+Geuzhou+village+food.jpg" imageanchor="1" style="margin-left:1em; margin-right:1em"><img border="0" height="400" width="252" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4CzxmC8lX-CQ1VfYG_fwl433x4DvI53Dmayaxpeo7s6NNCP4fDZMw6bX_ND9aNWOJ6-a7oWpsx18-GWWF9aighdINjZsHz2sxrHlqALgRPP23txxGY9drUXXZyAHhnXxTObstoAQcXoUM/s400/China+Geuzhou+village+food.jpg" /></a></div><br />
We had entered a village of the Mountain Miao Minority Peoples of Guizhou, and they laid on a traditional welcome ceremony for us. This started with two local girls in full traditional costume offering food and drink to each person as they entered. The traditional dress included amazing jewelry in solid silver! On this occasion we were offered fish and some lethal alcoholic local brew from a ceremonial horn.<br />
<br />
Once inside we were treated to a series of traditional dances, again performed by the girls of the village complete with elaborate gorgeous silver jewelry.<br />
<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjX6s6ArFjs-cz5pquC0LIxWJZn4Mb9Z7TmVt91aDtlp7ayjO4qJ7aVvA2qssb0d7_MlOcZcmJQ6jmo5jJQwipbTEAmlVxxhWYoZ230EYm3W_Yz1tqSN7tRywj3YJz-dRyiwLAN8LXZ1nK3/s1600/China+Geuzhou+village+dance.jpg" imageanchor="1" style="margin-left:1em; margin-right:1em"><img border="0" height="260" width="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjX6s6ArFjs-cz5pquC0LIxWJZn4Mb9Z7TmVt91aDtlp7ayjO4qJ7aVvA2qssb0d7_MlOcZcmJQ6jmo5jJQwipbTEAmlVxxhWYoZ230EYm3W_Yz1tqSN7tRywj3YJz-dRyiwLAN8LXZ1nK3/s400/China+Geuzhou+village+dance.jpg" /></a></div><br />
We were not informed that this was going to happen so it was a complete surprise. It was an amazing experience, and was the perfect end to the day.<br />
<br />
<br />
Further Reading<br />
<br />
ZHAO Yuanlong, ZHU Maoyan, Loren E. BABCOCK, YUAN Jinliang, Ronald L. PARSLEY, PENG Jin1, YANG Xinglian1, WANG Yue1 (2005) Kaili Biota: A Taphonomic Window on Diversification of Metazoans from the Basal Middle Cambrian: Guizhou, China. Acta Geologica Sinica; 79(6) 751–765. <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1755-6724.2005.tb00928.x/abstract">DOI: 10.1111/j.1755-6724.2005.tb00928.x</a><br />
<br />
Chris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.com10tag:blogger.com,1999:blog-5517176012861550589.post-51994753681438751072011-07-16T14:54:00.000+10:002011-07-16T14:54:35.431+10:00Paris June 2011<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhzNxM08rKu_90vatp9sqLwBt1DNLGbueDfVhTEJMMiswbwNU12rXCilvOtP4Qa32Xsgt2AsTnZiHO2E3ccjBAGH2h0uTQVf_8w2dSoHg6tYAXQW8ShhlAgX4psgsnL6vi7T6NxHxvMCZs5/s1600/Effel1.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhzNxM08rKu_90vatp9sqLwBt1DNLGbueDfVhTEJMMiswbwNU12rXCilvOtP4Qa32Xsgt2AsTnZiHO2E3ccjBAGH2h0uTQVf_8w2dSoHg6tYAXQW8ShhlAgX4psgsnL6vi7T6NxHxvMCZs5/s400/Effel1.jpg" width="400" /></a></div><br />
Good news. The bit of the Eiffel Tower that was <a href="http://ediacaran.blogspot.com/2011/02/paris-feb-2011.html">missing in February</a> is now back.Chris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.com0tag:blogger.com,1999:blog-5517176012861550589.post-14106987362100725202011-05-20T21:34:00.000+10:002011-05-20T21:34:59.375+10:00HamburgThings have been a bit quiet recently because inexplicably, the people who pay me actually want me to do stuff!<br />
<br />
Part of that stuff will have me at a loose end in Hamburg on the weekend of 11th and 12th June. So if anyone has any suggestions about things to do in Hamburg, I'd be grateful for some tips.<br />
<br />
Meanwhile, normal service will be resumed as soon as possibleChris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.com3tag:blogger.com,1999:blog-5517176012861550589.post-14461635975435445202011-04-03T15:36:00.000+10:002011-04-03T15:36:10.339+10:00Mopping up some Ediacaran Enigmatics<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEglaw-coOlIDMcYJ4_JHtOB8tpmYlL91ehncBeN2Bxko2GlJZUR3uWeqtDuygqB-tc6zN_BCLExDDf6r0dq7CikJ1JH9CMxHGAjzHtupQE5PB3ZaXdkYxqPmDf48h-2RV5KBweApm0rbZOo/s1600/Mophead.jpg" imageanchor="1" style="margin-bottom: 1em; margin-left: 1em;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEglaw-coOlIDMcYJ4_JHtOB8tpmYlL91ehncBeN2Bxko2GlJZUR3uWeqtDuygqB-tc6zN_BCLExDDf6r0dq7CikJ1JH9CMxHGAjzHtupQE5PB3ZaXdkYxqPmDf48h-2RV5KBweApm0rbZOo/s320/Mophead.jpg" width="200" /></a></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEht2yL-Fs64FGXBwEn_bf8PUjNfgTwaF3cQrV0CaxrKQKeDyl1pxPJMCVQk4jfDMFfUc40_SI8DMiyAgwxRvKJTFm4Q-7r8LhDByWIPmftLDod6deCH6X57_zOImwMHwSWpGp6EgSujgFKf/s1600/Mop6.jpeg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><br />
</a></div>The most common form of preservation of Ediacaran fossils in the Flinders Ranges of South Australia is by sands covering objects on the sea floor and masking them. Much of the sea floor was covered with algal and bacterial mats, or films, that add an extra dimension to the structures preserved by the covering sands. We have to take this extra dimension into account if we are to successfully interpret what it is that has been preserved. Some organisms lived on the mats, some below, and some had elements below and elements above. Understanding the interactions between organism, mat and sand will allow us to better understand what was going on at the time and help separate out body fossils from trace fossils from non-biogenic traces.<br />
<br />
A good example of this are "mops".<br />
<br />
"Mops" are a series of abundant, distinct structures which look like the head of a mop - hence the name. "Mops" are always preserved in <a href="http://ediacaran.blogspot.com/2011/01/770ma-ediacara-fossils-from-kazakhstan.html">hyporelief</a>, that is on the underside of the rock, unusually though, they can be either positive - standing up from the surface like a pimple, or negative - a depression in the surface like a dimple. Most Ediacaran fossils are usually either one or the other.<br />
<br />
Tarhen <i>et al.</i> studied a series of "mops" which show a highly varied shape and structure, but found some consistent features.<br />
<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiy8HTdj4ix9RhOUoMxhlFurT6Bl4ju3WRCHOeEujafouwmNJJQKto4gAKQxp7MK7VToRgf5Fke1ZoCLjuhEbrrAvQTzLhJEIfPEqGHWRC1z0LihfGh0ICjaUbG_U8dQfIxOI23queFqzG5/s1600/Mop1.jpeg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="137" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiy8HTdj4ix9RhOUoMxhlFurT6Bl4ju3WRCHOeEujafouwmNJJQKto4gAKQxp7MK7VToRgf5Fke1ZoCLjuhEbrrAvQTzLhJEIfPEqGHWRC1z0LihfGh0ICjaUbG_U8dQfIxOI23queFqzG5/s400/Mop1.jpeg" width="480" /></a></div><div style="text-align: justify;"><span style="font-size: x-small;"><center>Mop structures in hyporelief from the Ediacaran of South Australia. <br />
Scale bar = 2cm. (Tarhan <i>et al.</i> 2010)</center></span></div><br />
(1) "Mops" are always orientated within 10 degrees of the palaeocurrent as derived from a number lines of evidence. <br />
<br />
(2) They have a distinct margin at one end - considered to be the distal or far end. This can be straight (arrowed in (A) above), curved (in (B)) or lumpy (in (C)).<br />
<br />
(3) They have a series of roughly parallel lines running at around 90 degrees to the margin (arrowed in (B) above). These appear filament-like and can be either linear or wavy and tangled<br />
<br />
These features can vary even within the same bed and between specimens in close proximity.<br />
<br />
They do tend to appear in close association with the disc form <i>Aspidella</i>, which it though to represent the holdfast of a <i>Charniodiscus</i>-like organism or sea pen. But are they fossils or non-biogenic marks?<br />
<br />
Well they appear biogenic. The association with <i>Aspidella</i> is too strong to be random. But are they body or trace fossil? Well, they are a little of both.<br />
<br />
The association with <i>Aspidella</i> appears important. <i>Aspidella</i> is the holdfast of a sea pen-like organism, which had a large bulbous holdfast buried in the sediment, with a stalk and frond rising up into the water column. So the organism has some elements (the holdfast) below the bacterial mat, and some (the frond) above the mat.<br />
<br />
In this configuration, the frond will be subject to water currents. What is though to have happened is that strong currents carrying the sand that will eventually overlay the organisms has hit the frond and basically dragged the whole organism including the holdfast, in the direction of the palaeocurrent. As the holdfast is under the mats, this dragging has uprooted the holdfast and dragged it through the microbially bound mat layer. The parallel lines represent torn-up bits of mat which were attached to the top of the holdfast. Lumpy margins of the 'mops' are probably caused by small lumps of sediment trapped next to the holdfast.<br />
<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiXeBf2eWRGMZ-8Tk8Jl0EM-3UCPnDG1wtF_FOw3XyEWeu3lPi3ds5T5u-emyHZjUTrL_LuPjo1Xa4YVgnBmUXbpEX1w5tqdzK8Z1RCpIPn_tO4uuWBcWlsuAg0EKXlSjE1LweMvHrN84ND/s1600/Mop4.jpeg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="277" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiXeBf2eWRGMZ-8Tk8Jl0EM-3UCPnDG1wtF_FOw3XyEWeu3lPi3ds5T5u-emyHZjUTrL_LuPjo1Xa4YVgnBmUXbpEX1w5tqdzK8Z1RCpIPn_tO4uuWBcWlsuAg0EKXlSjE1LweMvHrN84ND/s400/Mop4.jpeg" width="400" /></a></div><div style="text-align: justify;"><span style="font-size: x-small;"><center>Formation of "mops". A: Normal conditions. B: Current drag. C: Current induced structures. <br />
D: Sand deposition. E: Preservation. (Tarhan <i>et al.</i> 2010)</center></span></div><br />
This explanation can explain a number of structures seen in Ediacaran rocks. One in particular is <i>Pseudorhizostomites</i>.<br />
<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-ZvyBwlxsEB1duaup0o_bMU9xmMOtmKY4FkL9M6wM8JxaHEi11y_ay1_BsztCVL1i2SxPw7HZnUkS7jeabthPcEXDlf7sAyQBu5A0UrKSxecxycDjl0vRXCE4UhkFfVFY8XofTN3m-AD0/s1600/Mop7Ps.jpeg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="158" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-ZvyBwlxsEB1duaup0o_bMU9xmMOtmKY4FkL9M6wM8JxaHEi11y_ay1_BsztCVL1i2SxPw7HZnUkS7jeabthPcEXDlf7sAyQBu5A0UrKSxecxycDjl0vRXCE4UhkFfVFY8XofTN3m-AD0/s320/Mop7Ps.jpeg" width="320" /></a></div><div style="text-align: justify;"><span style="font-size: x-small;"><center><i>Pseudorhizostomites</i>. Scale bar = 2 cm. (Tarhan <i>et al.</i> 2010).</center></span></div><br />
<i>Pseudorhizostomites</i> has been interpreted as a <a href="http://en.wikipedia.org/wiki/Rhizostomae">rhizostomean</a> medusa (a jellyfish without tentacles), and even a gas escape structure formed during the decay of an organism. But an interesting interpretation based on the 'mop' formation, is that they are <i>Aspidella</i>-like holdfasts that have been torn free by current action, but vertically rather than in a more horizontal direction. So they have been plucked out of the sediment rather than being dragged along.<br />
<br />
Another structure that appears related is one associated with actual holdfasts.<br />
<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgCamIQyNpfinGk3463RiG3e9necY767gnghY-DpLU7w9rXCY22G7QvsQsTeyG4-rP7wG2tkN41jJuAHpXMZhO4WJKM1KcC6ejXWPmUQBMHQB_H5jGJ9JBn3sLUZR-iO9ZQfNGTYRZ5asT3/s1600/Mop8.jpeg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="290" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgCamIQyNpfinGk3463RiG3e9necY767gnghY-DpLU7w9rXCY22G7QvsQsTeyG4-rP7wG2tkN41jJuAHpXMZhO4WJKM1KcC6ejXWPmUQBMHQB_H5jGJ9JBn3sLUZR-iO9ZQfNGTYRZ5asT3/s320/Mop8.jpeg" width="320" /></a></div><br />
Here the holdfast has remained intact and in place, but the stem has been flattened and the surface of the holdfast has been distorted by the sheer forces caused by the current pushing the frond and stem over.<br />
<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhLGwgqNdE-QdAVtL61wkkdmOFv2eDDQazmnMlEq959sZND0shUaDDbIRPJEnb8xtqYPedZ0faILPpIEjA5xx56Cw38gOz02RBE10W5ld7-AX1ksTCx1gvJ-srzRPNfITUEmUf2qUD5o1Cj/s1600/Cyclostem5.jpeg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="158" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhLGwgqNdE-QdAVtL61wkkdmOFv2eDDQazmnMlEq959sZND0shUaDDbIRPJEnb8xtqYPedZ0faILPpIEjA5xx56Cw38gOz02RBE10W5ld7-AX1ksTCx1gvJ-srzRPNfITUEmUf2qUD5o1Cj/s400/Cyclostem5.jpeg" width="400" /></a></div><br />
Here is an annotated example that has been featured here before. The wrinkles (<b>W</b>) and the impression of the stem (<b>S</b>) are clearly visible and have been caused by the stem and frond being pushed over by a strong current which eventually deposited the overlying sand bed<br />
<br />
The explanation of the "mop" structures is a neat use of the interplay between sedimentology and taphonomy, that ties together a number of structures.<br />
<br />
<span style="font-size: x-small;">Tarhan, L.G., Droser, M.L. and Gelhing, J.G (2010) Taphonomic Controls on Ediacaran Diversity: Uncovering the Holdfast Origin of Morphologically Variable Enigmatic Structures. <i>Palaios</i> V. 25, pp 823-830. <a href="http://palaios.geoscienceworld.org/cgi/content/abstract/25/12/823">DOI:10.2110/palo.2010.p10-074r</a></span>Chris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.com0tag:blogger.com,1999:blog-5517176012861550589.post-51599354909787774412011-04-01T00:11:00.000+11:002011-04-01T00:11:16.825+11:00New Find Challenges EvolutionI've been a passionate supporter of evolution, but now . . . <br />
<br />
A recent find from the Flinders Ranges of South Australia will shake the theory of evolution to the core. But no-one knows about it.<br />
<br />
Why?<br />
<br />
I've tried to talk to palaeontologists about it, but the refuse to discuss it. Evolutionists I've known for years no longer reply to my emails. I've been ignored buy organising committees for conferences and symposiums in favour of other evolutionists when I have earth shattering evidence against their pet theory.<br />
<br />
They may have frozen me out, but I will not be silenced.<br />
<br />
From a Precambrian site deep in the Flinders Ranges, I was guides by something . . . or someone, and I found startling remains - reptile remains with clear preservation of skin. How could that be if the 'so called' (in my opinion now) theory of evolution is true? How can exceptionally preserved reptile remains be present at a Precambrian site?<br />
<br />
It can't. But it is. So evolution must be false.<br />
<br />
Click on the link below and spread the evidence the the evolutionists have tried to stop me from exposing. <br />
<br />
Reptiles in the Precambrian disproves evolution<br />
<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhe6n7NGpUxp3Nk1Kb9cQMznruVukJD9ZqTb1Rvd90i9Rz36x2IHeDphgZNwLusAQX6q0fpN5Llq8jP21gd4ZLGfd-J5NX7-9sM3AGNX_de0n5T-aSRY6aib0BueQo6G3Ex8D6pneBPyPD_/s1600/Ediacaran+dead+lizard.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="10" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhe6n7NGpUxp3Nk1Kb9cQMznruVukJD9ZqTb1Rvd90i9Rz36x2IHeDphgZNwLusAQX6q0fpN5Llq8jP21gd4ZLGfd-J5NX7-9sM3AGNX_de0n5T-aSRY6aib0BueQo6G3Ex8D6pneBPyPD_/s200/Ediacaran+dead+lizard.jpg" width="20" /></a></div>Chris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.com8tag:blogger.com,1999:blog-5517176012861550589.post-22178169186434493622011-02-17T13:59:00.000+11:002011-02-17T13:59:49.384+11:00Paris Feb 2011Something told me I'd picked the wrong day to check out the view from the top of the Eiffel Tower . . .<br />
<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhgz7CF_7lhYj0MyuU-G8cbg6KTd8XGeJddVPQ8bZxTuwYgcbAy4e_cXHywvzeCCMzVFrtkLYsXtbkoojBw784iEp6YiVZrjGIVRe51xS1MPSsEjqCXqdKk7HpZHBwg1rwE5dJQw5dBdwsa/s1600/Eiffel1.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhgz7CF_7lhYj0MyuU-G8cbg6KTd8XGeJddVPQ8bZxTuwYgcbAy4e_cXHywvzeCCMzVFrtkLYsXtbkoojBw784iEp6YiVZrjGIVRe51xS1MPSsEjqCXqdKk7HpZHBwg1rwE5dJQw5dBdwsa/s400/Eiffel1.jpg" width="400" /></a></div><br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh5dmIks__st-XMNwkloHY-vl7C41zWIvHL_yXsNse3Pq-Q757qJ2VTQHwPs1YOBe9Cotika8VbpbHJ-92BA0cCEqproD1IWut-DYeUsVv7t2ZbDZ1MrOEju1sRCViEI-SsPVdEqGuucNne/s1600/Eiffel2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh5dmIks__st-XMNwkloHY-vl7C41zWIvHL_yXsNse3Pq-Q757qJ2VTQHwPs1YOBe9Cotika8VbpbHJ-92BA0cCEqproD1IWut-DYeUsVv7t2ZbDZ1MrOEju1sRCViEI-SsPVdEqGuucNne/s400/Eiffel2.jpg" width="300" /></a></div>Chris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.com1tag:blogger.com,1999:blog-5517176012861550589.post-6384249925472037042011-02-02T21:13:00.005+11:002011-03-06T13:44:15.128+11:00Palaeoporn 22<center><span style="font-size: large;"><i>Treptichnus pedum</i></span></center><br />
<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjQ-jGKc8wkqc-3ATd470g7N7Auu-gI8CnvArkmt2e3eQqo8xYSFmz3vZxVOJPjPtD_UfoAfN4oYQ7_CLPGBwGO3W39aa-2W23qCU0QeTrZZFjzsrjI0PWsn6-JD7ICken-kwDQ-rpDH_Gu/s1600/Treptichnus1.jpeg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjQ-jGKc8wkqc-3ATd470g7N7Auu-gI8CnvArkmt2e3eQqo8xYSFmz3vZxVOJPjPtD_UfoAfN4oYQ7_CLPGBwGO3W39aa-2W23qCU0QeTrZZFjzsrjI0PWsn6-JD7ICken-kwDQ-rpDH_Gu/s400/Treptichnus1.jpeg" width="389" /></a></div><br />
The type section for the Cambrian-Precambrian boundary is at Fortune Head, Burin Peninsula, Newfoundland, as is marked by the first appearance of the trace fossil <i>Treptichnus pedum</i> (the trace fossil formally known as <i>Phycoides pedum</i>).<br />
<br />
<i>Treptichnus pedum</i> is a distinctive burrow pattern comprised of a series of lobes set along a central, sometimes curved burrow, thought to represent successive probes into the sediment searching for food. The traces are thought to represent an organism more complex that those of the Ediacaran, but that is not necessarily true, as no actual animal has been found is association with the burrows, so we don't know what made them (although modern <a href="http://en.wikipedia.org/wiki/Priapulida">priapulid worms</a> make similar burrows).<br />
<br />
However, we should not confuse the somewhat complicated pattern of <i>Treptichnus pedum</i> with the first occurrence of well-developed, fairly complex metazoan animals.<br />
<br />
While the start of the Cambrian is marked by the first appearance of <i>Treptichnus pedum</i>, this is not the first appearance of trace fossils probably from metazoans. A number of trace fossil types exist in the preceding Ediacaran rocks. In fact they show a neat line in increasing complexity from simple traces early in the Ediacaran to traces as complex as <i>T. pedum</i> towards the end of the Ediacaran.<br />
<br />
The earliest traces we have, and the most simple, is <i>Planolites</i><br />
<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhvGdZqr-ewBOTTRnAX5F5tgT8KEVz7FzTBT3y9LHK2BrloTI4sH2CtA4aMcfxm62B05m69uQCa1C97SCLlNdds73gY0jo_pi3RlqLj_jL7ZSJRfRV2jLXv_GWg2h4OR8L0SzMIshVjWivf/s1600/Planolites.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="298" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhvGdZqr-ewBOTTRnAX5F5tgT8KEVz7FzTBT3y9LHK2BrloTI4sH2CtA4aMcfxm62B05m69uQCa1C97SCLlNdds73gY0jo_pi3RlqLj_jL7ZSJRfRV2jLXv_GWg2h4OR8L0SzMIshVjWivf/s400/Planolites.jpg" width="400" /></a></div><br />
This is a lowermost Cambrian specimen (picture from <a href="http://ncse.com/image/wmtraceburrows">NCSE</a>), but it shows you what they are like. The fossil is of simple, cylindrical, unbranched and unlined burrows. They are usually sinuous and undulatory, and often appear as small knobs or discontinuous segments on bedding planes. The small image below is what they typically look like in Ediacaran rocks<br />
<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0DAGA0ovQ__lSImLHjdvwxTwBbX7sdwWGQP6jJlBXI-jy6-nv8iFL8-fDpOpc4nOHOsQzMj0HhdtrF_yMnPi9PvmCHCEZ9vnX1Vzn4AfIpZXJEq8Cn6lARnGUgvF9zLP3reE45nzrxesH/s1600/Planolites1.jpeg" imageanchor="1" style="margin-bottom: 1em; margin-left: 1em;"><img border="0" height="163" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0DAGA0ovQ__lSImLHjdvwxTwBbX7sdwWGQP6jJlBXI-jy6-nv8iFL8-fDpOpc4nOHOsQzMj0HhdtrF_yMnPi9PvmCHCEZ9vnX1Vzn4AfIpZXJEq8Cn6lARnGUgvF9zLP3reE45nzrxesH/s400/Planolites1.jpeg" width="145" /></a></div><br />
Further up in the Ediacaran, more traces appear. This is <i>Helminthopsis</i><br />
<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhyuWVoXaky8kWPaRmEa9bFZ8t60nU1lBvR-qh0NTtldwWaYtoG9Sbo8s3UhK20REStKVBGbFUHdOaG5kUTBJ0SBaigyOo46ef7JPgbOQiKoeUPW0E9tVsw2OAwZg9Dj9Y3GUNGDagS_C_e/s1600/Ediacaran+Helminthopsis+canada1.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="259" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhyuWVoXaky8kWPaRmEa9bFZ8t60nU1lBvR-qh0NTtldwWaYtoG9Sbo8s3UhK20REStKVBGbFUHdOaG5kUTBJ0SBaigyOo46ef7JPgbOQiKoeUPW0E9tVsw2OAwZg9Dj9Y3GUNGDagS_C_e/s400/Ediacaran+Helminthopsis+canada1.jpg" width="400" /></a></div><br />
<i>Helminthopsis</i> are much more meandering burrows that appear to represent shallow feeding burrows. the distinctive whorls and loops are considered to represent a different feeding strategy to that of <i>Planolites</i>.<br />
<br />
Towards the top of the Ediacaran, things get a bit more complex. As well as <i>Planolites</i> and <i>Helminthopsis</i>, we get the feeding traces of <i>Kimberella</i>.<br />
<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh1AneuCykbHLPUp-iS_EhY3hPwW0dnTGQqh1DxEUQiVuzVVfuWZc62qkIqtbELciQY-mp-KXbh9sYkAMUwxUHERm0lj8jXqxT-YLfAj_NykTY_h0f9-d99g9IHry6oCfVwusJeDZEGl2pw/s1600/Ediacaran+radula2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="272" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh1AneuCykbHLPUp-iS_EhY3hPwW0dnTGQqh1DxEUQiVuzVVfuWZc62qkIqtbELciQY-mp-KXbh9sYkAMUwxUHERm0lj8jXqxT-YLfAj_NykTY_h0f9-d99g9IHry6oCfVwusJeDZEGl2pw/s400/Ediacaran+radula2.jpg" width="400" /></a></div><br />
Here, the feeding traces are marked "<b>R</b>" for radula, and the animal itself is marked "<b>K</b>". A <i>Dickinsonia</i> is also present. "<b>K'</b>" and "<b>D'</b>" mark the resting trace of <i>Kimberella</i> and <i>Dickinsonia</i>, which comprise, of course, another form of trace fossil.<br />
<br />
Towards the top of the Ediacaran, things start to get crowded. Not only do we have all the previous traces, but they are joined by <i>Mattaia miettensis</i>.<br />
<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgJtS-CakNriJZuV7Ho7r7qXhLnqCfrgU9zZTS5Ou17oP1iYx90G3xemRWPo1zo3VmpBbRnmL1AgnCdAZJplDCPehZaDCi2AMQpbwtkMN8C_jQAeQ2aFTnW5k6HKkhXMpC1MRnY-6Wk-dq2/s1600/Mattaia.jpeg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgJtS-CakNriJZuV7Ho7r7qXhLnqCfrgU9zZTS5Ou17oP1iYx90G3xemRWPo1zo3VmpBbRnmL1AgnCdAZJplDCPehZaDCi2AMQpbwtkMN8C_jQAeQ2aFTnW5k6HKkhXMpC1MRnY-6Wk-dq2/s400/Mattaia.jpeg" width="372" /></a></div><br />
This <a href="http://www.paleo.pan.pl/people/Dzik/Pubications/Verdun.pdf">specimen</a> comes from the Kessyusa Formation, from Khorbusuonka in northern Siberia. The trace is filled with two bands of sediment, raised on the sides and depressed in the middle, where the bands are separated by a vertical fissure filled with clay. A possible culprit is a pripulid worm such as the Burgess Shale form <i>Louisella pedunculata</i>.<br />
<br />
So by the time you get to the Cambrian-Precambrian boundary there were quite a few traces around. Sure in the Cambrian the traces get much more diverse, but they don't start at the boundary, there is a steady increase in trace fossils through the Ediacaran.<br />
<br />
<hr /><b>Update</b><br />
Aleksey Nagovitsyn has kindly informed me that the age range for <i>Mattaia miettensis</i> in Palaoeporn 22 is incorrect, and <i>Mattaia miettensis</i> is <a href="https://picasaweb.google.com/alnagov2/Khorbusuonka?authkey=Gv1sRgCNzZnu7G85bdoQE#5580658803045886546">actually</a> to be found in the Cambrian Tommotian Stage of the Cambrian. <br />
<br />
So we need to remove <i>Mattaia miettensis</i> from the list of trace fossils found at the top of the Ediacaran.Chris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.com6tag:blogger.com,1999:blog-5517176012861550589.post-5364317736609042122011-01-14T18:36:00.004+11:002011-01-14T19:00:18.585+11:00"You Cannot Trust Reasons to Believe"At least that's what <a href="http://toddcwood.blogspot.com/">Todd Wood</a> thinks.<br /><br />In a series of detailed posts, Todd does an excellent job of taking apart a series of posts and responses by Dr Fuzale Rana of <i>Reasons to Believe</i> (a christian group that "bridges the gap between science and faith by exploring questions about God and the Bible". They have no problem with an ancient Earth, but evolution is apparently another matter) on the similarity between the human and chimp genome (or not, in the case of Reasons to Believe) and moves on to pseudogenes, thus:<br /><blockquote>"In his latest post, Rana asserts the following about the argument for common ancestry from pseudogenes:<br /><br /><i>When evolutionary biologists present this argument, they make a number of assumptions, all of which appear to have questionable validity based on recent research results. For the pseudogene evidence to have potency: (1) pseudogenes must lack function; (2) their origin must be due to rare, random events; and (3) their juxtaposition to other genes must be arbitrary.</i><br /><br />Everything he wrote there is utterly false. None of those conditions are required to argue for common ancestry from pseudogene similarity. Not one."</blockquote>Ouch!<br /><br />Well, you may say, 'showing up the mangling of science by those seeking to support their religious views, is not unusual".<br /><br />True. But Todd happens to be a young earth creationist.<br /><br />Double ouch!<br /><br />Here is post <a href="http://toddcwood.blogspot.com/2011/01/rtb-and-chimp-genome-part-1.html">one</a>, from there move on to "Newer Post" and read them in sequence. Post four is at the bottom of the front page of Todd's blog. You can work your way up. <br /><br />It's well worth the read.Chris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.com2tag:blogger.com,1999:blog-5517176012861550589.post-19116955803882655772011-01-09T13:39:00.010+11:002011-01-09T16:09:12.513+11:00Palaeoporn 21<center><i><b>Beltanelliformis brunsae</b></i></center><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmdLMultxpNvTrFKbG3uCYAUPeD5iS3amkNQU_u58J0LEHbndjdNbxGSBugSn5e57qNQXlQSYlOX5riy2tf8x7DuJWho21jgj_9kG8DdkXP_Ieoc42-3K56c75geyvOpUmQ9CbAgTQWjbZ/s1600/Beltanelliformisannot.jpeg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 285px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmdLMultxpNvTrFKbG3uCYAUPeD5iS3amkNQU_u58J0LEHbndjdNbxGSBugSn5e57qNQXlQSYlOX5riy2tf8x7DuJWho21jgj_9kG8DdkXP_Ieoc42-3K56c75geyvOpUmQ9CbAgTQWjbZ/s400/Beltanelliformisannot.jpeg" alt="" id="BLOGGER_PHOTO_ID_5560010487922480130" border="0" /></a><br />In keeping with the positive hyporeliefian, is-it-or-isn't-it-a-metazoan theme of the last couple of posts, here is <i>Beltanelliformis brunsae</i>. A widespread form (this one is from the Mackenzie Mountains of Canada) that has had a history of being moved around the tree of life.<br /><br />Notice firstly the texture of the surface. This is a microbial mat that has undergone some considerable deformation, probably due to the sudden influx of sand which pressed down on the mat and caused it react unevenly to the sudden load.<br /><br />The <i>Beltanelliformis</i> appear at first glance to be similar to other disc-like Ediacaran forms associated with holdfasts. However, notice that the specimens pictures are in strong <a href="http://ediacaran.blogspot.com/2011/01/to-epirelief-or-hyporelief-that-is.html">positive hyporelief</a>, that is they extend quite some way out from the lower surface of the sandstone. This means that the sand infilled quite a sizable hole in the underlying mud. Notice also that, in the top two specimens, the fossil has a 'collar' around the basal disc, which makes the hole infilled by the sand cone-shaped, with the base being the smaller diameter part of the cone.<br /><br />This configuration let to <a href="http://books.google.com.au/books?id=jMPfQoFNr-IC&pg=PA391&lpg=PA391&dq=Beltanelliformis&source=bl&ots=s1kbYFKVgj&sig=VtZuA6Dy6JG9iipjJFXLb3Pxun4&hl=en&ei=wAspTfLpDYbuvQOj3qzYAQ&sa=X&oi=book_result&ct=result&resnum=6&ved=0CDoQ6AEwBQ#v=onepage&q=Beltanelliformis&f=false">suggestions</a> that the form represents the burrow of an anemone.<br /><br />Below is a representation of that interpretation (from <a href="http://books.google.com.au/books?id=jMPfQoFNr-IC&pg=PA391&lpg=PA391&dq=Beltanelliformis&source=bl&ots=s1kbYFKVgj&sig=VtZuA6Dy6JG9iipjJFXLb3Pxun4&hl=en&ei=wAspTfLpDYbuvQOj3qzYAQ&sa=X&oi=book_result&ct=result&resnum=6&ved=0CDoQ6AEwBQ#v=onepage&q=Beltanelliformis&f=false">Schopf <i>et al.</i></a>).<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhWJjFX4zDqEroyCYPMI1_V892FZVNSxC7vLtZozSLTT36GF8c8kyI5bgD2-vHJk5VBsTHnq6uqm9GkHfvsKDrH8PS9-vUD9anRf2JQOin4lpSvIbOVMSkljUipiALTSbm1cBSeXtGKr48d/s1600/Beltanelliformisdia.jpeg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 308px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhWJjFX4zDqEroyCYPMI1_V892FZVNSxC7vLtZozSLTT36GF8c8kyI5bgD2-vHJk5VBsTHnq6uqm9GkHfvsKDrH8PS9-vUD9anRf2JQOin4lpSvIbOVMSkljUipiALTSbm1cBSeXtGKr48d/s400/Beltanelliformisdia.jpeg" alt="" id="BLOGGER_PHOTO_ID_5560015189101714098" border="0" /></a>However, more recent interpretations have <i>Beltanelliformis</i> as an algae.<br /><br />What!? Algae!?<br /><br />Yes, algae. Here's why.<br /><br />The uppermost Doushantuo Formation (590-555 Ma) at Miaohe in the Yangtze Gorges area, is a series of dolomites that provide a rare Burgess-Shale-type taphonomic window on the Ediacaran. Within the Formation are found numerous carbonate compressions of organisms. This represents a different mode of preservation to that of the more typical sandstone preservation, at Miaho the forms are flattened carbonate compressions. Amongst the forms present are several that are interpreted as <i>Beltanelliformis</i><br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjOhh6nJv__iqGUVErBAb_Z6lWSHfW7CNJMviUSvxvlXdiRMPyQxB-g-_5G5A6r3h2svOak2zOO3F1WyubFbfq2X5YQlR_gj70GGj3HufNJBI3IMDSVNhVGrBOgAs-0XH3WnC-eOzmIsJrU/s1600/Beltanelliformischinaannot.jpeg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 220px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjOhh6nJv__iqGUVErBAb_Z6lWSHfW7CNJMviUSvxvlXdiRMPyQxB-g-_5G5A6r3h2svOak2zOO3F1WyubFbfq2X5YQlR_gj70GGj3HufNJBI3IMDSVNhVGrBOgAs-0XH3WnC-eOzmIsJrU/s400/Beltanelliformischinaannot.jpeg" alt="" id="BLOGGER_PHOTO_ID_5560041241722899874" border="0" /></a><blockquote><span style="font-size:85%;"><i>Beltanelliformis brunsae</i> from the Doushantuo Formation. Scale in 2, 1 cm. from <a href="http://www.paleo.geos.vt.edu/shahai/Reprints/XiaoMiahoBiotaJP2002.pdf">Xiao <i>et al.</i> 2002</a>)</span></blockquote>The non-overlapping nature of the fossils is a good indication that we are dealing with benthic (bottom-dwelling) forms and not free-swimming forms that have died and sunk to the bottom. It may well be that the forms were actually tethered to bottom with a small holdfast structure.<br /><br />The Doushantuo specimens have thing flexible walls. However, given the original specimen at the beginning of this post, it's clear that they would need to retain the three-dimensional shape during burial by sand.<br /><br />A modern form that appears to fit the bill is the caulerpalean green alga <i>Derbesia</i> (<a href="http://www.reefcleaners.org/index.php?option=com_content&task=view&id=54&Itemid=81">photo credit</a>).<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4hSVFj39I-ku0zdM2EmIVHeKTycVJ4ST_uaMMj4FelOUW8zdZU0FnxOC_YJd-hIjuOh5fSKxVnEsdQtqExYPLuKUDNjsRSzbyTsv6Vp4uDw8-camz0A5QqlcjjptnOD1uRIN9oVqjqOgm/s1600/derbesia.jpg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 267px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4hSVFj39I-ku0zdM2EmIVHeKTycVJ4ST_uaMMj4FelOUW8zdZU0FnxOC_YJd-hIjuOh5fSKxVnEsdQtqExYPLuKUDNjsRSzbyTsv6Vp4uDw8-camz0A5QqlcjjptnOD1uRIN9oVqjqOgm/s400/derbesia.jpg" alt="" id="BLOGGER_PHOTO_ID_5560040465661374530" border="0" /></a><br /><i>Derbesia</i> is benthic, is attached by a minute holdfast, and has the right shape and size. Also, it is organized as a coenocytic film of cytoplasm within a elastic and strong wall and surrounding one or more large, fluid-filled vacuoles. These vacuoles would be sealed and so couldn't empty on burial like holdfasts could. This makes it strong enough to make an impression in sandstone preservation!<br /><br />So <i>Beltanelliformis</i> has gone from Cnidarian -> holdfast -> anemone burrow -> algae with holdfast.<br /><br />Interestingly, apart from <i>Nimbia</i> and <i>Aspidella</i> mentioned in a <a href="http://ediacaran.blogspot.com/2011/01/770ma-ediacara-fossils-from-kazakhstan.html">previous post</a>, <i>Beltanelliformis</i> has one of the longest time ranges, having been found in the pre-Ediacaran Cryogenian in Canada.<br /><br />This again raised the possibility that several of the generic Ediacaran disc fossils could be something other than metazoans. That's actually fine. We have enough evidence that <b>some</b> of the discs represent metazoans. That some don't, should be expected. After all, if the Ediacaran assemblages represent vibrant, healthy ecosystems, they would be expected to contain microbial, algal, and metazoan, life.Chris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.com0tag:blogger.com,1999:blog-5517176012861550589.post-43262768647958506032011-01-03T23:37:00.011+11:002011-01-04T00:44:28.243+11:00To Epirelief or Hyporelief, That is the Question . . .My last post on the possible <a href="http://ediacaran.blogspot.com/2011/01/770ma-ediacara-fossils-from-kazakhstan.html">770 million year old Ediacaran fossils from Kazakhstan</a> prompted some comments regarding epi- and hyporelief (go read the post and comments).<br /><br />Basically, Ediacaran fossils are usually found on the underside of the sandstone bed in either positive relief (sticking out from the surface) or negative (sunk into the surface) hyporelief (hypo- is sciencey for 'on the underside'). This is dictated by the mode of preservation (again see the original post), and means that we do not find them on the top surface of the sandstone bed, or in epirelief. (Actually we do find them in epirelief, but only at Mistaken Point in Newfoundland where they have been mantled by volcanic ash - but that appears to be a one off and so does not represent normal preservation).<br /><br />As an example here is a slab I collected from the Flinders Ranges in South Australia. First the upper (epi) surface.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjxMXkfNIj28wV9aLyp8B3c0V4FKl6NpSPRntXbVTAk13Ik2ziuNTutYtl7kUIgAUXYE0zy12zbyRJKM2r1879Ia5LxzGs-9_giJR76HJM-6ej9koCjd6fbPDbSNohh2cKngPrEk9HvZlVF/s1600/Ediacaranslab1anno.jpeg"><img style="display:block; margin:0px auto 10px; text-align:center;cursor:pointer; cursor:hand;width: 400px; height: 262px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjxMXkfNIj28wV9aLyp8B3c0V4FKl6NpSPRntXbVTAk13Ik2ziuNTutYtl7kUIgAUXYE0zy12zbyRJKM2r1879Ia5LxzGs-9_giJR76HJM-6ej9koCjd6fbPDbSNohh2cKngPrEk9HvZlVF/s400/Ediacaranslab1anno.jpeg" border="0" alt=""id="BLOGGER_PHOTO_ID_5557946557971603154" /></a><br />As you can see, its rippled - strongly rippled actually - which puts pay to the ideas that the Ediacaran faunas were deep water, but that's another story. However, what the top surface isn't, is fossiliferous. There are no fossils on it. <br /><br />Now lets take a look at what's underneath.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj53uz-6pwIUQmg592oHpbq1VqsCHWEb6EiTReH4w1NiWvg-_jXrBxRTGTNLw65lyjztdT1gGIBoI2n7QZDoXfNBqzVYtHDT-dGLmOR74FMan-h3OTOYDvu327HJgXd0dNH5JGFrWdvLGOI/s1600/Ediacaransab012011.jpeg"><img style="display:block; margin:0px auto 10px; text-align:center;cursor:pointer; cursor:hand;width: 400px; height: 262px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj53uz-6pwIUQmg592oHpbq1VqsCHWEb6EiTReH4w1NiWvg-_jXrBxRTGTNLw65lyjztdT1gGIBoI2n7QZDoXfNBqzVYtHDT-dGLmOR74FMan-h3OTOYDvu327HJgXd0dNH5JGFrWdvLGOI/s400/Ediacaransab012011.jpeg" border="0" alt=""id="BLOGGER_PHOTO_ID_5557949522634110258" /></a><br />Ta Da! This was taken <i>in situ</i>, about 5 minutes after I'd found it. The photo is a bit blurry 'cos my hands were stili shaking!<br /><br />Notice the smooth lower surface. This is because it is mantling a mud which does not form ripples. Also notice that there are three large discs in positive hyporelief and a <i>Dickinsonia</i> in negative hyporelief. What do you mean no!?. Ok, here's an annotated version.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiPdtHPR2V4_bT_CJq9Durlupd9xc54zry_siVkQ4KLvS9HkmA3BWsA8bOi5-ok6VwzYmLThBqs6Zx_vsieBwSXgq9a7o8z303UarNtPrmH0eskCwZ9ScYn7y4Ntabngto4nBVJZ_DqAR7B/s1600/Ediacaranslabanno.jpeg"><img style="display:block; margin:0px auto 10px; text-align:center;cursor:pointer; cursor:hand;width: 400px; height: 262px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiPdtHPR2V4_bT_CJq9Durlupd9xc54zry_siVkQ4KLvS9HkmA3BWsA8bOi5-ok6VwzYmLThBqs6Zx_vsieBwSXgq9a7o8z303UarNtPrmH0eskCwZ9ScYn7y4Ntabngto4nBVJZ_DqAR7B/s400/Ediacaranslabanno.jpeg" border="0" alt=""id="BLOGGER_PHOTO_ID_5557947712163437346" /></a><br />The question has been asked why the counterpart of a positive hyporelief isn't a negative epirelief on the bed below. In other words if the fossil is formed by sand flowing into a depression in the underlying mud to form a positive hyporelief, should there also be a corresponding negative epirelief on the top of the underlying bed? <br /><br />The answer is yes, but we almost never find them. The reason is that the underlying bed is made of mud and so compresses during diagenesis which disrupts the fossil. However, the main reason is that the mudstone weathers much more readily than the sandstone and forms a very friable, crumbly rock that simply weathers away.<br /><br />We do have some examples of underlying epirelief fossils, but they are very rare. To find them you have to excavate the sandstone with the underlying mudstone still in place. Even then, they are very fragile. Normally this never happens in nature as the mudstone erodes away. The fossiliferous sandstone then weathers out and falls downslope to be found by palaeontologists.<br /><br />Below is a typical Ediacaran location. The fossils are eroding off the top of the hill and can just be seen in outcrop. but the fossils are found on the scree slope, as float - that is, material that has eroded out of the outcrop and has slid downslope<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiVKY5jylX6gNO_SeGZFiQIbmzRitF8ystlK6G0f_y0uqqzoSDi-hs-CtNW8I6Iai97fUuCRKETlDa1E4n5OkQvQe5hrDWkL2veMIEvK_6YRTv4TzpIN_irnFF-KeK2v9ko9CV1a4ySh0rJ/s1600/Ediacaransite.jpeg"><img style="display:block; margin:0px auto 10px; text-align:center;cursor:pointer; cursor:hand;width: 400px; height: 259px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiVKY5jylX6gNO_SeGZFiQIbmzRitF8ystlK6G0f_y0uqqzoSDi-hs-CtNW8I6Iai97fUuCRKETlDa1E4n5OkQvQe5hrDWkL2veMIEvK_6YRTv4TzpIN_irnFF-KeK2v9ko9CV1a4ySh0rJ/s400/Ediacaransite.jpeg" border="0" alt=""id="BLOGGER_PHOTO_ID_5557952316061272674" /></a><br />So the answer is, yes there are there epirelief fossils but we almost never find them as they have weathered away. But they would be in mudstones and not in sandstones.Chris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.com1tag:blogger.com,1999:blog-5517176012861550589.post-83210706270033117602011-01-02T16:53:00.000+11:002011-01-02T16:54:29.162+11:00770Ma Ediacara (?) Fossils from Kazakhstan (sadly no)<span style="float: left; padding: 5px;"><a href="http://www.researchblogging.org/"><img alt="ResearchBlogging.org" src="http://www.researchblogging.org/public/citation_icons/rb2_large_gray.png" style="border: 0pt none;" /></a></span>The Ediacaran Period represents that youngest part of the <a href="http://en.wikipedia.org/wiki/Proterozoic">Proterozoic</a>, and is famous for the first appearance of multicellular, metazoan fossils. The Period starts at the end of the great neoProterozoic <a href="http://en.wikipedia.org/wiki/Cryogenian">Cryogenian</a>, or glaciations - commonly called "Snowball Earth" - at around 635 million years ago, and ends at the start of the Cambrian (and <a href="http://en.wikipedia.org/wiki/Phanerozoic">Phanerozoic</a>) at around 542 million yeras ago. While a few Ediacaran stragglers may appear in the Lower Cambrian, no unambiguous multicellular/metazoan fossils have been found below the base of the Ediacaran Period, despite several possible candidates (e.g <a href="http://ediacaran.blogspot.com/2010/07/21-ga-multicellular-colonial-organisms.html">here</a> and <a href="http://ediacaran.blogspot.com/2010/09/proterozoic-sponges-claim-doesnt-hold.html">here</a>).<br /><br />In a <a href="http://dx.doi.org/10.1016/j.gr.2010.11.008">new paper</a>, Meert <i>et al.</i> report the possible occurrence of Ediacaran fossils from 760-770 million year old Cryogenian rocks of Kazakhstan. If correct, this would extend the fossil record of metazoans back another 100 million years. Now, there is some <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1472-4669.2009.00225.x/abstract">evidence</a> to suggest that metazoans were around in the Cryogenian, if only at the sponge-grade of organisation, but this is from biochemistry, not body fossils. So this would be the oldest metazoan body fossils yet found.<br /><br />Two questions to be asked then. Are these deposits c. 770 million years old? Are these specimens examples of Ediacaran fossils?<br /><br />I think the answer to the first question is yes, and the answer to the second question is no. I'll explain below.<br /><br /><b><u>Age</u></b><br />I have to say that Meert <i>et al.</i> have done an excellent job of mapping and correlating what appears to be a very difficult sequence. It's condensed and so quite thin (by contrast, the Ediacaran type section in Australia is several kilometres thick), a significant portion missing, and the area has been subsequently affected by tectonics.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi0dvcn0mNQEUp8R8bRbi8AY51XdwHT2smYDHFTTnwA6uigyE4Xw5FxIbF16GJYVSPK6BwplHMYJ9cKqEutCsV8Jx8adsgA4dg9XOpD8y1nTqbcFiTEUDsBBK9IABwfcg-Shc6j7AeJk8MQ/s1600/Meertstrat.jpeg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 362px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi0dvcn0mNQEUp8R8bRbi8AY51XdwHT2smYDHFTTnwA6uigyE4Xw5FxIbF16GJYVSPK6BwplHMYJ9cKqEutCsV8Jx8adsgA4dg9XOpD8y1nTqbcFiTEUDsBBK9IABwfcg-Shc6j7AeJk8MQ/s400/Meertstrat.jpeg" alt="" id="BLOGGER_PHOTO_ID_5556341819210662034" border="0" /></a><blockquote><span style="font-size:85%;">Stratigraphic column for the Lesser Karatau sequence showing the relative locations of the fossil discoveries. The fossils under discussion are from the Upper Riphean Kurgan Formation (R3) (in brown) and the glacial deposits (in yellow) and cap carbonate represents the end of the Cryogenian glacial episode and the start of the Ediacaran Period. (<a href="http://dx.doi.org/10.1016/j.gr.2010.11.008">Meert <i>et al.</i> 2010</a>)</span></blockquote>Now with a section like this it could be argued that the glacial rocks and cap carbonate represent glacial activity known to occur in the Ediacaran and that the underlying rocks are, in fact, Ediacaran. But I think Meert <i>et al.</i> have compiled enough evidence to support their stratigraphy. This includes radiometic dating of two separate samples from the Kurgan Formation that support a c. 770 million year age, as well as a δ13C stable isotopic curve that fits their interpretation (given the fragmentary nature of the curve, it could fit a number of scenarios, but it does fit this one.)<br /><br />So notwithstanding the difficulties of the section, the date appears well supported. We appear to be dealing with c. 770 million year old rocks.<br /><br /><b><u>Fossils</u></b><br />1) Disc and stalk<br />Meert <i>et al.</i> have found structures in the c. 770 million year old Kergan Formation which they suggest may be referable to the Ediacaran forms <i>Nimbia</i> and <i>Aspidella</i>, as well as a second line of evidence, a possible stem extension emanating from the discoid fossil, and ask the question, are these Ediacaran fossils? As I said, I think the answer is no.<br /><br />To show why, firstly I need to explain a bit about Ediacaran fossil preservation and positive/negative epi/hyporelief.<br /><br />Ediacaran fossils occur primarily as marking on the surface of sandstones. These surface markings can be of two types, positive - standing up from the surface like a pimple, or negative - a depression in the surface like a dimple. Also the sandstone has two surfaces, a top surface - the epi-, and a lower surface - the hypo. Thus when we talk about surface structure, or "relief" - we talk of structure on the top bedding surface - epirelief, and structure on the lower bedding surface - hyporelief. So positive epirelief is a raised area on the top surface and negative hyporelief is a depression in the lower surface.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhWqQl-hdogUkarHdebWQLHux086uYl02M2NqGUBJuVBF82V5JXgyrQ4L0Q3cQOAbJ0eN6To-_2lk14RNO_Gn5jjPouewRS-LKWite9racupoQni4HwPahY6Ir-hFylhOosNRl0t1bXE-V3/s1600/epihypo.jpeg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 320px; height: 168px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhWqQl-hdogUkarHdebWQLHux086uYl02M2NqGUBJuVBF82V5JXgyrQ4L0Q3cQOAbJ0eN6To-_2lk14RNO_Gn5jjPouewRS-LKWite9racupoQni4HwPahY6Ir-hFylhOosNRl0t1bXE-V3/s320/epihypo.jpeg" alt="" id="BLOGGER_PHOTO_ID_5556340485140758482" border="0" /></a>This is important because Ediacaran fossils occur as positive or negative relief on the bedding surfaces, but almost always as positive or negative hyporelief - that is, on the bottom surface.<br /><br />The reason for this is that preservation is by sand covering a surface that has animals on it. The sand (which will eventually turn into sandstone) covers the animals. Where the animal is tough, it will push into the overlying sand, causing a negative hyporelief impression (of the top surface of the animal) into the bottom surface of the sand. Where the animal is buried in the underlying sediment, such as holdfasts, the sand flows into the depression caused by the collapse of the holdfast during burial, causing a positive hyporelief impression.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjsAFrphOGUEkmrL9Lcgyk5AKheyN5ZKxvbvAltHXqqsc-kkXx5V4iSJmRJKe-dTTTc9OVheeImvURwcRFJ1VG-78U8K6CxS_3NKN8ZsqWI8T8ly7wkS6rTUnCzncyTlId_N0WOk68BSjhX/s1600/posneghypo.jpeg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 329px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjsAFrphOGUEkmrL9Lcgyk5AKheyN5ZKxvbvAltHXqqsc-kkXx5V4iSJmRJKe-dTTTc9OVheeImvURwcRFJ1VG-78U8K6CxS_3NKN8ZsqWI8T8ly7wkS6rTUnCzncyTlId_N0WOk68BSjhX/s400/posneghypo.jpeg" alt="" id="BLOGGER_PHOTO_ID_5556437211245596162" border="0" /></a><br />The example above is of the lower surface, The Form D projects out from the surface and so is a positive hyporelief impression (the overlying sand has pushed down into the Form D <a href="http://ediacaran.blogspot.com/2010_09_01_archive.html">stolon</a> structure to form the impression. By contrast, the <i>Parvancorina</i> has pushed up into the overlying sand and so is preserved as a negative hyporelief impression.<br /><br />OK, lets deal with the second line of evidence first - the possible stem extension emanating from a possible discoid fossil.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjuXMB89vbiSZY4NpM2d7Jyj7KY24LoO7ZCfK2dvh41ERjvQPw0B_PdKfU5E25R-fKVe7Q2idNbfDqg1nrrD8uJwxj27d6iCsRAb7g6W0src9il-4oCOTTeB7QXU_TCAUM2OBgqJojkQMXa/s1600/Meertdisc.jpeg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 382px; height: 400px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjuXMB89vbiSZY4NpM2d7Jyj7KY24LoO7ZCfK2dvh41ERjvQPw0B_PdKfU5E25R-fKVe7Q2idNbfDqg1nrrD8uJwxj27d6iCsRAb7g6W0src9il-4oCOTTeB7QXU_TCAUM2OBgqJojkQMXa/s400/Meertdisc.jpeg" alt="" id="BLOGGER_PHOTO_ID_5556697584744826946" border="0" /></a><blockquote><span style="font-size:85%;">(A) Discoidal impression (negative relief) with possible stem-like extension. (B) Sketch showing the location of discoidal fossil and possible stem. <a href="http://dx.doi.org/10.1016/j.gr.2010.11.008">Meert <i>et al. 2010</i></a>.</span></blockquote> <a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhyGZOmlqlmwrlFDec7jxx0J58a-Za4WF2Vyh6ingtv6HfIepuQVqTsaH2ZjlqPAReJhgET5-VW-C5WB02VBAB_XczFZqlkjy7QIWGh_ChFPci1ncur5IHZlMWut0GIFVNDQjr1pVM7xJnU/s1600/seapen.jpg"><img style="float: left; margin: 0pt 10px 10px 0pt; cursor: pointer; width: 150px; height: 200px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhyGZOmlqlmwrlFDec7jxx0J58a-Za4WF2Vyh6ingtv6HfIepuQVqTsaH2ZjlqPAReJhgET5-VW-C5WB02VBAB_XczFZqlkjy7QIWGh_ChFPci1ncur5IHZlMWut0GIFVNDQjr1pVM7xJnU/s200/seapen.jpg" alt="" id="BLOGGER_PHOTO_ID_5556719221146161442" border="0" /></a> Just to be clear about what is being discussed, here (at left) is a modern sea pen (<a href="http://www.ianskipworth.com/suig/fiordland04-2.html">photo credit</a>) we can use as an example of the frondose forms around in the Ediacaran. The structure half-buried in the sediment is the disc-shaped holdfast. Underneath the holdfast is a thin tube - the peduncle - which acts like the foot of a clam and aids in digging the organism into the sediment. The stem and frond extend out into the water column and the whole thing is held up by water pressure. The organism can inflate by pumping water into the holdfast to allow it to act as an anchor, and also into the stem and frond to hold them rigid. Pumping water out deflates the organism. Modern sea pens will deflate on touching, and collapse down onto the sediment, as a method to avoid predation or damage.<br /><br />According to Meert <i>et al.</i>, their find may represent a holdfast and part of the attached stem that has made an impression in the sediment, in negative relief. The authors do not say if the surface is the top or bottom (and they may not know if the sample was collected loose and not found <i>in situ</i>.<br /><br />However, holdfast impressions are almost always found as <b>positive</b> hyporelief impressions, i.e. they stick out from the lower surface. They are not found as negative relief, i.e. as depressions, as the Kurgan Formation specimen is. To find out why that is, let's look at an example.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgYgXI5qqrADW6nWkT5Yk8x_CBFTigoGRYC-f6Tp41ncD4jAdMjEQsk4zWMuf9-n1a9lciyazP9DY3BOIpMw4c-AsLPCC4M3xglKVYYaga2ixBPSlzmclAVcvaOF70aQKeopliQDQeL86PK/s1600/Cyclostem4.jpeg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 256px; height: 400px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgYgXI5qqrADW6nWkT5Yk8x_CBFTigoGRYC-f6Tp41ncD4jAdMjEQsk4zWMuf9-n1a9lciyazP9DY3BOIpMw4c-AsLPCC4M3xglKVYYaga2ixBPSlzmclAVcvaOF70aQKeopliQDQeL86PK/s400/Cyclostem4.jpeg" alt="" id="BLOGGER_PHOTO_ID_5557068243251480594" border="0" /></a><blockquote><span style="font-size:85%;">Three-dimensional positive hyporelief fossil of a holdfast and stem from the Ediacaran of South Australia. <b>HF</b> impression of holdfast, <b>IS</b> intermediary surface within the sandstone, <b>LS</b> lower surface of sandstone, <b>P</b> peduncle, <b>S</b> impression of stem, <b>W</b> wrinkles in top surface of holdfast. White arrow is the direction of current depositing the sand.</span></blockquote>Above is an actual Ediacaran holdfast and stem fossil. There's a lot going on here (compared with the Meert <i>et al.</i> specimen where no structure is present) so it'll take a bit of explaining.<br /><br />Firstly observe that this is in positive hyporelief - it's on the bottom surface of the bed. As I said, pretty much all holdfast fossils with stems are positive hyporelief. This is because the organism is sitting in the underlying sediment and gets inundated and covered by a mantling sand deposit which will become the overlying sandstone bed. Since frondose forms will deflate on contact with the enveloping sandstone, the organism pumps out water and collapses. This means that the stem falls over, usually in the direction of sand transport. The stem often gets trapped within the sand and rarely comes to rest on the sea floor because the sand has started to deposit as the organism responds. This normally results in the stem coming to rest at an shallow angle to the sea floor/base of the sand body - that is, it sticks up at an angle into the sand rather than laying down flat. This can be seen in the Ediacaran example shown above. The stem impression (<b>S</b>) can be seen heading off at the ten o'clock direction but it is obviously heading off <b>into</b> the sandstone - the edge of the stem impression is lower in the sandstone than the impression of the holdfast, and, as this specimen is shown upside down, the stem in heading <b>upwards</b> into the overlying sandstone.<br /><br />The wrinkling texture is the upper surface of the holdfast reacting to the stem being pushed over and collapsing and shows that the holdfast stayed in place during burial.<br /><br />The organism is now covered by a layer of sand, with the stem trapped within the sand at a shallow angle. As the water has been pumped out, the holdfast will no longer stay inflated and so the holdfast upper surface sinks down onto the lower surface causing a shallow depression. The upper surface also takes on the shape of the lower surface where the hollow peduncle is, creating a ring shape (<b>P</b>). The overlying sand then flows into the shallow depression and takes on the shape of the combined lower and upper holdfast surface structures in a process called gravity casting. Also, as the stem is angled upwards, the sand with collect behind it and be trapped between the stem and the holdfast. We can see this is the example above. The sandstone covering the stem has been removed, leaving a lighter coloured sandstone. The stem starts out on top of the holdfast, but ends up on a lower, intermediate surface (<b>IS</b>) (lower from our prespective, higher when the specimen is rotated to the correct orientation).<br /><br />What you end up with is a positive hyporelief impression of the combined upper and lower holdfast surface, plus the base of the stem. Furthermore, this is the only way this can be preserved. We tend not to see holdfast impressions on the tops of sandstones because the organisms appeared to favour softer, finer sediments such as silts and clays, and where active microbial mats occur.<br /><br />With that in mind lets look at the Meert <i>et al.</i> specimen again.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhtyg4m95OnpcTVhxkk860pJUX5ZWWaxI3xCgVkqyLSwkeA7GrrK_tB76x57N3CHoBr9uo_V4OPTZPqvBCeXiBOKc23TcxabtweE6c7zmsSNyJJgAxlZUw4RK4QeE_MPXaDwtMNq1M21bJZ/s1600/Meertdicanno1.jpeg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 209px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhtyg4m95OnpcTVhxkk860pJUX5ZWWaxI3xCgVkqyLSwkeA7GrrK_tB76x57N3CHoBr9uo_V4OPTZPqvBCeXiBOKc23TcxabtweE6c7zmsSNyJJgAxlZUw4RK4QeE_MPXaDwtMNq1M21bJZ/s400/Meertdicanno1.jpeg" alt="" id="BLOGGER_PHOTO_ID_5557075352250295266" border="0" /></a><br />This time I've annotated it to mark out the various levels in the specimen, with <b>A</b> the highest, <b>B</b> an intermediary level, and <b>C</b> the lowest (assuming we are looking at the top surface, or the reverse if we are looking at the lower surface).<br /><br />First of all, this is a negative relief. As I explained above, holdfast and stem preservation is usually by gravity casting which produces positive relief. If we are looking at a bottom surface, maybe the organism remained intact and 'pumped up', forming a hollow in the overlying sand. But in that case the stem would also remain intact and we wouldn't see the impression of the stem in the resultant fossil. So if the stem is represented, then the organism had collapsed, in which case the holdfast would have collapsed and we would get a positive hyporelief as notmal.<br /><br />The structure can't be a positive hyporelief that has eroded out the produce the depression because the original fossil is just a surface impression. The sandstone underneath the fossil is the same sandstone the rest of the rock and so there can be no preferential weathering to produce the hollow.<br /><br />If we are looking at a top surface, then it is unlikely to be a holdfast and stem as we do not find them on top surfaces of sandstones. Even if it were, the stem appears to have been pushed into the sand body to a level equal to, or even greater than, the depth of the holdfast. Again an unlikely occurrence, as a slight impression on the underlying sand is the most you are likely to get.<br /><br />Given that this is a negative relief and the lack of any distinguishing structure, it is most likely that the specimen is simply an erosional feature and not a fossil.<br /><br />2)<i>Nimbia</i> and <i>Aspidella</i><br />Specimens referable to <i>Nimbia</i> and <i>Aspidella</i> are reported from the c. 770 millio year old Kurgan Formation.<br /><blockquote><i>Our specimens were discovered in a brown-red shale within the largely siliclastic Kurgan Formation and are preserved in both hypo and epi-relief. They are circular to oval-shaped impressions that surround either a smooth interior or circular to oval indentations with a smooth interior.</i> (<a href="http://dx.doi.org/10.1016/j.gr.2010.11.008">Meert <i>et al. 2010</i></a>.)</blockquote><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhSpwUGN_KrgYhirA8W6UPaqlHY6UTh5qyhWHHaSKIH13sBTs_ZAQmYHe3dV2k0C1rTj0dlmtWBEBaAG5ljK1cGpkdAiueD33dpx5VoA83kXM7EmLs7ukF-RW5TDYA4Idk9FDPkLLFnljy/s1600/Meertnimbia.jpeg"><img style="display: block; margin: 0px auto 10px; text-align: center; cursor: pointer; width: 400px; height: 329px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhSpwUGN_KrgYhirA8W6UPaqlHY6UTh5qyhWHHaSKIH13sBTs_ZAQmYHe3dV2k0C1rTj0dlmtWBEBaAG5ljK1cGpkdAiueD33dpx5VoA83kXM7EmLs7ukF-RW5TDYA4Idk9FDPkLLFnljy/s400/Meertnimbia.jpeg" alt="" id="BLOGGER_PHOTO_ID_5557406143465150818" border="0" /></a><blockquote><span style="font-size:85%;">(A) closeup of the <i>Nimbia</i> fossils in positive epirelief, <b>AT</b> marks the occurrence of a possible invaginate morph of <i>Aspidella terranovica</i>; (B) B&W photo of <i>Nimbia</i> impressions shown mostly in positive epirelief; (C) </span><span style="font-size:85%;"><i>Nimbia fossils </i></span><span style="font-size:85%;">in negative relief with a possible invaginate morph of <i>Aspidella terranovica</i> in positive relief; (D) large c. 2 cm (long axis) c. 1.5 cm (short axis) negative hyporelief impression of <i>Nimbia occlusa</i> and an ‘inversion’ of the photo the fossil might appear in positive epirelief. White arrow points to a possible raised central nodule observed in Nimbia occlusa fossils elsewhere. <a href="http://dx.doi.org/10.1016/j.gr.2010.11.008">Meert <i>et al. 2010</i></a>.</span></blockquote> Taking <i>Aspidella</i> first. Actually, attributing the form to <i>Aspidella</i> doesn't tell us much. This is because <i>Aspidella</i> should now be considered a form genus - that is a grouping of similar forms (i.e. discs) and not representative of a single organism, or related group of organisms. In other words, a lot of different things make disc impressions, e.g. algae (algal biscuits), microbial colonies, fungae and metazoans. Calling the specimen <i>Aspidella</i> simply says that it is a certain kind of disc, not that it is the Ediacaran form <i>Aspidella terranovica</i>. There are a lot of morphologies within the <i>Aspidella</i> group and they are not produced by the same organism, or even closely related organisms. This means that more than one organism is included under <i>Aspidella</i>. Even worse, no consistent distinction can be made between the various disk structures, making it difficult to accurately assign a particular disc to a particular organism. Where other evidence exists, i.e. stem impressions, ornamentation, etc, it is possible to identify individual organisms or groups of organisms. But simple discs remain probematic. Being a disc does not make it a holdfast!<br /><br />It is entirely likely that <i>Aspidella</i> actually represents a group of diverse, not closely related, organisms - microbial, algal, fungal and metazoan - that produce discs and overlap each other to give <i>Aspidella</i> a large time range, but this time range is not for a single species or even genus.<br /><br />This boils down to the fact that <i>Aspidella</i> with stems or other ornamentation, and associated with other Ediacaran forms, can be considered a metazoan fossil. Other <i>Aspidella</i> with no other ornamentation, and not associated with Ediacaran forms, could be anything.<br /><br />The <i>Nimbia</i> find is in a similar situation. Do we have <i>Nimbia</i>? Yes. But here also, I think that the form <i>Nimbia</i>, like <i>Aspidella</i>, may hide a multitude of sins, or at the very least a number of different organisms. Except I think we have proof here that <i>Nimbia</i> is not an Ediacaran metazoan - or at least <b>this</b> <i>Nimbia</i> is not an Ediacaran metazoan.<br /><br />The specimens of <i>Nimbia</i> from the Kurgan Formation are found as positive epirelief, negative epirelief, and negative hyporelief. This does not happen for Ediacaran fossils, as discussed above. Since these <i>Nimbia</i> show a number of modes of preservation, and they all show the same structure regardless of mode of preservation, it is apparent that the form that produced it is rigid. It has to be if it produced the same shape whether on the top surface creating a positive or negative imprints, or on the bottom surface. The fossil is the same independent of preservational style, and so whatever is causing the fossil must therefore be rigid like a coin. That rigidity, and the various preservational styles, means that it cannot be a holdfast.<br /><br />It has been suggested that <i>Nimbia</i> represents microbial colonies. Hard, well agglutinated disk-shaped colonies would be tough enough to cause the impressions, and some have been known to develop a central nodule similar to that found in some <i>Nimbia</i>. This would explain the similar shape through different modes of preservation, and the large time range of the form.<br /><br />Finally, Ediacaran fossils are normally found as assemblages, with a number of different forms present. The Kurgan Formation specimens are of one main type, <i>Nimbia</i>, and a few <i>Aspidella</i>. Too restricted to be considered an assemblage (a random collection would be expected to uncover more than two forms if an assemblage was present). Even if this find represented an early stage in the evolution of metazoa, it would be expected that more than two forms would be present.<br /><br />So, discoial fossil with stem? - no. <i>Aspidella</i>? - yes, possibly, but that doesn't mean it's an Ediacaran or even metazoan. <i>Nimbia</i>? - yes, but probably not metazoan.<br /><br />In properly posing questions about their finds instead of making pronouncements, and suggesting a number of possible interpretations for their finds, Meert at al. have highlighted the important implication of their finds.<br /><blockquote><i>It is possible that our discovery of</i> Nimbia occlusa<i> and</i> Aspidella terranovica<i>(?) in sedimentary rocks during the early Cryogenian (N766 Ma) lends support the alternative hypotheses regarding these fossils and remove them from consideration as true metazoa</i>(<a href="http://dx.doi.org/10.1016/j.gr.2010.11.008">Meert <i>et al. 2010</i></a>.)</blockquote>I think they are right, they have provided evidence that the forms are not metazoan - or at least not "Ediacaran" (as in found amongst Ediacaran assemblages) - fossils, and that the simple disc-shaped forms found in the Proterozoic comprise a form group with contributions from a number of metazoan and non-metazoan sources.<br /><br /><br /><span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Gondwana+Research&rft_id=info%3Adoi%2F10.1016%2Fj.gr.2010.11.008&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Glaciation+and+%7E770Ma+Ediacara+%28%3F%29+Fossils+from+the+Lesser+Karatau+Microcontinent%2C+Kazakhstan&rft.issn=1342937X&rft.date=2010&rft.volume=&rft.issue=&rft.spage=&rft.epage=&rft.artnum=http%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS1342937X10002005&rft.au=Meert%2C+J.&rft.au=Gibsher%2C+A.&rft.au=Levashova%2C+N.&rft.au=Grice%2C+W.&rft.au=Kamenov%2C+G.&rft.au=Ryabinin%2C+A.&rfe_dat=bpr3.included=1;bpr3.tags=Geosciences%2CBiogeosciences%2C+Paleontology" style="font-size:85%;">Meert, J., Gibsher, A., Levashova, N., Grice, W., Kamenov, G., & Ryabinin, A. (2010). Glaciation and ~770Ma Ediacara (?) Fossils from the Lesser Karatau Microcontinent, Kazakhstan <span style="font-style: italic;">Gondwana Research</span> DOI: <a rev="review" href="http://dx.doi.org/10.1016/j.gr.2010.11.008">10.1016/j.gr.2010.11.008</a></span><br /><br /><br />Further reading on Ediacaran discs<br /><br /><span style="font-size:85%;">Gehling, J.G., Narbonne, G.M., and Anderson, M.M (2000) The first named ediacaran body fossil <i>Aspidella terranovica</i>. <i>Palaeontology</i>, 43: 427-456. <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.0031-0239.2000.00134.x/full">DOI: 10.1111/j.0031-0239.2000.00134.x</a></span><br /><br /><span style="font-size:85%;">MacGabhann, B.A. (2007) Discoidal fossils of the Ediacaran biota: a review of current understanding. <i>Geological Society, London, Special Publication</i>, 286: 297-313. <a href="http://sp.lyellcollection.org/cgi/content/abstract/286/1/297">DOI: 10.1144/SP286.21</a></span>Chris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.com7tag:blogger.com,1999:blog-5517176012861550589.post-83281897391434919562010-12-29T12:01:00.000+11:002010-12-29T12:01:00.119+11:00The Palaeontological Twelve Days of Christmas - Day 12Following on from the <a href="http://ediacaran.blogspot.com/2008/12/twelve-geology-days-of-christmas.html">Twelve Geology Days of Christmas</a>, this year we have a palaeontological version.<br /><blockquote><i>On the twelfth day of Christmas my true love sent to me, twelve <a href="http://www.abc.net.au/catalyst/stories/2929744.htm">insects in Australian amber</a> entombing,<br />eleven <a href="http://www.youtube.com/watch?v=RZcvbxlf9yk">ediacaran organisms</a> evolving,<br />ten <a href="http://www.guardian.co.uk/science/2009/sep/17/tiny-t-rex-fossil">tiny <i>T. rex</i></a> tyrranizing,<br />nine <a href="http://www.youtube.com/watch?v=m8lJKXn6MmQ&NR=1&feature=fvwp">Nigersaurus</a> nibbling,<br />eight <a href="http://www.youtube.com/watch?v=LYwwtrTH10A&feature=related">evolutionary digits</a> encroaching,<br />seven <a href="http://video.google.com/videoplay?docid=6799035742793330793#">seismosaurus</a> stomping,<br />six <a href="http://www.guardian.co.uk/science/2009/feb/04/snake-giant-fossil-titanoboa">snakes</a> aslithering,<br /><br />fiiiiive <a href="http://www.abc.net.au/catalyst/stories/2682334.htm">fossilllll fishhhhhhh</a>,<br /><br />four <a href="http://www.guardian.co.uk/science/video/2010/jan/05/first-tetrapods-walked-earth">fossil footprints</a> following,<br />three <a href="http://en.wikipedia.org/wiki/Tribrachidium">Tribrachidium</a> tripartiting<br />two <a href="http://www.youtube.com/watch?v=UDBB6ZnnB5g">trilobites</a> tasting,<br /><br />and a <a href="http://www.abc.net.au/catalyst/stories/2347748.htm">Cambrian Lagerstätte</a>.</i></blockquote>Chris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.com0tag:blogger.com,1999:blog-5517176012861550589.post-6015158594972256522010-12-28T12:01:00.000+11:002010-12-28T12:01:00.076+11:00The Palaeontological Twelve Days of Christmas - Day 11Following on from the <a href="http://ediacaran.blogspot.com/2008/12/twelve-geology-days-of-christmas.html">Twelve Geology Days of Christmas</a>, this year we have a palaeontological version.<br /><blockquote><i>On the eleventh day of Christmas my true love sent to me, eleven <a href="http://www.youtube.com/watch?v=RZcvbxlf9yk">ediacaran organisms</a> evolving,<br />ten <a href="http://www.guardian.co.uk/science/2009/sep/17/tiny-t-rex-fossil">tiny <i>T. rex</i></a> tyrranizing,<br />nine <a href="http://www.youtube.com/watch?v=m8lJKXn6MmQ&NR=1&feature=fvwp">Nigersaurus</a> nibbling,<br />eight <a href="http://www.youtube.com/watch?v=LYwwtrTH10A&feature=related">evolutionary digits</a> encroaching,<br />seven <a href="http://video.google.com/videoplay?docid=6799035742793330793#">seismosaurus</a> stomping,<br />six <a href="http://www.guardian.co.uk/science/2009/feb/04/snake-giant-fossil-titanoboa">snakes</a> aslithering,<br /><br />fiiiiive <a href="http://www.abc.net.au/catalyst/stories/2682334.htm">fossilllll fishhhhhhh</a>,<br /><br />four <a href="http://www.guardian.co.uk/science/video/2010/jan/05/first-tetrapods-walked-earth">fossil footprints</a> following,<br />three <a href="http://en.wikipedia.org/wiki/Tribrachidium">Tribrachidium</a> tripartiting<br />two <a href="http://www.youtube.com/watch?v=UDBB6ZnnB5g">trilobites</a> tasting,<br /><br />and a <a href="http://www.abc.net.au/catalyst/stories/2347748.htm">Cambrian Lagerstätte</a>.</i></blockquote>Chris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.com0tag:blogger.com,1999:blog-5517176012861550589.post-50627559014056080092010-12-27T12:01:00.000+11:002010-12-27T12:01:00.489+11:00The Palaeontological Twelve days of Christmas - Day 10Following on from the <a href="http://ediacaran.blogspot.com/2008/12/twelve-geology-days-of-christmas.html">Twelve Geology Days of Christmas</a>, this year we have a palaeontological version.<br /><blockquote><i>On the tenth day of Christmas my true love sent to me, ten <a href="http://www.guardian.co.uk/science/2009/sep/17/tiny-t-rex-fossil">tiny <i>T. rex</i></a> tyrranizing,<br />nine <a href="http://www.youtube.com/watch?v=m8lJKXn6MmQ&NR=1&feature=fvwp">Nigersaurus</a> nibbling,<br />eight <a href="http://www.youtube.com/watch?v=LYwwtrTH10A&feature=related">evolutionary digits</a> encroaching,<br />seven <a href="http://video.google.com/videoplay?docid=6799035742793330793#">seismosaurus</a> stomping,<br />six <a href="http://www.guardian.co.uk/science/2009/feb/04/snake-giant-fossil-titanoboa">snakes</a> aslithering,<br /><br />fiiiiive <a href="http://www.abc.net.au/catalyst/stories/2682334.htm">fossilllll fishhhhhhh</a>,<br /><br />four <a href="http://www.guardian.co.uk/science/video/2010/jan/05/first-tetrapods-walked-earth">fossil footprints</a> following,<br />three <a href="http://en.wikipedia.org/wiki/Tribrachidium">Tribrachidium</a> tripartiting<br />two <a href="http://www.youtube.com/watch?v=UDBB6ZnnB5g">trilobites</a> tasting,<br /><br />and a <a href="http://www.abc.net.au/catalyst/stories/2347748.htm">Cambrian Lagerstätte</a>.</i></blockquote>Chris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.com0tag:blogger.com,1999:blog-5517176012861550589.post-80054376055965560582010-12-26T12:01:00.000+11:002010-12-26T12:01:00.200+11:00The Palaeontological Twelve Days of Christmas - Day 9Following on from the <a href="http://ediacaran.blogspot.com/2008/12/twelve-geology-days-of-christmas.html">Twelve Geology Days of Christmas</a>, this year we have a palaeontological version.<br /><blockquote><i>On the ninth day of Christmas my true love sent to me, nine <a href="http://www.youtube.com/watch?v=m8lJKXn6MmQ&NR=1&feature=fvwp">Nigersaurus</a> nibbling,<br />eight <a href="http://www.youtube.com/watch?v=LYwwtrTH10A&feature=related">evolutionary digits</a> encroaching,<br />seven <a href="http://video.google.com/videoplay?docid=6799035742793330793#">seismosaurus</a> stomping,<br />six <a href="http://www.guardian.co.uk/science/2009/feb/04/snake-giant-fossil-titanoboa">snakes</a> aslithering,<br /><br />fiiiiive <a href="http://www.abc.net.au/catalyst/stories/2682334.htm">fossilllll fishhhhhhh</a>,<br /><br />four <a href="http://www.guardian.co.uk/science/video/2010/jan/05/first-tetrapods-walked-earth">fossil footprints</a> following,<br />three <a href="http://en.wikipedia.org/wiki/Tribrachidium">Tribrachidium</a> tripartiting<br />two <a href="http://www.youtube.com/watch?v=UDBB6ZnnB5g">trilobites</a> tasting,<br /><br />and a <a href="http://www.abc.net.au/catalyst/stories/2347748.htm">Cambrian Lagerstätte</a>.</i></blockquote>Chris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.com0tag:blogger.com,1999:blog-5517176012861550589.post-35297828217213020952010-12-25T12:01:00.000+11:002010-12-25T12:01:00.230+11:00The Palaeontological Twelve Days of Christmas - Day 8Following on from the <a href="http://ediacaran.blogspot.com/2008/12/twelve-geology-days-of-christmas.html">Twelve Geology Days of Christmas</a>, this year we have a palaeontological version.<br /><blockquote><i>On the eighth day of Christmas my true love sent to me, eight <a href="http://www.youtube.com/watch?v=LYwwtrTH10A&feature=related">evolutionary digits</a> encroaching,<br />seven <a href="http://video.google.com/videoplay?docid=6799035742793330793#">seismosaurus</a> stomping,<br />six <a href="http://www.guardian.co.uk/science/2009/feb/04/snake-giant-fossil-titanoboa">snakes</a> aslithering,<br /><br />fiiiiive <a href="http://www.abc.net.au/catalyst/stories/2682334.htm">fossilllll fishhhhhhh</a>,<br /><br />four <a href="http://www.guardian.co.uk/science/video/2010/jan/05/first-tetrapods-walked-earth">fossil footprints</a> following,<br />three <a href="http://en.wikipedia.org/wiki/Tribrachidium">Tribrachidium</a> tripartiting<br />two <a href="http://www.youtube.com/watch?v=UDBB6ZnnB5g">trilobites</a> tasting,<br /><br />and a <a href="http://www.abc.net.au/catalyst/stories/2347748.htm">Cambrian Lagerstätte</a>.</i></blockquote>Chris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.com0tag:blogger.com,1999:blog-5517176012861550589.post-51448894666094908412010-12-24T15:08:00.006+11:002010-12-24T15:32:41.057+11:00Why Dinosaurs Hate ChristmasBack by popular demand, and new and improved (well it has a new diagram . . .)<br /><br />Did you know that <a href="http://www.wearedinosaurs.com/">most</a> dinosaurs hate Christmas? It’s true, they do. And it’s not because they couldn’t get a handle on the present wrapping (or unwrapping for that matter) either. No, there is a very good reason why Dinosaurs hate Christmas.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhrjepN-SA6B14DqIOVr1uybMdhtnYb0yzRjjX1TOVxszm8Dpe70UMYn6fiA9zDSk7HYL4kt4BZJsonZ5smGHuHu5oHpJJhgpFAvVNcQKAoaKnMNzPPZ8JDevRHASuIqIG-PWGphssnuq7o/s1600-h/Dino1.jpg"><img style="margin: 0pt 0pt 10px 10px; float: right; cursor: pointer; width: 200px; height: 151px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhrjepN-SA6B14DqIOVr1uybMdhtnYb0yzRjjX1TOVxszm8Dpe70UMYn6fiA9zDSk7HYL4kt4BZJsonZ5smGHuHu5oHpJJhgpFAvVNcQKAoaKnMNzPPZ8JDevRHASuIqIG-PWGphssnuq7o/s200/Dino1.jpg" alt="" id="BLOGGER_PHOTO_ID_5283256571011312850" border="0" /></a>However, before explaining why dinosaurs hate Christmas, lets deal with some startling new information. Everyone is familiar with the standard explanation for the extinction of the dinosaurs. I've included a common representation of the event.<br /><br />However, startling 'evidence' has been presented which suggests another reason for what happened. The evidence is still officially hidden by the authorities, but one startling image has been smuggled out and is shown <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhGIqq0qduj8BSSDN4paDAw6qCNhs7sprhWphKX_Lhi29engK3J4ke9BaAfMH4LsUbAcLB3Riwzhv2VpE6Hxo9iIaxDmc78NbU5oy9pSQK2UDIJxXCJP8M1XcaoD1vhGXqlbDdPDQ0yxBXT/s200/Dino2.jpg">here</a> for the first time.<br /><br />It is claimed that it was one of Santa's early experiments on propulsion systems that went wrong and had to be ejected. Shocking as this image is, there are some who claim that it is a forgery and just another shot by those at war with Christmas.<br /><br />However, this is not the reason that dinosaurs hate Christmas. To understand that we need to know what dinosaurs are.<br /><br />In his classic 1842 publication on dinosaurs, Richard Owen named and defined the Dinosauria as: <br /><i>a group of exceedingly large, pachydermous reptiles from the Second Age . . . includes</i> Megalosaurus, Iguanodon <i>and</i> Hylaeosaurus.<br /><br />In 1997, <a href="http://www.geol.umd.edu/~tholtz/">Tom Holtz</a> provided a different definition: <br /><i>the last common ancestor of</i> Megalosaurus <i>and</i>Iguanodon<i> and all its descendants</i>. Using the same methodology, we can define dinosaurs as including the last common ancestor of the <a href="http://en.wikipedia.org/wiki/Herrerasauridae">Herrerasauidae</a> and the <a href="http://en.wikipedia.org/wiki/Hadrosaurid">Hadrosauridae</a>, and all their decendents.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3dlnR40xAfkOZjqFEleVNs8vFZFN3sqFBsN0QpWXHXaFdtA9MnG5XGusRnXOdvzAcvS297YIDzx8tvAivNg7KQ8JOanpcpCymqxrm_co3_6YsG7ybcOp29t2__VBcY95DblPVMu1xrDs8/s1600/Dinoclass.jpeg"><img style="display:block; margin:0px auto 10px; text-align:center;cursor:pointer; cursor:hand;width: 400px; height: 400px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3dlnR40xAfkOZjqFEleVNs8vFZFN3sqFBsN0QpWXHXaFdtA9MnG5XGusRnXOdvzAcvS297YIDzx8tvAivNg7KQ8JOanpcpCymqxrm_co3_6YsG7ybcOp29t2__VBcY95DblPVMu1xrDs8/s400/Dinoclass.jpeg" border="0" alt=""id="BLOGGER_PHOTO_ID_5554099469006981634" /></a><br />Anyhow, the thing about this definition is that, nestled between the the Herrerasaurs and the Hadrosaurs, are the Dromaeosaurs, and directly related to the Dromaeosaurs, and so one of the descendants mentioned above, is a little group called Aves!<br /><br />So with the mass slaughter of <s>birds</s> dinosaurs every Christmas, wouldn't you hate Christmas?<br /><br />If you insist in participating in this slaughter, at least make sure you cook your dinosaur correctly:<br /><br />1. If your dinosaur is frozen, fully thaw it.<br /><br />2. Don’t stuff the dinosaur. By the time the stuffing reaches a safe temperature, the meat is overcooked.<br /><br />3. Cover the dinosaur breast with ice while the rest of the dinosaur warms to room temperature. Don’t leave the dinosaur out for more than 3 hours. At this point, the breast will be about 4.5<sup>o</sup>C (40<sup>o</sup>F), while the rest of the meat will be at 15.5<sup>o</sup>C (60<sup>o</sup>F).<br /> <br />4. Put the dinosaur in the oven and cook according to your favorite recipe. <br /><br />5. With a meat thermometer, check temperature. Take out of the oven when legs reach 82<sup>o</sup>C(180<sup>o</sup>F) and breast hits between 68-71<sup>o</sup>C (155-160<sup>o</sup>F).<br /><br />Ho Ho Bleedin' Ho.Chris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.com2tag:blogger.com,1999:blog-5517176012861550589.post-33428820449651880272010-12-24T12:01:00.000+11:002010-12-24T12:01:00.545+11:00The Palaeontological Twelve Days of Christmas - Day 7Following on from the <a href="http://ediacaran.blogspot.com/2008/12/twelve-geology-days-of-christmas.html">Twelve Geology Days of Christmas</a>, this year we have a palaeontological version.<br /><blockquote><i>On the seventh day of Christmas my true love sent to me, seven <a href="http://video.google.com/videoplay?docid=6799035742793330793#">seismosaurus</a> stomping,<br />six <a href="http://www.guardian.co.uk/science/2009/feb/04/snake-giant-fossil-titanoboa">snakes</a> aslithering,<br /><br />fiiiiive <a href="http://www.abc.net.au/catalyst/stories/2682334.htm">fossilllll fishhhhhhh</a>,<br /><br />four <a href="http://www.guardian.co.uk/science/video/2010/jan/05/first-tetrapods-walked-earth">fossil footprints</a> following,<br />three <a href="http://en.wikipedia.org/wiki/Tribrachidium">Tribrachidium</a> tripartiting<br />two <a href="http://www.youtube.com/watch?v=UDBB6ZnnB5g">trilobites</a> tasting,<br /><br />and a <a href="http://www.abc.net.au/catalyst/stories/2347748.htm">Cambrian Lagerstätte</a>.</i></blockquote>Chris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.com0tag:blogger.com,1999:blog-5517176012861550589.post-13450605451393272982010-12-23T12:01:00.000+11:002010-12-23T12:01:00.177+11:00The Palaeontological Twelve Days of Christmas - Day 6Following on from the <a href="http://ediacaran.blogspot.com/2008/12/twelve-geology-days-of-christmas.html">Twelve Geology Days of Christmas</a>, this year we have a palaeontological version.<br /><blockquote><i>On the sixth day of Christmas my true love sent to me, six <a href="http://www.guardian.co.uk/science/2009/feb/04/snake-giant-fossil-titanoboa">snakes</a> aslithering,<br /><br />fiiiiive <a href="http://www.abc.net.au/catalyst/stories/2682334.htm">fossilllll fishhhhhhh</a>,<br /><br />four <a href="http://www.guardian.co.uk/science/video/2010/jan/05/first-tetrapods-walked-earth">fossil footprints</a> following,<br />three <a href="http://en.wikipedia.org/wiki/Tribrachidium">Tribrachidium</a> tripartiting<br />two <a href="http://www.youtube.com/watch?v=UDBB6ZnnB5g">trilobites</a> tasting,<br /><br />and a <a href="http://www.abc.net.au/catalyst/stories/2347748.htm">Cambrian Lagerstätte</a>.</i></blockquote>Chris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.com0tag:blogger.com,1999:blog-5517176012861550589.post-10974614230692934262010-12-22T12:01:00.000+11:002010-12-22T12:01:00.217+11:00The Palaeontological Twelve Days of Christmas - Day 5Following on from the <a href="http://ediacaran.blogspot.com/2008/12/twelve-geology-days-of-christmas.html">Twelve Geology Days of Christmas</a>, this year we have a palaeontological version.<br /><blockquote><i>On the fifth day of Christmas my true love sent to me, <br /><br />fiiiiive <a href="http://www.abc.net.au/catalyst/stories/2682334.htm">fossilllll fishhhhhhh</a>,<br /><br />four <a href="http://www.guardian.co.uk/science/video/2010/jan/05/first-tetrapods-walked-earth">fossil footprints</a> following,<br />three <a href="http://en.wikipedia.org/wiki/Tribrachidium">Tribrachidium</a> tripartiting<br />two <a href="http://www.youtube.com/watch?v=UDBB6ZnnB5g">trilobites</a> tasting,<br /><br />and a <a href="http://www.abc.net.au/catalyst/stories/2347748.htm">Cambrian Lagerstätte</a>.</i></blockquote>Chris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.com0tag:blogger.com,1999:blog-5517176012861550589.post-30750643923208496992010-12-21T12:01:00.001+11:002010-12-21T12:01:00.258+11:00The Palaeontological Twelve Days of Christmas - Day 4Following on from the <a href="http://ediacaran.blogspot.com/2008/12/twelve-geology-days-of-christmas.html">Twelve Geology Days of Christmas</a>, this year we have a palaeontological version.<br /><blockquote><i>On the fourth day of Christmas my true love sent to me, four <a href="http://www.guardian.co.uk/science/video/2010/jan/05/first-tetrapods-walked-earth">fossil footprints</a> following,<br />three <a href="http://en.wikipedia.org/wiki/Tribrachidium">Tribrachidium</a> tripartiting<br />two <a href="http://www.youtube.com/watch?v=UDBB6ZnnB5g">trilobites</a> tasting,<br /><br />and a <a href="http://www.abc.net.au/catalyst/stories/2347748.htm">Cambrian Lagerstätte</a>.</i></blockquote>Chris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.com0tag:blogger.com,1999:blog-5517176012861550589.post-30299051851416893222010-12-20T12:01:00.001+11:002010-12-20T16:03:20.768+11:00The Palaeontological Twelve Days of Christmas - Day 3Following on from the <a href="http://ediacaran.blogspot.com/2008/12/twelve-geology-days-of-christmas.html">Twelve Geology Days of Christmas</a>, this year we have a palaeontological version.<br /><blockquote><i>On the third day of Christmas my true love sent to me, three <a href="http://en.wikipedia.org/wiki/Tribrachidium">Tribrachidium</a> tripartiting,<br />two <a href="http://www.youtube.com/watch?v=UDBB6ZnnB5g">trilobites</a> tasting,<br /><br />and a <a href="http://www.abc.net.au/catalyst/stories/2347748.htm">Cambrian Lagerstätte</a>.</i></blockquote>Chris Nedinhttp://www.blogger.com/profile/06978886926715669724noreply@blogger.com3