Sunday, March 8, 2009

Palaeoporn 11



A slightly different Palaeoporn this time, as there's a bit of a theme this week, on preservation. A bit later I'll be discussing how to fossilise muscle tissue. This, and other specimens helped in coming up with the process.

This is a fragment of an Anomalocaris appendage from the Cambrian Emu Bay Shale. The interesting thing is the preservation. The outer layer preserves the impression of the appendage, together with segment boundaries. Inside, is a layer of fibrous calcite crystals. The specimen has been re-crystallised after a metamorphic event which included overthrusting. The crystals are, in fact aligned to the stress field, as they 'lean' towards the north - the thrust direction was south to north.

1 comment:

  1. Been good to see you on the blog. But, for us non-paleo types, could you include some arrows as to where the fragments are?

    I confess that in the DC Howlerfest, where you guided a superb tour of the Smithsonian, when you were pointing to things and saying any 4 year old could tell ..., I wasn't faring as well as your 4 year old.

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