The Palaeontological Twelve Days of Christmas - Day 12

Following on from the Twelve Geology Days of Christmas, this year we have a palaeontological version.

On the twelfth day of Christmas my true love sent to me, twelve insects in Australian amber entombing,
eleven ediacaran organisms evolving,
ten tiny T. rex tyrranizing,
nine Nigersaurus nibbling,
eight evolutionary digits encroaching,
seven seismosaurus stomping,
six snakes aslithering,

fiiiiive fossilllll fishhhhhhh,

four fossil footprints following,
three Tribrachidium tripartiting
two trilobites tasting,

and a Cambrian Lagerstätte.