Description
Ptychagnostus praecurrens
Middle Cambrian
Burgess Shale, Stephens Formation
Field British Columbia, Canada
Ptychagnostus is especially important to Cambrian paleontology because these trilobites evolved rapidly and are widely used for correlating Middle Cambrian rocks. This tiny specimen preserves an excellent example of one of the early arthropods that inhabited Cambrian seas more than 500 million years ago.
Agnostids have been puzzling for over a century. Recent research using Burgess Shale specimens suggest that agnostids are a close sister group to trilobites and not trilobites themselves!
Very fine 8mm agnostid.
See: Burgess Shale fossils shed light on the agnostid problem (PDF – opens in new tab)
