Circulocrania

Circulocrania Temporal range: Late Arenig[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Trilobita
Genus:	Circulocrania

Circulocrania is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived during the later part of the Arenig stage of the Ordovician Period^[1], approximately 478 to 471 million years ago.

References

1. ^ ^{a b} Sepkoski, Jack (2002). "A compendium of fossil marine animal genera (Trilobita entry)". Bulletins of American Paleontology 364: p.560. http://strata.ummp.lsa.umich.edu/jack/showgenera.php?taxon=307&rank=class. Retrieved 2008-01-12.