Micrasterine spatangoids with:
Lower Cretaceous (Albian) to Recent; worldwide.
Echinoids that possess a subanal fasciole fall into two distinct groups. The Micrasteridae are distinguished from the remainder by their ethmophract apical disc, their alternate episternal plates and the specific pathway followed by the subanal fasciole. They are the more primitive and appear earlier in the fossil record.