Hemipatagus carolinensis 1.JPG
Hemipatagus carolinensis sea urchin
Eastern North Carolina
Oligocene (33.9 - 23 million years ago)
The echinoid genus Hemipatagus is a poorly understood fossil spatangoid taxon that is now usually treated as a subjective synonym of the extant genus Maretia, but was originally subject to considerable dispute within the scientific community. Restudy of the species attributed to Hemipatagus and a range of presumably related spatangoids including Lovenia and Maretia has been carried out to solve the problem of its relationships. Cladistic analysis shows that Hemipatagus is not close to Maretia, but is closely related to Lovenia and should be placed in the Loveniidae, which is here confirmed as a monophyletic group. Characters of the adapical tuberculation suggest that in Hemipatagus an internal fasciole is present in early ontogeny, but lost in the adults. A clade comprising the genera Eurypatagus, Paramaretia and Platybrissus, and here named Eurypataginae, appears in all resulting trees as sister group to Maretia.