4.10 Procolophon sp.
This is a cast of the skull, lower jaw and shoulder girdle of a procolophonid. This group includes fairly small amniotes from the Permian and Triassic. Procolophonids and pareiasaurs (see Bradysaurus and Scutosaurus) are thought to be closely related to each other according to several recent cladistic analyses. Together with a few other groups of early amniotes procolophonids and pareiasaurs are regarded as members of a clade called the parareptiles. Turtles may have evolved from parareptile ancestors: some authors have suggested the procolophonids, others have proposed the pareiasaurs (but these hypotheses remain controversial).
Procolophonids can be recognised by several features in the skull. Note: the skull is subtriangular in dorsal view, and is somewhat dorsoventrally flattened, the orbit is emarginated along its back edge (what might this feature have been for?), in some forms there are various spikes of bone on the head (see Hypsognathus): what function might these have served?
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