Scincosaurus crassus (Fric 1876). Westphalian 310 mya, was a basal nectridean. Derived from a sister to Sauropleura and Kirktonecta, terrestrial Scincosaurus phylogenetically preceded aquatic Pantylus and Stegostretus.
Distinct from Kirktonecta, the skull of Scincosaurus had a smaller orbit and smaller naris set further back from the snout tip. The skull was relatively smaller. The cheek descended past the jawline.
The presacral count was down to 24, as in Pantylus, and far fewer than the 40 in Microbrachis. The neural spines and vertebrae expanded to eliminate any space between each one and its neighbor. The cervical ribs were not so robust and posteriorly oriented. The tail was longer and without chevrons.
The clavicles and interclavicle were robust ventrally, extending further anteriorly. The cleithrum was longer. The scapulocoracoid was well ossified. The limbs were slightly larger. The pelvis was more robust. |
