bar. Limbs Dinocephalosaurus had relatively large legs terminating in flipper-like feet. The forelimbs and hindlimbs are roughly the same length, unlike Tanystropheus where the forelimbs were much smaller. Whereas most protorosaurs, such as Tanystropheus, Macrocnemus, and Langobardisaurus, had relatively ossified limbs adapted for terrestrial life, the stout limbs of Dinocephalosaurus were poorly ossified and resembled those of nothosaurs. Out of the carpal bones, only six were ossified; similarly, only three of the tarsal bones were ossified. Additionally, the astragalus and calcaneum also did not articulate with each other in the ankle, instead forming simple and rounded ossifications. Another adaptation to aquatic life was the loss of an opening known as the thyroid fenestra in the pelvis due to the rounded pelvic bones, which was also present in Fuyuansaurus. These traits were probably neotenic, which similarly characterizes traits found in many other aquatic tetrapods. While Tanystropheus was likely also neotenic, it did not approach Dinocephalosaurus in the extremity of this condition. Several other peculiar traits were present in the feet of Dinocephalosaurus. Unlike Tanystropheus and most other protorosaurs, the fifth metatarsal of Dinocephalosaurus was simple and straight instead of hooked. Tanystropheus had a fifth metatarsal which was mildly thickened at the top end, and it additionally possessed a long phalanx on the fifth digit that acted not unlike another metatarsal. On the third digit of the foot of Dinocephalosaurus, there were four phalanges, but none of them appear to have been the terminal claw. This suggests that Dinocephalosaurus had a higher-than-average count of at least five phalanges in the third digit. Classification Dinocephalosaurus was considered to be a member of the Protorosauria, a group of ubiquitous and diverse Permo-Triassic reptiles. This assignment was based upon characteristics including the low and narrow skull with a short and narrow postorbital region; the long nasal bone relative to the frontal bone; the reduced backward projection of the jugal; the presence of more than seven neck vertebrae, with centra (bodies) longer than those of the trunk vertebrae; the low neural spines of the neck vertebrae; the long neck ribs; the lack of intercentra articulating with the centra of the trunk vertebrae; and the absence of an entepicondylar foramen on the humerus. These characteristics were shared with Tanystropheus, Macrocnemus, and other protorosaurs. Protorosaurs were formerly considered to be the ancestors of lizards, but phylogenetic analysis has subsequently verified that they were in fact non-archosaur archosauromorphs. As