Abrictosaurus consors

Description. The holotypic skeleton of Abrictosaurus consors (NHMUK RU B 54), which is preserved for the most part in natural articulation, is the most complete specimen of a heterodontosaurid with the single exception of a nearly complete skeleton of Heterodontosaurus tucki (SAM-PK-K 1332; Santa Luca et al. 1976; Santa Luca 1980). The following brief description of the holotypic specimen clarifies aspects of the morphology critical to the taxonomy and phylogenetic relationships of this important heterodontosaurid. The skull and skeleton require further preparation before a more detailed description is possible. The skull and femur of the single known specimen of Abrictosaurus consors are approximately 71 % and 68 % of the length of the skull and femur in Heterodontosaurus tucki (SAM-PK-K 1332; Table 3), respectively. This suggests that Abrictosaurus consors probably grew to a comparable adult body size. Preserved in two pieces, the skull is transversely compressed and better exposed in left lateral view (Fig. 31). Much of the dorsal skull roof, braincase, and posterior end of the lower jaws are broken away. The postcranial skeleton is preserved on separate blocks, one preserving an articulated right forelimb (Fig. 36) and the other the ilia, an ischium, sacrum and left hindlimb (Fig. 37). The phalanges of the right manus cross onto the skull block and are partially exposed near the scleral ring in the left orbit (Fig. 31).