Ankylosphenodon pachyostosus (Reynoso 2000) Early Cretaceous (Albian) 55 cm snout-vent length was a basal rhynchocephalian derived from Gephyrosaurus and a sister to the aquatic Palaeopleurosaurus.
Distinct from Gephyrosaurus, Ankylosphenodon had a low, wide skull and robust, elongate vertebrae and relatively short limbs. A single premaxillary tusk was present, as in Palaeopleurosaurus, convergent with the deep premaxilla/tooth found in rhynchosaurs like Rhynchosaurus. The pectoral girdle was tiny with a much smaller scapula. |
