Belebey vegrandis (Ivakhnenko 1973) Cisuralian, middle Permian ~284 mya, 4 cm skull length, was a sister to Bolosaurus and Phonodus. This clade nested with the diadectids and may represent yet another instance of phylogenetic miniaturization.
Belebey had orbits higher on the skull and a very low lateral temporal fenestra formed by deep embayment of the jugal and apparent loss of the quadratojugal process. The "brows" anterior to the orbits were much wider. The teeth were uniquely wide and angled in the jaws. The pineal foramen was much larger. There was no posterior embayment of the skull. The occipital plane leanded slightly anteriorly. The dentary was ventrally concave. The posterior dentary rose to a high coronoid process as in Bolosaurus. |
