A new cryptodont dicynodont (Therapsida, Anomodontia) from the Lopingian Usili Formation, Ruhuhu Basin, Tanzania

Cryptodontia is a diverse and widespread group of Permian dicynodonts, although its exact membership has been a subject of uncertainty in recent phylogenetic analyses. Cryptodont fossils were first reported from the Lopingian Usili Formation (Ruhuhu Basin, Tanzania) in 1932, with the current composition of the Usili cryptodont assemblage emerging from taxonomic revisions in the mid-2000s. Here we describe a new cryptodont, <i>Mdomowabata trilobops</i>, gen. et sp. nov., from the Usili Formation. Diagnostic characters of <i>M. trilobops</i> include: transversely expanded caniniform process of the maxilla that has a bluntly rounded ventral tip; paired nasal bosses; hatchet-shaped exposure of the postfrontal on the dorsal surface of the skull; parietals that are widely exposed dorsally; intertemporal portion of the postorbital that is oriented vertically with a concave lateral surface; triangular exposure of the postparietal on the skull roof; low, close-set anterior median palatal ridges; large palatine pad with a rugose posterior section and a smoother anterior section that is flush with the premaxillary secondary palate; transversely broad and anteroposteriorly short symphyseal region of the mandible; and prominent, round muscle scar anterior to the external mandibular fenestra. The plow-shaped snout and evidence of increased facial sensitivity suggest that <i>Mdomowabata</i> used its snout to interact with the substrate. A phylogenetic analysis recovers <i>M. trilobops</i> within a monophyletic Cryptodontia, on the stem leading to a clade comprising Oudenodontidae and Rhachiocephalidae. However, persistent problems in recovering stable relationships suggest that a critical reassessment of the character data underlying current dicynodont phylogenies is needed.