Ontogeny and cranial morphology of the basal carnivorous dinocephalian, Anteosaurus magnificus from the Tapinocephalus Assemblage Zone of the South African Karoo{����

KRUGER, A.; RUBIDGE, B.S.; ABDALA, F.

Johannesburgo

Conferencia; 18th Biennial Conference of the Palaeontological Society of Southern Africad; 2014

Palaeontological Society of southern Africa

Anteosaurs (Therapsida: Dinocephalia: Anteosauria) were the dominant terrestrial predators during the late Middle Permian period and became extinct at the close of the Tapinocephalus Assemblage Zone. Only two genera of anteosaurs, Australosyodon and Anteosaurus, are recognized from the Karoo rocks of South Africa. A newly discovered small anteosaurid skull from the Abrahamskraal Formation is fully described. Because of its relatively large orbits, the unfused nature of its sutures, and the lack of replacement teeth in the dental alveoli, the specimen is considered to be a juvenile Anteosaurus magnificus. A full computer-aided 3-D reconstruction of the skull enabled cranial measurements to be taken for an allometric analysis which included 23 measurements and 11 specimens. Positive allometry was found for four of the measurements suggesting fast growing in the temporal region, and a significant difference in the development of the postorbital bar and suborbital bar between juveniles and adults. Phylogenetic research shows that the Russian anteosaurids are forerunners to Anteosaurus, and because the juvenile Anteosaurus manifests many features of both Syodon and Titanophoneus, it is suggested that ontogenetic growth of Anteosaurus follows Haeckel?s Law.