Wikipedia
Tapinocephalidae was an advanced family of tapinocephalians.It is defined as the clade containing Ulemosaurus, Tapinocaninus, and the Tapinocephalinae They are known from both Russia and South Africa. In all probability, the Tapinocephalidae had a worldwide (Pangean) distribution.They flourished briefly during the Wordian and Capitanian ages, radiating into several lineages, existing simultaneously, and differing mainly in details of the skull and, to an even lesser degree, the skeleton. It is not clear how such similar animals could each find their own ecological niche, but such was obviously the case. There is a parallel here with the hadrosaur and ceratopsian dinosaurs of the Late Cretaceous. The cause of their abrupt extinction is not clear, since other smaller animals, and even the pareiasaurs, were not affected. Quite probably, like the extinction of the late Pleistocene megafauna, a number of factors were involved.