Article: New material of Youngina: evidence of juvenile aggregation in Permian diapsid reptiles

An unusual specimen of Youngina is described from a new locality in the Karoo Basin of South Africa. The locality is in the Tropidostoma Assemblage Zone (equivalent to the former Lower Cistecephalus Zone), making the specimen the oldest recorded example of this genus. It comprises an association of five immature skeletons which are fully articulated and thus provide the first clear indication of body proportions in Youngina. In addition, the material yields new information on the pectoral girdle, pelvis and foot. It is clear that Youngina, unlike many of its known relatives, was an agile, fully terrestrial animal. This conclusion is reinforced by the preservation of the young skeletons in positions which suggest group denning behaviour in response to adverse climatic conditions.