Extinct family of reptiles
Younginidae is an extinct family of diapsid reptiles from the Late Permian and Early Triassic . In a phylogenetic context, younginids are near the base of the clade Neodiapsida . Younginidae includes the species Youngina capensis from the Late Permian of South Africa and Thadeosaurus colcanapi from the Late Permian and Early Triassic of Madagascar . Heleosuchus griesbachi from the Late Permian of South Africa may also be a member of the family.
Younginidae was traditionally assigned to Eosuchia , an order containing an assemblage of basal diapsids now thought to represent an evolutionary grade rather than a true clade. In 1945 paleontologist Alfred Romer reclassified Younginidae within a new group, Younginiformes , grouping it with the families Tangasauridae and Prolacertidae . Romer considered Younginidae to include many genera that are no longer classified as younginids: Paliguana , Palaegama , and Saurosternon are now considered basal lepidosauromorphs , Galesphyrus and Heleosuchus are diapsids of uncertain affinities (incertae sedis ), Heleophilus is now a millerettid , and Heleosaurus is now thought to be a varanopid synapsid.[1] [2] Like Eosuchia, Younginiformes is no longer considered valid; for example, the phylogenetic analysis of Reisz et al. place younginids close to Sauria , the clade including the still-living archosauromorph and lepidosauromorph reptiles, while the younginiform family Tangasauridae takes a more basal position in Neodiapsida.[3] Below is a cladogram from that analysis:[3]
References
See also
Possible sauropsids Other taxa