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Younginidae
Extinct family of reptiles From Wikipedia, the free encyclopedia
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Younginidae is an extinct family of diapsid reptiles from the Late Permian. In a phylogenetic context, younginids are near the base of the clade Neodiapsida. The only species definitively a member of the Younginidae is Youngina capensis from the Late Permian of South Africa. Several genera have historically been assigned to this family, though more recent phylogenetic analyses have supported relationships with other clades. Heleosuchus griesbachi from the Late Permian of South Africa may also be a member of the family.[1]
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.[2][3] 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.[4] Below is a cladogram from that analysis:[4]
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