Plateosauridae

Plateosauridae is a family of sauropodomorph dinosaurs from the Late Triassic, known from fossils discovered in Europe, Greenland, Africa, and Asia. Today, the family is limited to the genera Plateosaurus, Yimenosaurus, Euskelosaurus, and Issi. Some earlier classifications included other genera, but Sellosaurus was reassigned as a species of Plateosaurus (as P. gracilis) in a 2003 study, and Gresslyosaurus is sometimes treated as a separate genus or as a synonym of Plateosaurus.

The family was first named by Othniel Charles Marsh in 1895. It has been defined in several ways: in 1998, as all animals more closely related to Plateosaurus engelhardti than to Massospondylus carinatus; in 2004, as all animals more closely related to P. engelhardti than to either M. carinatus or Yunnanosaurus huangi; and in 2007, as all animals more closely related to P. engelhardti than to Diplodocus longus. Recent cladistic analyses suggest that the group Prosauropoda, named in 1920 and defined in 1998 as all animals more closely related to P. engelhardti than to Saltasaurus loricatus, contains the same taxa as Plateosauridae, making the two names synonyms.

A 2017 study by Baron, Norman, and Barrett recovered Plateosauridae as a monophyletic group within the clade Plateosauria, with Massopoda as its sister group. A 2021 study by Beccari et al. describing Issi saaneq found it to be the sister taxon of Plateosaurus, and also placed Macrocollum and Unaysaurus within Plateosauridae.