Protorosauria

Protorosaurs Temporal range: Latest Middle Permian - Late Triassic, 260–201.3 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Fossil specimen of Protorosaurus speneri, Teyler's Museum
Skeletal reconstructions of various members of Tanysauria, including Trachelosaurus fischeri, Dinocephalosaurus orientalis, Tanystropheus hydroides, and Tanystropheus longobardicus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Archosauromorpha
Order:	†Protorosauria Huxley, 1871
Subtaxa
†Czatkowiella †Exilisuchus? †Jesairosaurus †Malutinisuchus †Mecistotrachelos? †Megacnemus †Microcnemus †Protorosaurus †Rhombopholis † Tanysauria † Sharovipterygidae? †Trachelosauridae †Tanystropheidae

Protorosauria is an extinct, likely paraphyletic group of basal archosauromorph reptiles from the latest Middle Permian (Capitanian stage) to the end of the Late Triassic (Rhaetian stage) of Asia, Europe and North America. It was named by the English anatomist and paleontologist Thomas Henry Huxley in 1871 as an order, originally to solely contain Protorosaurus. Other names which were once considered equivalent to Protorosauria include Prolacertiformes and Prolacertilia.^[1]

Protorosaurs are distinguished by their long necks formed by elongated cervical vertebrae, which have ribs that extend backward to the vertebrae behind them. Protorosaurs also have a gap between the quadrate bones and the jugal bones in the back of the skull near the jaw joint, making their skulls resemble those of lizards.^[1] While previously thought to be monophyletic, the group is now thought to consist of various groups of basal archosauromorph reptiles that lie outside Crocopoda,^[2] though some recent studies have recovered the group as monophyletic.^[3] A number of members of Protosauria have been found to belong to a monophyletic group (though not including Protorosaurus) which was named Tanysauria in 2024.^[4]