Trachelosauridae Abel, 1919

Spiekman, Stephan N. F., Ezcurra, Martín D., Rytel, Adam, Wang, Wei, Mujal, Eudald, Buchwitz, Michael & Schoch, Rainer R., 2024, A redescription of TraCheloSaUrUS fiSCheri from the Buntsandstein (Middle Triassic) of Bernburg, Germany: the first European DinoCephaloSaUrUS-like marine reptile and its systematic implications for long-necked early, Swiss Journal of Palaeontology (10) 143 (1), pp. 1-33 : 8

Trachelosauridae Abel, 1919 1 (= Dinocephalosauridae Spiekman, Fraser and Scheyer, 2021)

Phylocode registration number. Trachelosauridae is identified in the international clade names repository as registration number 1028.

Phylogenetic definition. The definition of Trachelosauridae is modified from the definition for Dinocephalosauridae ( Spiekman et al., 2021b) as follows: the most inclusive clade containing Trachelosaurus fischeri Broili, 1918 and Dinocephalosaurus orientalis Li, 2003 but not Tanystropheus longobardicus ( Bassani, 1886) , Macrocnemus bassanii Nopcsa, 1931 , Protorosaurus speneri von Meyer, 1832 , or Prolacerta broomi Parrington, 1935 . This is a maximum clade definition.

Reference phylogeny. Phylogenetic hypotheses recovered in this paper.

Composition. The composition is based on our reference phylogenies. Trachelosauridae includes the following nominal species: Dinocephalosaurus orientalis , Trachelosaurus fischeri, Austronaga minuta, Pectodens zhenyuensis , and ambiguously Gracilicollum latens, and Fuyuansaurus acutirostris .

Diagnosis. Trachelosauridae is a clade that is defined among other archosauromorphs by possessing the following unique combination of character states: external naris positioned far from the anterior end of the premaxilla, resulting in an anteroposteriorly deep base of the prenarial process; jugal without posterior process; cervical column composed of ten or more vertebrae (also present in some deeply nested tanystropheids); axis with postzygapophysis confluent with and not protruding posteriorly from the base of the neural spine in lateral view (also present in Tanystropheus spp. and Amotosaurus rotfeldensis ); mid-dorsal vertebrae with very wide and ‘wing-like’ transverse processes; presence of holocephalous anterior dorsal ribs (also present in some tanystropheids); metatarsal V without a hook-shaped proximal end.