Neodiapsida

Neodiapsids Temporal range: Cisuralian–Present, 289–0 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Skull of Orovenator, the earliest known neodiapsid
Skeleton of Megalancosaurus, a drepanosaur
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Diapsida
Clade:	Neodiapsida Benton, 1985
Subgroups and genera
†Acallosuchus †Claudiosaurus †Elachistosuchus †Kenyasaurus †Kudnu †Lanthanolania †Maiothisavros †Longisquama †Orovenator †Palacrodon †Palaeagama †Protoavis (dubious) †Saurosternon †Younginiformes (possibly paraphyletic) †Tangasauridae †Younginidae †Avicephala (possibly non-monophyletic) †Drepanosauromorpha †Weigeltisauridae †Longisquama? †Ichthyosauromorpha †Sauropterygia †Thalattosauria †Choristodera Sauria

Neodiapsida is a clade, or major branch, of the reptilian family tree, typically defined as including all diapsids apart from some early primitive types known as the araeoscelidians. Modern reptiles and birds belong to the neodiapsid subclade Sauria.

The oldest known neodiapsids are Orovenator and Maiothisavros from the Early Permian of North America, around 290 million years old.^[1][2]

Basal-non saurian neodiaspids were ancestrally lizard-like, but basal non-saurian neodiapsids include aquatic/amphibious taxa (Claudiosaurus and some tangasaurids)^[3] the gliding lizard-like Weigeltisauridae,^[4] as well as the Triassic chameleon-like drepanosaurs.^[5] The position of the highly derived Mesozoic marine reptile groups Thalattosauria, Ichthyosauromorpha and Sauropterygia within Neodiapsida is uncertain, and they may lie within Sauria.^[6]

Classification

The clade Neodiapsida was given a phylogenetic definition by Laurin in 1991. He defined it as the branch-based clade containing all animals more closely related to "Younginiformes" (later, more specifically, emended to Youngina capensis) than to Petrolacosaurus.^[7] The cladogram presented here illustrates the "family tree" of reptiles, and follows a simplified version of the relationships found by M.S. Lee, in 2013.^[8] All genetic studies have supported the hypothesis that turtles are diapsid reptiles; some have placed turtles within archosauromorpha,^[8][9] or, more commonly, as a sister group to extant archosaurs.^{[10][11][12][13]} though a few have recovered turtles as lepidosauromorphs instead.^[14] The cladogram of Lee (2013) below used a combination of genetic (molecular) and fossil (morphological) data to obtain its results.^[8]

Diapsida	†Araeoscelidia Neodiapsida †Claudiosaurus †Younginiformes Sauria Lepidosauromorpha †Kuehneosauridae Lepidosauria Rhynchocephalia (tuatara and their extinct relatives) Squamata (lizards and snakes) Archosauromorpha †Choristodera †Prolacertiformes †Rhynchosauria †Trilophosaurus Archosauriformes (crocodiles, birds, and their extinct relatives)

This second cladogram is based on the 2017 study by Pritchard and Nesbitt.^[15]

Neodiapsida	†Orovenator †Drepanosauromorpha †Weigeltisauridae †Claudiosaurus †Tangasauridae (Hovasaurus, Thadeosaurus, Acerosodontosaurus) †Younginidae (Youngina+unnamed species) Sauria Lepidosauria Archosauromorpha †Protorosaurus †Tanystropheidae †Rhynchosauria †Allokotosauria †Prolacerta Archosauriformes

The following cladogram was found by Simões et al. (2022): ^[16]

Neoreptilia

†Procolophonomorpha Neodiapsida †Younginiformes †Eunotosaurus †Weigeltisauridae Sauria Lepidosauromorpha Rhynchocephalia (tuatara and their extinct relatives) Squamata (lizards and snakes) Archelosauria Pantestudines (turtles and extinct relatives) Archosauromorpha †Ichthyosauromorpha †Sauropterygia †Thalattosauria †Protorosauria †Protorosauridae †Tanystropheidae †Drepanosauromorpha †Kuehneosauridae †Allokotosauria †Rhynchosauria Archosauriformes (crocodiles, birds, and their extinct relatives)

References

• Callaway, J.M. (1997), Ichthyosauria: Introduction, in JM Callaway & EL Nicholls (eds.), Ancient Marine Reptiles. Academic Press, pp. 3–16.
• Laurin, Michel and Gauthier, Jacques A. (2000) Autapomorphies of Diapsid Clades

External links

• Eureptilia: Neodiapsida
• Neodiapsida cladogram

This page was last edited on 12 April 2024, at 13:01