Tanysauria (meaning "long lizards") is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

long-necked

archosauromorph Archosauromorpha (Greek for "ruling lizard forms") is a clade of diapsid reptiles containing all reptiles more closely related to archosaurs (such as crocodilians and dinosaurs, including birds) than to lepidosaurs (such as tuataras, lizards, a ...

reptiles from the

Triassic The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is t ...

period of Europe, Asia, North America, and South America. It comprises the families

Tanystropheidae Tanystropheidae is an extinct family (biology), family of archosauromorph reptiles that lived throughout the Triassic Period, often considered to be "protorosaurs". They are characterized by their long, stiff necks formed from elongated cervical ...

and Trachelosauridae (found by the authors to be coextensive with

Dinocephalosauridae Trachelosauridae (also known as Dinocephalosauridae) is an extinct clade of archosauromorph reptiles that lived throughout the Triassic period. Like their close relatives the tanystropheids, they were "Protorosauria, protorosaur"-Evolutionary gra ...

, and a senior synonym of the latter). Within the Archosauromorpha, Tanysauria represents the

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

to the Crocopoda. It contains many of the species formerly placed in "

Protorosauria 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 t ...

", which is now thought to be a

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

group.

Definition

The clade Tanysauria was described by Stephan Spiekman and co-authors in 2024. Its name comes from the

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

τᾰνυ 'tany''meaning "long" and σαῦρος 'sauros''meaning "lizard," which refers to the long necks and, in some cases, bodies of tanysaurians. According to the

phylogenetic definition Phylogenetic nomenclature is a method of nomenclature for taxa in biology that uses phylogenetic definitions for taxon names as explained below. This contrasts with the traditional method, by which taxon names are defined by a ''type'', which can ...

given by Spiekman et al., the clade Tanysauria includes all taxa that are more closely related to ''

Tanystropheus longobardicus ''Tanystropheus'' (~ 'long' + 'hinged') is an extinct genus of archosauromorph reptile which lived during the Triassic period, Triassic Period in Europe, Asia, and North America. It is recognisable by its extremely elongated neck, longer than t ...

'', '' Dinocephalosaurus orientalis'', and '' Trachelosaurus fischeri'' than to ''

Protorosaurus speneri ''Protorosaurus'' (from , 'earlier' and , 'lizard') is an extinct genus of reptile. Members of the genus lived during the late Permian period in what is now Germany and Great Britain. Once believed to have been an ancestor to lizards, ''Protoro ...

'', '' Prolacerta broomi'', ''

Mesosuchus browni ''Mesosuchus'' ("middle crocodile") is an extinct genus of basal rhynchosaur from early Middle Triassic (early Anisian stage) deposits of Eastern Cape, South Africa. It is known from the holotype SAM 5882, a partial skeleton, and from the para ...

'', ''

Azendohsaurus madagaskarensis ''Azendohsaurus'' is an extinct genus of herbivorous archosauromorph reptile from roughly the late Middle to early Late Triassic Period of Morocco and Madagascar. The type species, ''Azendohsaurus laaroussii'', was described and named by Jean-Mic ...

'', or ''

Proterosuchus fergusi ''Proterosuchus'' is an extinct genus of archosauriform reptiles that lived during the Early Triassic. It contains three valid species: the type species ''P. fergusi'' and the referred species ''P. alexanderi'' and ''P. goweri''. All three spec ...

''.

Classification

In their 2024 redescription of '' Trachelosaurus'', Spiekman and colleagues named Tanysauria as a new clade containing the Tanystropheidae and Trachelosauridae (a

senior synonym In taxonomy, the scientific classification of living organisms, a synonym is an alternative scientific name for the accepted scientific name of a taxon. The botanical and zoological codes of nomenclature treat the concept of synonymy differently. ...

of Dinocephalosauridae). This clade is the sister taxon to the Crocopoda. The results of their phylogenetic analyses are shown in the

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

below:

References

{{Taxonbar, from=Q124862562 Archosauromorpha Triassic reptiles Triassic first appearances Triassic extinctions