''Wumengosaurus'' is an extinct aquatic reptile from the

Middle Triassic In the geologic timescale, the Middle Triassic is the second of three epochs of the Triassic period or the middle of three series in which the Triassic system is divided in chronostratigraphy. The Middle Triassic spans the time between Ma and ...

(late

Anisian In the geologic timescale, the Anisian is the lower stage or earliest age of the Middle Triassic series or epoch and lasted from million years ago until million years ago. The Anisian Age succeeds the Olenekian Age (part of the Lower Triassic ...

stage)

Guanling Formation The Guanling Formation is a Middle Triassic (Anisian or Pelsonian in the regional chronostratigraphy) geologic formation in southwestern China. Description The formation encompasses two members. The first member is primarily calcareous muds ...

Guizhou Guizhou (; formerly Kweichow) is a landlocked province in the southwest region of the People's Republic of China. Its capital and largest city is Guiyang, in the center of the province. Guizhou borders the autonomous region of Guangxi to the ...

, southwestern China. It was originally described as a basal eosauropterygian and usually is recovered as such by

phylogenetic analyses In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

, although one phylogeny has placed it as the sister taxon to

Ichthyosauromorpha The Ichthyosauromorpha are an extinct clade of marine reptiles consisting of the Ichthyosauriformes and the Hupehsuchia, living during the Mesozoic. The node clade Ichthyosauromorpha was first defined by Ryosuke Motani ''et al.'' in 2014 as t ...

while refraining from a formal re-positioning. It was a relatively small reptile, measuring in total body length and weighing . In 2021, Qin ''et al''. described an additional specimen from Guizhou ( Panzhou District) as a new species of ''Wumengosaurus'', ''W. rotundicarpus''.

Classification

In the 2023

description Description is the pattern of narrative development that aims to make vivid a place, object, character, or group. Description is one of four rhetorical modes (also known as ''modes of discourse''), along with exposition, argumentation, and narra ...

of ''

Luopingosaurus ''Luopingosaurus'' (meaning "Luoping lizard") is an extinct genus of pachypleurosaurid sauropterygian from the Middle Triassic Guanling Formation of Yunnan Province, China. The genus contains a single species, ''L. imparilis'', known from a wel ...

'', Xu ''et al''. recovered ''Wumengosaurus'' as a derived pachypleurosaurid, as the

sister taxon 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 clade formed by ''Luopingosaurus'' and ''

Honghesaurus ''Honghesaurus'' is an extinct genus of pachypleurosaur from the Anisian-age Guanling Formation of China. The type specimen measures about in total body length. Classification The cladogram below follows Xu and colleagues (2022), when they use ...

''. The results of their

are shown in the

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

below:

References

Fossil taxa described in 2008 Monotypic prehistoric reptile genera Sauropterygian genera Middle Triassic reptiles of Asia Reptiles of China Aquatic reptiles Anisian life Anisian genus first appearances Guanling Formation {{triassic-reptile-stub