''Wumengosaurus'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

aquatic

reptile Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephalians ( ...

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 Ep ...

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 mudston ...

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 t ...

, southwestern

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

. It was originally described as a basal

eosauropterygia Sauropterygia (" lizard flippers") is an extinct taxon of diverse, aquatic reptiles that developed from terrestrial ancestors soon after the end-Permian extinction and flourished during the Triassic before all except for the Plesiosauria bec ...

n 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 th ...

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 narr ...

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 well- ...

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

pachypleurosaurid left, 220px, '' Pachypleurosaurus'' Pachypleurosauria is an extinct clade of primitive sauropterygian reptiles that vaguely resembled aquatic lizards, and were limited to the Triassic period. They were elongate animals, ranging in size from , ...

, 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 t ...

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 used ...

''. 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 d ...

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