''Eumetabolodon'' 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 ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

procolophonine Procolophoninae is an extinct subfamily of procolophonid parareptiles from the late Early Triassic to the early Middle Triassic (Olenekian and Anisian stages) of Africa, Antarctica, Asia, Europe and South America. Currently, the oldest-known p ...

procolophonid Procolophonidae is an extinct family of small, lizard-like parareptiles known from the Late Permian to Late Triassic that were distributed across Pangaea, having been reported from Europe, North America, China, South Africa, South America, Antarc ...

parareptile Parareptilia ("at the side of reptiles") is a subclass or clade of basal sauropsids (reptiles), typically considered the sister taxon to Eureptilia (the group that likely contains all living reptiles and birds). Parareptiles first arose near the ...

from early and middle

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...

(

Induan The Induan is the first age of the Early Triassic epoch in the geologic timescale, or the lowest stage of the Lower Triassic series in chronostratigraphy. It spans the time between 251.902 Ma and Ma (million years ago). The Induan is sometimes ...

to earliest

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 ...

stages) deposits of

Nei Mongol Inner Mongolia, officially the Inner Mongolia Autonomous Region, is an autonomous region of the People's Republic of China. Its border includes most of the length of China's border with the country of Mongolia. Inner Mongolia also accounts for a ...

, northern

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 ...

. Two species of ''Eumetabolodon'' were named by J. L. Li in

1983 The year 1983 saw both the official beginning of the Internet and the first mobile cellular telephone call. Events January * January 1 – The migration of the ARPANET to Internet protocol suite, TCP/IP is officially completed (this is consid ...

and the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

is ''Eumetabolodon bathycephalus''.

Discovery

The type species is known from the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

IVPP The Institute of Vertebrate Paleontology and Paleoanthropology (IVPP; ) of China is a research institution and collections repository for fossils, including many dinosaur and pterosaur specimens (many from the Yixian Formation). As its name suggest ...

V6064, a nearly complete

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...

which was collected in the Zhuengeerqi locality, from the upper Heshanggou Formation (

Olenekian In the geologic timescale, the Olenekian is an age in the Early Triassic epoch; in chronostratigraphy, it is a stage in the Lower Triassic series. It spans the time between Ma and Ma (million years ago). The Olenekian is sometimes divided into ...

and earliest

stages),

Ordos Basin The Ordos Plateau, also known as the Ordos Basin or simply the Ordos, is a highland sedimentary basin in northwest China with an elevation of , and consisting mostly of land enclosed by the Ordos Loop, a large northerly rectangular bend of the Y ...

. A second specimen, IVPP V6070 was collected in the Zhuengeerqi locality, from the

Ermaying Formation The Ermaying Formation is a sedimentary succession of Anisian (Middle Triassic) age. It is found in the Shaanxi Province of China. It is composed of an up to 600 m thick sequence of mudstone and sandstone. It is famous for its fossils of tetrapods. ...

(upper Olenekian stage), Ordos Basin. Additional 17 specimens, IVPP V6065-69, V6166 (1&2), V6167, V6168 (1&2), V6169-75, were collected in the Gucheng locality, from the upper Heshanggou Formation, Ordos Basin. ''"E." dongshengensis'' is known only from the holotype IVPP V6073, a partial skull including right

frontal Front may refer to: Arts, entertainment, and media Films * ''The Front'' (1943 film), a 1943 Soviet drama film * ''The Front'', 1976 film Music *The Front (band), an American rock band signed to Columbia Records and active in the 1980s and ea ...

, prefrontal, lacrimal,

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...

with seven teeth and the right ramus of

lower jaw In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

. It was collected in the Wusilangou locality near

Dongsheng Dongsheng District ( Mongolian: ''Düŋšėŋ toɣoriɣ''; ; alternate spelling English: Koshang; Turkic: Košang) is a District and the seat of Ordos City, Inner Mongolia, People's Republic of China. It has a district population of 574,242. Th ...

(also in Nei Mongol), from the

Early Triassic The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between Ma and Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which is a un ...

Shihtienfeng Formation.

Phylogeny

Recent

cladistic Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups (" clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived char ...

analyses suggested that ''Eumetabolodon'' is a

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

genus; the type species represents a relatively derived procolophonine, whereas ''"E." dongshengensis'' is a more basal procolophonid of the subfamily

Theledectinae Theledectinae is an extinct subfamily of parareptiles within the family Procolophonidae. Theledectines existed in South Africa, China and Australia during the Early-Middle Triassic period (Induan to Anisian stages). Theledectinae was named by Jua ...

. In 2020 a separate genus ''

Youngetta ''Youngetta'' is an extinct genus of procolophonid from the Early Triassic of 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 ...

'' was named. 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 follows the topology from a 2012 analysis by Cisneros.

References

{{Taxonbar, from=Q5409570 Procolophonines Early Triassic reptiles of Asia Fossil taxa described in 1983 Middle Triassic reptiles of Asia Anisian life Prehistoric reptile genera