''Baisesaurus'' (meaning "

Baise Baise (; local pronunciation: ), or Bose, is the westernmost prefecture-level city of Guangxi, China bordering Vietnam as well as the provinces of Guizhou and Yunnan. The city has a population of 4.3 million, of which 1.4 million live in the ur ...

lizard") is an extinct genus of ichthyosauromorph from the early

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 ...

(

Spathian 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 divid ...

) Luolou Formation of Guangxi, China. The genus contains a single species, ''B. robustus'', known from a partial

postcrania Postcrania (postcranium, adjective: postcranial) in zoology and vertebrate paleontology is all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g. of dinosaurs or other extinct tetrapods, consist of partial or isolated s ...

l skeleton.

Discovery and naming

The ''Baisesaurus''

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 seve ...

specimen, CUGW VH107, was discovered in 2018 in a layer of the Luolou Formation in the Nanpanjiang Basin of Zhebao Township,

Longlin County Longlin Various Nationalities (Gezu) Autonomous County () is an autonomous county, under the jurisdiction of the prefecture-level city of Baise, in the west of Guangxi, China, bordering Guizhou Province to the north. As of 2019, the county's popu ...

, Guangxi region, China. The specimen consists of assorted

ribs The rib cage, as an enclosure that comprises the ribs, vertebral column and sternum in the thorax of most vertebrates, protects vital organs such as the heart, lungs and great vessels. The sternum, together known as the thoracic cage, is a semi ...

gastralia Gastralia (singular gastralium) are dermal bones found in the ventral body wall of modern crocodilians and tuatara, and many prehistoric tetrapods. They are found between the sternum and pelvis, and do not articulate with the vertebrae. In thes ...

, a limb element (likely a

radius In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...

), 12

vertebral centra The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...

, and seven

neural arches The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristi ...

. In 2022, Ren ''et al''. described ''Baisesaurus robustus'', a new genus and species of

basal Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''. Science * Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure * Basal (medicine), a minimal level that is nec ...

ichthyosauromorph. The generic name, "''Baisesaurus''", combines a reference to the type locality in

, China, with the

Greek Greek may refer to: Greece 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 ...

"saurus", meaning "lizard". The specific name, "''robustus''", means "robust".

Description

''Baisesaurus'' was likely at least long. It was more similar to ''

Utatsusaurus ''Utatsusaurus hataii'' is the earliest-known ichthyopterygian which lived in the Early Triassic period (c. 245–250 million years ago). It was nearly long with a slender body. The first specimen was found in Utatsu-cho (now part of Minamisan ...

'' than to any other ichthyosauromorph, with similar size and anatomical traits. It can be inferred from related animals that ''Baisesaurus'' was a strong swimmer with long, compact

forelimb A forelimb or front limb is one of the paired articulated appendages (limbs) attached on the cranial (anterior) end of a terrestrial tetrapod vertebrate's torso. With reference to quadrupeds, the term foreleg or front leg is often used instead. ...

bones.

Classification

''Baisesaurus'' likely represents a

member of the clade Ichthyosauromorpha. The describing authors explain that it may represent a member of the

Ichthyopterygia Ichthyopterygia ("fish flippers") was a designation introduced by Sir Richard Owen in 1840 to designate the Jurassic ichthyosaurs that were known at the time, but the term is now used more often for both true Ichthyosauria and their more primitiv ...

. However, such a classification is highly tentative.

References

{{Taxonbar, from=Q111702270 Sauropsida Fossil taxa described in 2022 Triassic reptiles of Asia Ichthyosauromorph genera Triassic ichthyosauromorphs Paleontology in Guangxi