''Bashunosaurus'' is a genus of potentially macronarian sauropod dinosaur from the Middle

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...

Shaximiao Formation The Shaximiao Formation () is a Middle to Late Jurassic aged geological formation in Sichuan, China, most notable for the wealth of dinosaurs fossils that have been excavated from its strata. The Shaximiao Formation is exposed in and around the ...

of Kaijiang, China. The type and only species is ''Bashunosaurus kaijiangensis''.

Discovery

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 seve ...

of ''Bashunosaurus'', KM 20100, was discovered in sediments of the lower Shaximiao Formation in Maanping,

Sichuan Province Sichuan (; zh, c=, labels=no, ; zh, p=Sìchuān; alternatively romanized as Szechuan or Szechwan; formerly also referred to as "West China" or "Western China" by Protestant missions) is a province in Southwest China occupying most of th ...

, China. It consists of six

cervical vertebrae In tetrapods, cervical vertebrae (singular: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In ...

, eight

dorsal vertebrae In vertebrates, thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. In humans, there are twelve thoracic vertebrae and they are intermediate in size between the cervical ...

, a partial left

scapula The scapula (plural scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on eithe ...

, and a right

humerus The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a roun ...

ulna The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...

ilium Ilium or Ileum may refer to: Places and jurisdictions * Ilion (Asia Minor), former name of Troy * Ilium (Epirus), an ancient city in Epirus, Greece * Ilium, ancient name of Cestria (Epirus), an ancient city in Epirus, Greece * Ilium Building, a ...

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates wit ...

tibia The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...

, and

fibula The fibula or calf bone is a human leg, leg bone on the Lateral (anatomy), lateral side of the tibia, to which it is connected above and below. It is the smaller of the two bones and, in proportion to its length, the most slender of all the long ...

. An additional right ilium, specimen KM 20103, was assigned as a

paratype In zoology and botany, a paratype is a specimen of an organism that helps define what the scientific name of a species and other taxon actually represents, but it is not the holotype (and in botany is also neither an isotype nor a syntype). O ...

History

The name "Bashunosaurus kaijiangensis" first appeared in Ouyang's description of '' Abrosaurus'' in 1989, although without a description or diagnosis, making it a ''

nomen nudum In taxonomy, a ''nomen nudum'' ('naked name'; plural ''nomina nuda'') is a designation which looks exactly like a scientific name of an organism, and may have originally been intended to be one, but it has not been published with an adequate des ...

'' (i.e. a nickname that is unavailable for use as an actual scientific name). Li ''et al.'' (1999), however, attribute the naming to "Kuang, 1996", still considering it a ''nomen nudum''. Although it was finally formally named by Kuang in 2004, George Olshevsky's influential online ''Dinosaur Genera List'' continued to list it as a ''nomen nudum'' and possible synonym of '' Datousaurus''. It was largely ignored in modern literature until Dai ''et al.''s description of ''

Yuzhoulong ''Yuzhoulong'' (meaning "Chongqing dragon", after ''Yuzhou'', an early name for Chongqing) is a genus of macronarian sauropod dinosaur from the Middle Jurassic Shaximiao Formation of Chongqing, China. The type and only species is ''Yuzhoulong qur ...

'' in 2022, where it is discussed.

Description

As a sauropod, ''Bashunosaurus'' would have been a large quadrupedal

herbivore A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthp ...

with a robust body. Kuang (2004) estimated its length as about .

Classification

The precise classification of ''Bashunosaurus'' is unknown, with different authors proposing different ideas. Li ''et al.'' (1999) consider it a camarasaurid, while Kuang (2004) gives a more precise position in the Camarasaurinae, more derived than '' Abrosaurus'' but more

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 ...

than ''

Camarasaurus ''Camarasaurus'' ( ) was a genus of quadrupedal, herbivorous dinosaurs and is the most common North American sauropod fossil. Its fossil remains have been found in the Morrison Formation, dating to the Late Jurassic epoch (Kimmeridgian to Titho ...

''. Molina-Perez and Larramendi (2020) list it as a primitive

neosauropod Neosauropoda is a clade within Dinosauria, coined in 1986 by Argentine paleontologist José Bonaparte and currently described as '' Saltasaurus loricatus'', '' Diplodocus longus'', and all animals directly descended from their most recent common ...

similar to '' Bellusaurus'', ''

Daanosaurus ''Daanosaurus'' (meaning "Da'an lizard" after Da'an district in Zigong, Sichuan) was a genus of dinosaur. It was a sauropod which lived during the Late Jurassic ( Oxfordian - Tithonian stage, about 163 - 145 mya). It lived in what is now China (S ...

'', ''

Dashanpusaurus ''Dashanpusaurus'' (meaning "Dashanpu lizard" after the township it was discovered in) is an extinct genus of sauropod dinosaur that lived during the middle of the Jurassic period. The dinosaur was described in 2005 by Peng Guangzhao, Ye Yong, Gao ...

'' and '' Klamelisaurus'', although they comment that it is also "similar to ''Abrosaurus'' and '' Datousaurus''". Dai ''et al.'' (2022) compare the taxon to ''

'', noting the fact it was described as a macronarian, although they caution that a reappraisal is needed to confirm this in a cladistic context.

References

{{Sauropodomorpha, M. Middle Jurassic dinosaurs of Asia Macronarians Fossil taxa described in 2004 Paleontology in Sichuan