''Baotianmansaurus'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of somphospondylian

sauropod Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their b ...

. Its fossils were discovered in the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

Gaogou Formation of

Henan Province Henan; alternatively Honan is a province in Central China. Henan is home to many heritage sites, including Yinxu, the ruins of the final capital of the Shang dynasty () and the Shaolin Temple. Four of the historical capitals of China, Luo ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

. The type and only species is ''B. henanensis'' — named after the province in which it was found.

Discovery and naming

The fossils of ''Baotianmansaurus'' were discovered at a locality called Neixiang, near Nanyang City in the

. This locality is part of the Baotianman National Nature Reserve corresponds to the rocks of the Gaogou Formation. Dinosaur body fossils in this formation are rare, but a wide variety of

egg fossils Egg fossils are the fossilized remains of eggs laid by Geologic time, ancient animals. As evidence of the Physiology, physiological processes of an animal, egg fossils are considered a type of trace fossil. Under rare circumstances a fossil egg ma ...

from dinosaurs and other animals have been found. The

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

, and only known specimen of ''Baotianmansaurus'' was given the designation 41HIII-0200 and is stored at the Henan Geological Museum in

Zhengzhou Zhengzhou is the capital of Henan, China. Located in northern Henan, it is one of the nine National central city, national central cities in China, and serves as the political, economic, technological, and educational center of the province. Th ...

. It was described and given a name in April 2009 by a team of researchers including Zhang Xingliao,

Lü Junchang Lü Junchang (; 1965 – 9 October 2018) was a Chinese palaeontologist and professor at the Institute of Geology, Chinese Academy of Geological Sciences. An expert on Mesozoic reptiles, he described and named dozens of dinosaur and pterosaur taxa ...

, Xu Li, Li Jinhua, Hu Weiyong, Jia Songhai, Ji Qiang, and Zhang Chengjun in conjunction with the Henan Geological Museum, the

Chinese Academy of Geological Sciences The Chinese Academy of Geological Sciences (CAGS; ) is an institution that engages in geoscience research in the People's Republic of China. The academy was established in 1956 and reorganized in 1999. Administratively it is under the PRC Ministr ...

, and

Lanzhou University Lanzhou University () is a public university in Lanzhou, Gansu, China. It is affiliated with the Ministry of Education of China. The university is part of Project 211, Project 985, and the Double First-Class Construction. Founded in 1909, the ...

. The genus was named ''"Baotianmansaurus"'' after the Baotianman Nature Reserve and the traditional

Greek Greek may refer to: 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 of all kno ...

suffix ''"-saurus"'' meaning "lizard". The species epithet, ''"henanensis"'' is after the Henan province in which it was found.

Description

''Baotianmansaurus'' was a medium-sized sauropod. It was a very large animal in absolute terms, but not nearly as large as the largest of its contemporaries. The authors of its description did not provide an estimate of its in-life size, nor did they provide any measurements of the elements preserved. Rubén Molina-Pérez and Asier Larramendi estimated the full size of ''Baotianmansaurus'' at about long, tall at the shoulder, and weighing

Gregory S. Paul Gregory Scott Paul (born December 24, 1954) is an American freelance researcher, author and illustrator who works in paleontology. He is best known for his work and research on theropoda, theropod dinosaurs and his detailed illustrations, both l ...

published a slightly smaller estimate of long and weighing . The

of ''Baotianmansaurus'' is relatively incomplete. It consists of an incomplete dorsal vertebra from the upper back, another vertebra from the lower back, five

rib In vertebrate anatomy, ribs () are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the thoracic cavity, enabling the lungs to expand and thus facilitate breathing by expanding the ...

s, two partial

sacral vertebrae The sacrum (: sacra or sacrums), in human anatomy, is a triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30. The sacrum situates at the upper, back part of the pelvic cavity, ...

, an incomplete caudal vertebra, the distal end of a

scapula The scapula (: 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 either side ...

, and several bone fragments that were not able to be identified. These remains were sufficient to name a new genus and species. ''Baotianmansaurus'' can be distinguished from all other

s by the presence of the following autapomorphies: a spongy character of the back vertebrae, short

neural spine Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal ...

s on the vertebrae of the middle back, a developed system of 11 e on the vertebrae, apneumatic ribs, amphicoelous caudal vertebrae that are shorter than they are wide, and several specific features of the vertebral laminae.

Classification

The exact affinities of ''Baotianmansaurus'' have been controversial since it was first described. Zhang and colleagues originally assigned it to an indeterminate position in Titanosauriformes, outside of both Brachiosauridae and Somphospondyli. They remarked that it bears one of the autapomorphies of Somphospondyli, but that this was insufficient to assign it to that clade. Subsequent authors have recovered a wide variety of

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

positions for the genus. Philip Mannion and colleagues found it to be a member of Saltasauridae, closely related to '' Opisthocoelicaudia''. Alexander Averianov and Hans Dieter-Sues suggested that it was a

titanosaur Titanosaurs (or titanosaurians; members of the group Titanosauria) were a diverse group of sauropod dinosaurs, including genera from all seven continents. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still thr ...

outside of the clade

Lithostrotia Lithostrotia is a clade of derived titanosaur sauropods that lived during the Early Cretaceous and Late Cretaceous. The group was defined by Upchurch ''et al.'' in 2004 as the most recent common ancestor of ''Malawisaurus'' and ''Saltasaurus'' an ...

. A 2011 review of the evolution of Titanosauriformes found it to belong to

Euhelopodidae Euhelopodidae is a family of sauropod dinosaurs of disputed membership and affinities, which contains '' Euhelopus'' and its close relatives. Most proposed euhelopodids are from East Asia. Euhelopodidae was first recognized by Carl Wiman in 1929 ...

. A 2019 examination of sauropods from the

Tendaguru Formation The Tendaguru Formation, or Tendaguru Beds are a highly List of fossiliferous stratigraphic units in Tanzania, fossiliferous Lithostratigraphy, formation and Lagerstätte located in the Lindi Region of southeastern Tanzania. The formation represe ...

found a close relationship between ''Baotianmansaurus'', '' Dongyangosaurus'', and the

Diamantinasauria Diamantinasauria is an extinct clade of somphospondylan titanosauriform sauropod dinosaurs with close affinities to the Titanosauria, known from the early Late Cretaceous (Cenomanian-Turonian) of South America and Australia. It was named by Poro ...

. The next year, a phylogenetic analysis corroborated a close relationship with ''Dongyangosaurus'' as well as with '' Jiangshanosaurus'' in a clade at the base of Titanosauria. More recent analyses using various datasets have recovered ''Baotianmansaurus'' as either a non-titanosaur somphospondylian closely related to '' Huanghetitan'' or a basal member of Titanosauria closely related to ''

Andesaurus ''Andesaurus'' ( ; "Andes lizard") is a genus of basal titanosaurian sauropod dinosaur which existed during the middle of the Cretaceous Period in South America. Like most sauropods, it would have had a small head on the end of a long neck and a ...

'' and '' Abdarainurus''. The classification of titanosaurs and their relatives has generally been controversial, partly due to the fragmentary nature of many specimens, so the exact affinities of ''Baotianmansaurus'' remain unresolved, beyond it being a member of the large clade Somphospondyli. However, a close relationship with ''Dongyangosaurus'' has been corroborated by multiple analyses.

References

{{Portal bar, Dinosaurs, Paleontology, China Titanosauria Dinosaur genera Cenomanian dinosaurs Fossil taxa described in 2009 Taxa named by Lü Junchang Dinosaurs of China

Discovery and naming

Description

Classification

See also

References