Mamenchisauridae is a family of

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 ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

s belonging to the

Eusauropoda Eusauropoda (meaning "True Lizard Foot") is a derived clade of sauropod dinosaurs. Eusauropods represent the node-based group that includes all descendant sauropods starting with the basal eusauropods of '' Shunosaurus'', and possibly '' Barapas ...

known from the Jurassic and Early Cretaceous of Asia and Africa. Mamenchisaurids are characterized by their proportionately extremely long necks. Some members of the group reached gigantic sizes, amongst the largest of all sauropods.

Classification

The family Mamenchisauridae was first erected by Chinese paleontologists

Yang Zhongjian Yang Zhongjian, also Yang Chung-chien (; 1 June 1897 – 15 January 1979), courtesy name Keqiang (), also known as C.C. (Chung Chien) Young, was a Chinese paleontologist and zoologist. He was one of China's foremost vertebrate paleontologists. ...

("C.C. Young") and

Zhao Xijin Zhao Xijin (赵喜进; born c. 1935 died July 21, 2012) was a Chinese paleontologist notable for having named numerous dinosaurs. He was a professor at Beijing's Institute of Vertebrate Paleontology and Paleoanthropology. Biography Zhao Xijin was ...

in 1972, in a paper describing ''

Mamenchisaurus hochuanensis ''Mamenchisaurus'' ( , or spelling pronunciation ) is an extinct genus of sauropod dinosaurs known for their remarkably long necks which made up nearly half the total body length. Numerous species have been assigned to the genus; however, the val ...

''.Young, C.C. and Zhao, X. (1972). "''Mamenchisaurus hochuanensis sp. nov.''". ''Institute of Vertebrate Palaeontology and Palaeoanthropology Monographs'' Series A 8: 1-30. A comprehensive analysis of Mamenchisauridae was presented by Moore et al., 2020, including several named species. Notably, some iterations of their analyses recovered ''

Euhelopus ''Euhelopus'' is a genus of sauropod dinosaur that lived between 145 and 133 million years ago during the Berriasian and Valanginian ages of the Early Cretaceous in what is now Shandong Province in China. It was a large quadrupedal herbivore. Lik ...

'' and kin, usually considered

somphospondyli Somphospondyli is an extinct clade of titanosauriformes, titanosauriform sauropods that lived from the Late Jurassic until the end of the Late Cretaceous, comprising all titanosauriforms more closely related to Titanosauria proper than Brachiosau ...

ans, as relatives of mamenchisaurids, mirroring earlier conceptions about the family. The 2023 redescription of ''Mamenchisaurus sinocanadorum'' incorporated updated versions of a matrix from Moore et al. (2020). These results are displayed in the

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

below:

Paleobiology

Long-bone histology enables researchers to estimate the age that a specific individual reached. A study by Griebeler et al. (2013) examined long bone histological data and concluded that the unnamed mamenchisaurid SGP 2006/9 weighed , reached sexual maturity at 20 years and died at age 31.

Paleoecology

Fossils of ''Mamenchisaurus'' and ''Omeisaurus'' have been found in the

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 ...

, dating to the Oxfordian-Tithonian interval, around 159-150 Ma (million years ago). ''Chuanjiesaurus'' fossils date between 166.1 and 163.5 Ma, while those of ''Eomamenchisaurus'' were found in the Zhanghe Formation, believed to be around 175.6-161.2 million years old. Fossils of ''Tonganosaurus'' date to even earlier, from the (

Pliensbachian The Pliensbachian is an age of the geologic timescale and stage in the stratigraphic column. It is part of the Early or Lower Jurassic Epoch or Series and spans the time between 192.9 ±0.3 Ma and 184.2 ±0.3 Ma (million years ago). The Plie ...

) Early Jurassic. 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 ...

taxon ''

Wamweracaudia ''Wamweracaudia'' is a large herbivorous sauropod dinosaur from the Late Jurassic Tendaguru Formation of Tanzania, Africa, 155-145 million years ago. Discovery and naming During the German expeditions to the Tendaguru in German East Africa betwe ...

'' from Tanzania extends the geographic distribution of Mamenchisauridae into Africa, while fossil remains from the

Itat Formation The Itat Formation (Russian: итатская свита) is a geologic formation in western Siberia. It was deposited in the Bajocian to Bathonian ages of the Middle Jurassic. Dinosaur remains are among the fossils that have been recovered from ...

in Russia suggest they also reached Siberia. Additionally, an indeterminate cervical vertebra from the

Phu Kradung Formation The Early Cretaceous Phu Kradung Formation is the lowest member of the Mesozoic Khorat Group which outcrops on the Khorat Plateau in Isan, Thailand. This geological formation consists of micaceous, brown to reddish-brown siltstone beds with mino ...

of Thailand demonstrates survival of Mamenchisauridae into the Cretaceous combined with new radiometric dates for the Suining Formation that has yielded fossils of ''Mamenchisaurus anyuensis''.

References

Sources

* {{Taxonbar, from=Q138692 Dinosaur families