Mamenchisauridae
Long-necked sauropods from Jurassic Asia.
Mamenchisauridae is a group of sauropod dinosaurs within Eusauropoda. Their fossils have been found in Asia, spanning the Jurassic and Early Cretaceous. The family is best known for having necks that are extremely long compared to the rest of the body. Some members grew to enormous sizes, ranking among the largest sauropods ever.
The family was first named in 1972 by Chinese paleontologists Yang Zhongjian and Zhao Xijin, in a paper describing the species *Mamenchisaurus hochuanensis*. A major study by Moore and colleagues in 2020 analyzed several named species within the family. In some versions of their analysis, the group *Euhelopus* and its relatives—usually classified as somphospondylians—were found to be close relatives of mamenchisaurids, matching older ideas about the family. Later studies built on this 2020 work, including a 2023 redescription of *Mamenchisaurus sinocanadorum*.
By studying the long-bone histology of a mamenchisaurid specimen known as SGP 2006/9, researchers estimated its weight at about 25,075 kilograms. The same study concluded it reached sexual maturity at 20 years old and died at age 31.
Fossils of *Mamenchisaurus* and *Omeisaurus* come from the Shaximiao Formation, which dates to between roughly 159 and 150 million years ago. *Chuanjiesaurus* fossils are from 166.1 to 163.5 million years ago, while *Eomamenchisaurus* was found in the Zhanghe Formation, dated to around 175.6 to 161.2 million years ago. *Tonganosaurus* fossils are even older, from the Early Jurassic. A single neck bone from the Phu Kradung Formation in Thailand, along with new dates for the Suining Formation (which yielded *Mamenchisaurus anyuensis*), shows that mamenchisaurids survived into the Cretaceous.
Quick Facts
- Taxon
- Mamenchisauridae
Facts from the source article.
Lore & Background
The family Mamenchisauridae was first erected by Chinese paleontologists Yang Zhongjian and Zhao Xijin in 1972, in a paper describing Mamenchisaurus hochuanensis. A comprehensive analysis by Moore et al. in 2020 included several named species and noted that some iterations recovered Euhelopus and kin, usually considered somphospondylians, as relatives of mamenchisaurids. Later publications built on this matrix, including the 2023 redescription of Mamenchisaurus sinocanadorum.
Reader's Guide
Mamenchisauridae represents a distinctive group of sauropods known for their exceptionally long necks, which set them apart from other Eusauropoda. Their fossils span the Jurassic and Early Cretaceous, with a geographic range extending from Asia to Africa, as shown by the Tendaguru Formation taxon Wamweracaudia from Tanzania and remains from the Itat Formation in Russia. The family's survival into the Cretaceous is evidenced by an indeterminate cervical vertebra from the Phu Kradung Formation of Thailand. Paleobiological studies, such as that by Griebeler et al. in 2013, used long-bone histology to estimate that the unnamed mamenchisaurid SGP 2006/9 weighed 25,075 kilograms, reached sexual maturity at 20 years, and died at age 31. The family's classification remains subject to ongoing analysis, with some studies suggesting relationships to somphospondylians like Euhelopus.
Did You Know?
- Some mamenchisaurids reached gigantic sizes, among the largest of all sauropods.
- The unnamed mamenchisaurid SGP 2006/9 weighed an estimated 25,075 kilograms and died at age 31.
- Fossils of Mamenchisauridae have been found in Asia.
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