Mamenchisauridae

Omeisauridae Wilson, 2002

Mamenchisauridae is a family of sauropod dinosaurs. The family was first named by Chinese paleontologists C.C. Young and X. Zhao in 1972, in a paper describing Mamenchisaurus. Other mamenchisaurids may include Chuanjiesaurus, Datousaurus, Eomamenchisaurus, Huangshanlong, Hudiesaurus, Qijianglong, Tienshanosaurus, Omeisaurus, and Tonganosaurus, Xinjiangtitan, Yuanmousaurus, Zigongosaurus . Fossils of Mamenchisaurus and Omeisaurus have been found in the Shangshaximiao Formation, dating to the Oxfordian stage, around 161.2-155.7 Ma (million years ago). Chuanjiesaurus fossils date between 175.6-161.2 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 Early Jurassic.

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 25,075 kilograms (27.6 short tons), reached sexual maturity at 20 years and died at age 31.