Tongnanlong

Tongnanlong is a genus of mamenchisaurid dinosaur from the Late Jurassic Suining Formation of Chongqing, China. The type species is Tongnanlong zhimingi.

Discovery and naming

The Tongnanlong holotype specimen, TNM 0254, consists of three dorsal and six caudal vertebrae, left shoulder girdle and hindlimb elements. It was discovered in 1998 during construction of a building along Dafo Street.
It was described as a new genus and species of dinosaur in 2025. The generic name, Tongnanlong, combines a reference to Tongnan District, Chongqing, where it was found, with the Chinese word long, meaning "dragon". The specific name, zhimingi, refers to prominent Chinese paleontologist Dong Zhiming.

Description

Tongnanlong is estimated as being up to long, making it one of the largest mamenchisaurids.

Classification

Wei et al. inserted Tongnanlong into the phylogenetic analysis previously used in the description of Jingiella. It placed Tongnanlong as a derived member of the Mamenchisauridae close to Mamenchisaurus. A cladogram adapted from their analysis is shown below:

Paleoenvironment

Other animals from the Suining Formation include fellow mamenchisaurid dinosaurs Qijianglong guokr and Mamenchisaurus anyuensis, the lungfish Ceratodus szechuanensis, and the turtle Plesiochelys tatsuensis.