Chasmatosuchus was an archosauriform reptile from the early Triassic period of European Russia.

One of the earliest described archosauriforms, it was over 2 m long and is thought to have behaved like a modern crocodile.

Instead their position was found to be unresolved due to the fragmentary nature of the known material, however Chasmatosuchus is more likely to be intermediate between proterosuchids and erythrosuchids and possibly closely related to Sarmatosuchus otschevi and Cuyosuchus huenei.

[3] However, a 2023 study, also by Ezcurra et al, found Chasmatosuchus to be a true proterosuchid, distinct from Gamosaurus and Jaikosuchus based on vertebral differences, and that all three belonged to a new subfamily of the Proterosuchidae, the Chasmatosuchinae.

[4] Chasmatosuchus parvus, based on an anterior cervical vertebra, was synonymized with Macrocnemus in 1995.