Brachychampsa

Brachychampsa is an extinct genus of alligatoroid. Specimens have been found from New Mexico, Colorado, Wyoming,[3]  Montana,[1] [4] [5]  North and South Dakota,[6] New Jersey, and Saskatchewan. One specimen has been found from the Darbasa Formation of Kazakhstan, although the species status is indeterminant for the fossil. The genus first appeared during the late Campanian stage of the Late Cretaceous (Judithian North American stage) and became extinct during the early Danian stage of the Paleocene (Puercan North American stage), a few million years after the Cretaceous–Paleogene extinction event. Brachychampsa is distinguished by an enlarged fourth maxillary tooth in the upper jaw.

Brachychampsa's position within Alligatoroidea has undergone many revisions since it was first named. Originally it was placed within Alligatoridae, and was later refined to the Alligatorinae in 1964,[3]  only to be placed outside both Alligatorinae and Alligatoridae (but still within Alligatoroidea) in 1994.[7]  On the other hand, in the phylogenetic analysis conducted by Bona et al. (2018) Brachychampsa was recovered as an alligatorid, specifically as a stem-caiman.[8]