Allognathosuchus (meaning "other jaw crocodile") is an extinct genus of alligatorine crocodylian with a complicated taxonomic history.

The type species, A. polyodon, is from the Eocene-age Bridger Formation of Wyoming; it is based on fossils that are difficult to distinguish from other Paleogene alligatorids.

A. heterodon is from the Eocene-age Wasatch Formation of Wyoming, A. wartheni is from the Eocene-age Wildwood Formation (also known as the "Wildwood alligatorid" and possibly two species), and A. woutersi, which may belong to Diplocynodon, instead, is from the Early Eocene of Belgium.

A. polyodon, A. heterodon, and A. wartheni span the Clarkforkian, Wasatchian, and Bridgerian North American Land Mammal Ages.

[4] Several other genera and species were previously assigned to Allognathosuchus, giving it a potential Upper Cretaceous-Oligocene stratigraphic range, and a geographic range covering North America, Europe, and Africa.