''Allognathosuchus'' (meaning "other jaw crocodile") is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus of alligatorine crocodylian with a complicated

taxonomic Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

history. It was named in 1921. Allognathosuchus gracilis

Description

''Allognathosuchus'' was a medium-sized predator up to 1.5 m in length. This alligatorine is known for its stout jaws and bulbous teeth, found near the rear of the tooth row in upper and lower jaws. These adaptations have historically been interpreted as having been for crushing

mollusks Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

. Isolated bulbous teeth are often assigned to this genus, although such teeth are known from other crocodyliform lineages.

Taxonomy

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 The Paleogene ( ; British English, also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period, geologic period and system that spans 43 million years from the end of the Cretaceous Period million yea ...

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 The North American land mammal ages (NALMA) establishes a geologic timescale for North American fauna beginning during the Late Cretaceous and continuing through to the present. These periods are referred to as ages or intervals (or stages when ref ...

. Several other genera and species were previously assigned to ''Allognathosuchus'', giving it a potential Upper Cretaceous-

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...

stratigraphic range, and a geographic range covering

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

, Europe, and Africa. Christopher Brochu reviewed the genus in 2004, and in light of the fragmentary remains of several of the species involved, recommended conservative use of the genus. He excluded '' Albertochampsa langstoni'', ''

Arambourgia gaudryi ''Arambourgia'' is an extinct monotypic genus of alligatorine crocodylian from Europe. It was named in 1905 as ''Allognathosuchus gaudryi''. It was made a separate genus ''Arambourgia'' in 1940. This was synonymized with '' Allognathosuchus haup ...

'', and ''

Wannaganosuchus brachymanus ''Wannaganosuchus'' (meaning "Wannagan crocodile", in reference to the Wannagan Creek site where it was discovered) is an extinct genus of small alligatorid crocodylian. It was found in Late Paleocene-age rocks of Billings County, North Dakota, ...

'' from ''Allognathosuchus'', and resurrected ''

Hassiacosuchus ''Hassiacosuchus'' is an extinct genus of small alligatorid from the early Eocene of Germany, found at the Messel pit. It was named in 1935 by K. Weitzel, and the type species is ''H. haupti''. A second species, ''H. kayi'', was named in 1941 by ...

'' and '' Navajosuchus'' from synonymy with ''Allognathosuchus'' after finding them not to group with ''A. polyodon'' to the exclusion of other alligatorines. Recent studies have consistently resolved ''Allognathosuchus polyodon'' and ''Allognathosuchus wartheni'' as members of Alligatorinae, although their relative placement is disputed, as shown by the cladograms below. Cladogram from 2018 Bona ''et al.'' study: Cladogram from 2019 Massonne ''et al.'' study: Cladogram from 2020 Cossette & Brochu study:

References

{{Taxonbar, from=Q4733055 Alligatoridae Eocene crocodylomorphs Eocene reptiles of Europe Eocene reptiles of North America Prehistoric pseudosuchian genera Fossil taxa described in 1921