Atoposauridae

Atoposauridae is an extinct family of neosuchian crocodyliforms, known from the Jurassic and Cretaceous of Eurasia. Characterised by their small size and their heterodont (having multiple tooth types) dentition, they are thought to have lived in terrestrial and semi-aquatic environments,^[1] and to have consumed small prey such as fish, insects and mammals.^[1][2] The oldest records of the group are known from the Middle Jurassic of Britain.^[3] The majority of the family are known from Late Jurassic to Early Cretaceous deposits in France, Portugal, and Bavaria in southern Germany.^[1][4][5] The discovery of the genus Aprosuchus, however, extends the duration of the lineage to the end of the Cretaceous in Romania.^[6]

Atoposauridae Temporal range: Middle Jurassic–Late Cretaceous PreꞒ Ꞓ O S D C P T J K Pg N
Specimen of Alligatorellus
Life restoration of Knoetschkesuchus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Archosauria
Clade:	Pseudosuchia
Clade:	Crocodylomorpha
Clade:	Eusuchia
Family:	†Atoposauridae Gervais, 1871
Genera
†Alligatorellus †Alligatorium †Aprosuchus †Atoposaurus †Knoetschkesuchus †Montsecosuchus? †Theriosuchus? †Varanosuchus
Synonyms
Alligatorellidae Tornier, 1933

Classification

Atoposaurids are universally considered members of Neosuchia. Tennant et al. (2016) in their revision of the group, found atoposaurids to be basal neosuchians, and the group as traditionally defined to be paraphyletic with respect to Paralligatoridae, restricting Atoposauridae to only include the genera Alligatorium, Alligatorellus and Atoposaurus.^[1] However Schwarz et al, (2017) found the traditional Atoposauridae as a whole to be monophyletic and the sister group to Paralligatoridae within the Eusuchia.^[4] A similar result was found by Pochat-Cottilloux et al (2024).^[7]

Phylogeny

Cladogram modified from Buscalioni and Sanz (1988)^[8] and Buscalioni and Sanz (1990):^[9]

Atoposauridae	Alligatorium Alligatorellus Atoposaurus Montsecosuchus Theriosuchus