Shamosuchus

Not to be confused with Shamosaurus.

Shamosuchus is an extinct genus of neosuchian crocodyliform that lived during the Late Cretaceous (Campanian) period in what is now the Djadochta Formation of Mongolia, approximately 75 million to 71 million years ago.

Shamosuchus Temporal range: Late Cretaceous, 83.6–72.1 Ma[1] PreꞒ Ꞓ O S D C P T J K Pg N
Holotype specimen
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Archosauria
Clade:	Pseudosuchia
Clade:	Crocodylomorpha
Clade:	Neosuchia
Family:	†Paralligatoridae
Genus:	†Shamosuchus Mook, 1924
Type species
†Shamosuchus djadochtaensis Mook, 1924

Description

Skull and diagram of referred specimen

Shamosuchus reached up to 4 m long and had a rostrum of moderate length.^[2] In S. djadochtaensis, a perinarial fossa extended along the ventrolateral region of the narial opening. Where the premaxilla and maxilla articulate, the alveolar margin is continuous and is characterised by the absence of a notch for receiving the opposing mandibular tooth.^[3]

Taxonomy

The genus was named in 1924 by Charles C. Mook.^[4] Paralligator was synonymized with Shamosuchus by several authors.^[5][6][7] However, recent cladistic analysis of Paralligatoridae found the former genus to be distinct from the latter.^[8]

Phylogeny

Below are the results of a phylogenetic analysis by Pol et al., 2009 showing the position of Shamosuchus within Neosuchia:^[3]

Neosuchia	Theriosuchus Alligatorium Goniopholis simus Goniopholis stovalli Eutretauranosuchus Sunosuchus Calsoyasuchus Bernissartia 'Glen Rose form' Rugosuchus Shamosuchus Eusuchia Hylaeochampsa Borealosuchus Pristichampsus Crocodylia

Palaeobiology

The eye and nasal openings were not raised above the skull as in modern crocodilians, so that the animal would have to raise its head completely out of the water to breathe. As this cranial morphology does not suit an ambush predator, it lends support to the idea of a diet of aquatic invertebrates. The morphology of the teeth of Shamosuchus suggests they were adapted to crush bivalves, gastropods, and other animals with a shell or exoskeleton.^[4]