''Aprosuchus'' is a genus of small-bodied

Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

atoposaurid

Eusuchian Eusuchia is a clade of neosuchian crocodylomorphs that first appeared in the Early Cretaceous, which includes modern crocodilians. Along with Dyrosauridae and Sebecosuchia, they were the only crocodyliformes who survived the K-Pg extinction. ...

from the Hateg Basin,

Romania Romania is a country located at the crossroads of Central Europe, Central, Eastern Europe, Eastern and Southeast Europe. It borders Ukraine to the north and east, Hungary to the west, Serbia to the southwest, Bulgaria to the south, Moldova to ...

Discovery and naming

''Aprosuchus'' is known from an incomplete three-dimensional skull and closely associated mandibles (

Holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

UBB V.562/1) as well as a cervical vertebrae found in association with the cranial remains (referred specimen UBB V.562/2). The fossils were found in Maastrichtian sediments of the Pui Gater locality in the Hateg Basin in modern day

Transylvania Transylvania ( or ; ; or ; Transylvanian Saxon dialect, Transylvanian Saxon: ''Siweberjen'') is a List of historical regions of Central Europe, historical and cultural region in Central Europe, encompassing central Romania. To the east and ...

, Romania. The name derives from the Hungarian "apró" meaning small and the Ancient Greek σοῦχος, soukhos ("crocodile"). The species name ghirai honors Ioan Ghira from the Babeș-Bolyai University, Cluj-Napoca, for his contributions to

Herpetology Herpetology (from Ancient Greek ἑρπετόν ''herpetón'', meaning "reptile" or "creeping animal") is a branch of zoology concerned with the study of amphibians (including frogs, salamanders, and caecilians (Gymnophiona)) and reptiles (in ...

Description

''Aprosuchus'' was a small sized brevirostrine Eusuchian with an estimated body length of 600 mm. It differs from other crocodylomorphs through large palpebral strongly fused to the orbital margin of the prefrontals and frontals and partly overlapping the prefrontal and lacrimal and heterodont dentition. ''Aprosuchus'' dentition preserves at least four different morphotypes, pseudocaniniforms, pseudoziphodont lanceolate, ziphodont lanceolate and ‘low-crowned’ teeth. A further

autapomorphy In phylogenetics, an autapomorphy is a distinctive feature, known as a Synapomorphy, derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or Outgroup (cladistics), outgroup taxa, not ...

is the w-shaped overlap between the nasals and prefrontals which differentiates ''Aprosuchus'' from ''

Sabresuchus ''Sabresuchus'' is an extinct genus of neosuchian crocodyliform from the Cretaceous of Europe. The name is derived from 'Sabre' in reference to the enlarged and curved fifth maxillary tooth, and 'suchus' from the Ancient Greek for crocodile. Ta ...

symplesiodon''. The presence of four different tooth morphotypes casts doubt over the identification of atoposaurids based on teeth beyond a family level.

Phylogeny

The following phylogenetic tree is based on the results of Venczel and Codrea 2019 using their strict consensus tree resulted from the four most parsimonious trees (Alligatorium excluded). They recovered that ''Aprosuchus ghirai'' appeared to be closely allied to other atoposaurids while ''Wannchampsus'' and the Glen Rose Form stood outside of the clade, but still closer to atoposaurids than to paralligatorids. The paper's strict consensus tree resulted from the two most parsimonious trees (Alligatorium included) recovered similar results, retaining the sister group relationship between the ''Wannchampsus'' + Glen Rose Form clade as well as the sister group relationship between atoposaurids and paralligatorids.

Paleobiology

The presence of the fossil remains of two distinct genera of atoposaurids, alongside tentatively referred isolated teeth of the possibly

durophagous Durophagy is the eating behavior of animals that consume hard-shelled or exoskeleton-bearing organisms, such as corals, shelled mollusks, or crabs. It is mostly used to describe fish, but is also used when describing reptiles, including fossil t ...

Eusuchian ''

Acynodon ''Acynodon'' is an extinct genus of eusuchian crocodylomorph from the Late Cretaceous, with fossils found throughout Southern Europe. Classification The genus ''Acynodon'' contains three species: ''A. iberoccitanus'', ''A. adriaticus'', and ''A. ...

'' (cf. ''Acynodon'' sp.) and the larger ''

Allodaposuchus ''Allodaposuchus'' is an extinct genus of crocodyliforms that lived in what is now southern Europe during the Campanian and Maastrichtian stages, and possibly the Santonian stage, of the Late Cretaceous. Although generally classified as a non-cro ...

'' implies the existence of a diverse and complex ecosystem present on the Transylvanian landmass during the Maastrichtian. In this ecosystem the small bodied ''Aprosuchus'' would have most likely preyed on invertebrates and small vertebrates. The presence of ''Aprosuchus'' suggests that survivors of the Late Jurassic/Early Cretaceous atoposaurid lineage managed to survive up to the Late Cretaceous by colonising complex island ecosystems in the archipelagos of the Eastern Tethys.

References

{{Taxonbar, from=Q108697617 Atoposauridae Early Cretaceous reptiles of Europe Prehistoric pseudosuchian genera