''Argochampsa'' (meaning "

Argo In Greek mythology the ''Argo'' (; in Greek: ) was a ship built with the help of the gods that Jason and the Argonauts sailed from Iolcos to Colchis to retrieve the Golden Fleece. The ship has gone on to be used as a motif in a variety of sour ...

crocodile", in reference to the

mythological Myth is a folklore genre consisting of narratives that play a fundamental role in a society, such as foundational tales or origin myths. Since "myth" is widely used to imply that a story is not objectively true, the identification of a narrat ...

''Argo'' of Jason) 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 Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of eusuchian

crocodylomorph Crocodylomorpha is a group of pseudosuchian archosaurs that includes the crocodilians and their extinct relatives. They were the only members of Pseudosuchia to survive the end-Triassic extinction. During Mesozoic and early Cenozoic times, cro ...

, usually regarded as a

gavialoid Gavialoidea is one of three superfamilies of crocodylians, the other two being Alligatoroidea and Crocodyloidea. Although many extinct species are known, only the gharial ''Gavialis gangeticus'' and the false gharial ''Tomistoma schlegelii'' are ...

crocodilia Crocodilia (or Crocodylia, both ) is an order of mostly large, predatory, semiaquatic reptiles, known as crocodilians. They first appeared 95 million years ago in the Late Cretaceous period ( Cenomanian stage) and are the closest living ...

n, related to modern

gharial The gharial (''Gavialis gangeticus''), also known as gavial or fish-eating crocodile, is a crocodilian in the family Gavialidae and among the longest of all living crocodilians. Mature females are long, and males . Adult males have a distinct b ...

s. It lived in the

Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), E ...

Morocco Morocco (),, ) officially the Kingdom of Morocco, is the westernmost country in the Maghreb region of North Africa. It overlooks the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to ...

. Described by Hua and Jouve in 2004, the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

is ''A. krebsi'', with the species named for . ''Argochampsa'' had a long narrow snout, and appears to have been marine in habits.

Description

''Argochampsa'' is based on OCP DEK-GE 1201, a nearly complete skull from the

Oulad Abdoun Basin The Oulad Abdoun Basin (also known as the Ouled Abdoun Basin or Khouribga Basin) is a phosphate sedimentary basin located in Morocco, near the city of Khouribga. It is the largest in Morocco, comprising 44% of Morocco's phosphate reserves, and a ...

, in the vicinity of Khouribga, Morocco. The skull, 43.3 centimeters long (17.0 in), had a long, narrow snout, marking it as a longirostrine crocodilian; the snout made up about 70% of the skull's length. The

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has b ...

e at the tip of the snout were downturned, and the tip somewhat squared off, with the first few tooth positions in a straight line perpendicular to the long axis of the skull. There were five teeth in each premaxilla and 26 in each

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...

(the main tooth-bearing bone of the upper jaw). The

nasal bone The nasal bones are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face and by their junction, form the bridge of the upper one third of the nose. Eac ...

s were fused, and there were several short diastemas or gaps in the tooth row at the tip of the snout. More recently, material from the lower jaw, neck and back

vertebra The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...

e, the

upper arm In human anatomy, the arm refers to the upper limb in common usage, although academically the term specifically means the upper arm between the glenohumeral joint (shoulder joint) and the elbow joint. The distal part of the upper limb between th ...

, and armor has been recovered. Hua and Jouve performed a cladistic analysis incorporating their new

taxon In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...

, and found ''Argochampsa'' to be a gavialoid, but outside of the

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

Gavialidae. They noted that the snout shape of ''Argochampsa'' is unusual among crocodilians, with only pholidosaurids and ''

Terminonaris ''Terminonaris'' is a genus of extinct pholidosaurid crocodyliforms that lived during the Late Cretaceous (Cenomanian and TuronianWu X-C, Russell AP, & Cumbaa SL. 2001. ''Terminonaris'' (Archosauria: Crocodyliformes): new material from Saskatche ...

'' having similarly shaped snout tips, and suggested that this layout may have facilitated precise occlusion. ''Argochampsa'' lived in an environment otherwise dominated by

dyrosaurid Dyrosauridae is a family of extinct neosuchian crocodyliforms that lived from the Late Cretaceous (Maastrichtian) to the Eocene. Dyrosaurid fossils are globally distributed, having been found in Africa, Asia, Europe, North America and South Amer ...

marine

crocodyliforms Crocodyliformes is a clade of crurotarsan archosaurs, the group often traditionally referred to as "crocodilians". They are the first members of Crocodylomorpha to possess many of the features that define later relatives. They are the only pseudo ...

. ''Argochampsa krebsi'' was included in the study on the phylogenetic relationships of putative fossil gavialoids published by Lee & Yates (2018). The authors considered it most likely that ''Argochampsa'' was not a gavialoid, or even a crocodylian, but rather a member of the

of non-crocodylian eusuchians that also included the genera ''

Eogavialis ''Eogavialis'' is an extinct genus of eusuchian crocodylomorph, usually regarded as a gavialoid crocodylian. It superficially resembles ''Tomistoma schlegelii'', the extant false gharial, and consequently material from the genus was originally re ...

'', '' Eosuchus'', ''

Eothoracosaurus ''Eothoracosaurus'' is an extinct monospecific genus of eusuchian Crocodylomorpha, crocodylomorphs found in Eastern United States which existed during the Late Cretaceous period. ''Eothoracosaurus'' is considered to belong to an informally named ...

'' and ''

Thoracosaurus ''Thoracosaurus'' is an extinct genus of eusuchian crocodylomorph which existed during the Late Cretaceous and Early Paleocene in North America and Europe. The taxon had traditionally been thought to be related to the modern false gharial, large ...

''.

References

External links

''Argochampsa''
in the

Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals, plants, and microorganisms. History The Paleobiology Database (PBDB) originated in the NCEAS-funded Phanerozoic Marine Pale ...

{{Taxonbar, from=Q4789641, from2=Q20717071 Neosuchians Prehistoric pseudosuchian genera Prehistoric marine crocodylomorphs Paleocene crocodylomorphs Paleocene reptiles of Africa