''Argochampsa'' (meaning "

Argo In Greek mythology, the ''Argo'' ( ; ) was the ship of Jason and the Argonauts. The ship was built with divine aid, and some ancient sources describe her as the first ship to sail the seas. The ''Argo'' carried the Argonauts on their quest fo ...

crocodile", in reference to the

mythological Myth is a genre of folklore consisting primarily of narratives that play a fundamental role in a society. For scholars, this is very different from the vernacular usage of the term "myth" that refers to a belief that is not true. Instead, the ...

''Argo'' of

Jason Jason ( ; ) was an ancient Greek mythological hero and leader of the Argonauts, whose quest for the Golden Fleece is featured in Greek literature. He was the son of Aeson, the rightful king of Iolcos. He was married to the sorceress Med ...

) is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

eusuchia Eusuchia is a clade of neosuchian Crocodylomorpha, crocodylomorphs that first appeared in the Early Cretaceous, which includes modern Crocodilia, crocodilians. Along with Dyrosauridae and Sebecosuchia, they were the only crocodyliformes who survi ...

n crocodylomorph, usually regarded as a gavialoid

crocodilia Crocodilia () is an order of semiaquatic, predatory reptiles that are known as crocodilians. They first appeared during the Late Cretaceous and are the closest living relatives of birds. Crocodilians are a type of crocodylomorph pseudosuchia ...

n, related to modern

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

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), ...

Morocco Morocco, officially the Kingdom of Morocco, is a country in the Maghreb region of North Africa. It has coastlines on the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to Algeria–Morocc ...

. Described by Hua and Jouve in 2004, the

type species In International_Code_of_Zoological_Nomenclature, 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 spe ...

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, 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 mammals h ...

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 In vertebrates, the maxilla (: maxillae ) 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 two maxil ...

(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 Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spina ...

e, the

upper arm The upper limbs or upper extremities are the forelimbs of an upright-postured tetrapod vertebrate, extending from the scapulae and clavicles down to and including the digits, including all the musculatures and ligaments involved with the should ...

, and

armor Armour (Commonwealth English) or armor (American English; see American and British English spelling differences#-our, -or, spelling differences) is a covering used to protect an object, individual, or vehicle from physical injury or damage, e ...

has been recovered. ''Argochampsa'' had concave depressions on the internal surface of the lacrimal and prefrontal bones, indicating the presence of salt glands. Hua and Jouve performed a cladistic analysis incorporating their new

taxon In biology, a taxon (back-formation from ''taxonomy''; : 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 name and ...

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

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

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 Saskatchew ...

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

'', ''

Eosuchus ''Eosuchus'' ("dawn crocodile") is an extinct genus of eusuchian crocodylomorph, traditionally regarded as a gavialoid crocodilian. It might have been among the most basal of all gavialoids, lying crownward of all other known members of the ...

'', ''

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

'' and ''

Thoracosaurus ''Thoracosaurus'' (chest lizard) is an extinct genus of long-snouted eusuchian which existed during the Late Cretaceous and Early Paleocene in North America and Europe. Taxonomy ''Thoracosaurus'' had traditionally been thought to be related to ...

''.

References

External links

''Argochampsa''
in the

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

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