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Argochampsa Temporal range: Paleocene, 66–56 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Life Restoration
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Archosauria
Clade:	Pseudosuchia
Clade:	Crocodylomorpha
Clade:	Crocodyliformes
Clade:	Eusuchia
Genus:	†Argochampsa Hua & Jouve 2004
Type species
Argochampsa krebsi Hua & Jouve 2004

Argochampsa (meaning "Argo crocodile", in reference to the mythological Argo of Jason) is an extinct genus of eusuchian crocodylomorph, usually regarded as a gavialoid crocodilian, related to modern gharials. It lived in the Paleocene of Morocco. Described by Hua and Jouve in 2004, the type species is A. krebsi, with the species named for Bernard Krebs [de]. 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 premaxillae 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 main tooth-bearing bone of the upper jaw). The nasal bones 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 vertebrae, the upper arm, and armor has been recovered.

Hua and Jouve performed a cladistic analysis incorporating their new taxon, and found Argochampsa to be a gavialoid, but outside of the clade Gavialidae. They noted that the snout shape of Argochampsa is unusual among crocodilians, with only pholidosaurids and Terminonaris 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 clade of non-crocodylian eusuchians that also included the genera Eogavialis, Eosuchus, Eothoracosaurus and Thoracosaurus.

References

1. Rio, Jonathan P.; Mannion, Philip D. (6 September 2021). "Phylogenetic analysis of a new morphological dataset elucidates the evolutionary history of Crocodylia and resolves the long-standing gharial problem". PeerJ. 9: e12094. doi:10.7717/peerj.12094. PMC 8428266. PMID 34567843.
2. ^ Hua, Stephane; Jouve, Stéphane (2004). "A primitive marine gavialoid from the Paleocene of Morocco" (PDF). Journal of Vertebrate Paleontology. 24 (2): 341–350. doi:10.1671/1104. S2CID 86497272.
3. Jouve, Stéphane; Iarocheneb, Mohamed; Bouyac, Baâdi; Amaghzaz, Mbarek (2006). "New material of Argochampsa krebsi (Crocodylia: Gavialoidea) from the Lower Paleocene of the Oulad Abdoun Basin (Morocco): phylogenetic implications". Geobios. 39 (6): 817–832. doi:10.1016/j.geobios.2005.07.003.
4. Michael S. Y. Lee; Adam M. Yates (2018). "Tip-dating and homoplasy: reconciling the shallow molecular divergences of modern gharials with their long fossil record". Proceedings of the Royal Society B: Biological Sciences. 285 (1881): 20181071. doi:10.1098/rspb.2018.1071. PMC 6030529. PMID 30051855.

External links

• Argochampsa in the Paleobiology Database

v t e Neosuchia
Kingdom: Animalia Phylum: Chordata Class: Sauropsida Clade: Pseudosuchia Clade: Metasuchia Pseudosuchia see Pseudosuchia Neosuchia see below↓
Neosuchia Neosuchia †Burkesuchus †Isisfordia †Karatausuchus †Khoratosuchus †Montsecosuchus †Stolokrosuchus? †Susisuchus †Tadzhikosuchus? †Wahasuchus? †Zhyrasuchus? †Thalattosuchia? †Tethysuchia Pholidosauridae Anglosuchus Chalawan Crocodilaemus Dakotasuchus Elosuchus Meridiosaurus Oceanosuchus Pholidosaurus Sarcosuchus Terminonaris Vectisuchus Woodbinesuchus Dyrosauridae Acherontisuchus Anthracosuchus Arambourgisuchus Atlantosuchus Brachiosuchus Cerrejonisuchus Chenanisuchus Congosaurus Dorbignysuchus Dyrosaurus Fortignathus Guarinisuchus Hyposaurus Luciasuchus Phosphatosaurus Rhabdognathus Rodeosuchus Sabinosuchus? Sokotosuchus Tilemsisuchus †Atoposauridae Alligatorellus Alligatorium Aprosuchus Atoposaurus Knoetschkesuchus Sabresuchus Theriosuchus Varanosuchus †Stomatosuchidae Laganosuchus Stomatosuchus †Paluxysuchidae Deltasuchus Paluxysuchus †Goniopholididae Amphicotylus Anteophthalmosuchus Calsoyasuchus Coelosuchus Denazinosuchus Diplosaurus Eutretauranosuchus Goniopholis Hulkepholis Nannosuchus Ophiussasuchus Oweniasuchus Pinacosuchus? Siamosuchus Sunosuchus Symptosuchus? †Bernissartiidae Bernissartia Koumpiodontosuchus †Paralligatoridae Batrachomimus Brillanceausuchus Kansajsuchus Paralligator Rugosuchus Scolomastax Shamosuchus Tarsomordeo Turanosuchus Wannchampsus Yanjisuchus Eusuchia see below↓
Eusuchia Eusuchia †Borealosuchus †Confractosuchus †Dolichochampsa †Gilchristosuchus †Heterosuchus †Isisfordia? †Portugalosuchus †Pristichampsus †Susisuchus? †Titanochampsa? †Atoposauridae? †Bernissartiidae? †Paralligatoridae? †Hylaeochampsidae Acynodon? Hylaeochampsa Iharkutosuchus Pachycheilosuchus? Pietraroiasuchus Turcosuchus Unasuchus †Allodaposuchidae Agaresuchus Allodaposuchus Arenysuchus? Ischyrochampsa Lohuecosuchus Massaliasuchus Musturzabalsuchus? †Aegyptosuchidae Aegyptosuchus Aegisuchus †"Thoracosaurs" Argochampsa Eogavialis Eosuchus Eothoracosaurus Thoracosaurus †Planocraniidae Boverisuchus Duerosuchus Planocrania Crocodilia see Crocodilia for extant taxa, and Extinct Crocodilia for extinct ones
See also: Coelognathosuchia Category

• Neosuchians
• Prehistoric pseudosuchian genera
• Prehistoric marine crocodylomorphs
• Paleocene crocodylomorphs
• Paleocene reptiles of Africa