Argochampsa is an extinct genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of gavialoid

Gavialoidea

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 possibly the False gharial Tomistoma schlegelii are alive today.-Classification:Gavialoidea contains the...

 crocodilia

Crocodilia

Crocodilia is an order of large reptiles that appeared about 84 million years ago in the late Cretaceous Period . They are the closest living relatives of birds, as the two groups are the only known survivors of the Archosauria...

n, related to modern gharial

Gharial

The gharial , , also called Indian gavial or gavial, is the only surviving member of the once well-represented family Gavialidae, a long-established group of crocodilians with long, slender snouts...

s. It lived in the Paleocene

Paleocene

The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...

 of Morocco

Morocco

Morocco , officially the Kingdom of Morocco , is a country located in North Africa. It has a population of more than 32 million and an area of 710,850 km², and also primarily administers the disputed region of the Western Sahara...

. Described by Hua and Jouve in 2004, the type species

Type species

In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...

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

Argochampsa is based on

Holotype

A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...

 OCP DEK-GE 1201, a nearly complete skull from the Oulad Abdoun Basin, in the vicinity of Khouribga

Khouribga

Khouribga is a city in Khouribga Province in the Chaouia-Ouardigha region of Morocco with a population of approximately 172,000. Khouribga owes its growth to the phosphate deposits nearby.-Geography:...

, 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

Premaxilla

The incisive bone is the portion of the maxilla adjacent to the incisors. It is a pair of small cranial bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. They are connected to the maxilla and the nasals....

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

Maxilla

The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...

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

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 form, by their junction, "the bridge" of the nose.Each has two surfaces and four borders....

s were fused, and there were several short diastemas

Diastema (dentistry)

Diastema is a space or gap between two teeth. Many species of mammals have diastemata as a normal feature, most commonly between the incisors and molars.-In humans:...

 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

Humerus

The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....

, and armor

Osteoderm

Osteoderms are bony deposits forming scales, plates or other structures in the dermal layers of the skin. Osteoderms are found in many groups of extant and extinct reptiles, including lizards, various groups of dinosaurs , crocodilians, phytosaurs, aetosaurs, placodonts, and hupehsuchians...

 has been recovered.

Hua and Jouve performed a cladistic analysis

Cladistics

Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...

 incorporating their new taxon

Taxon

|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...

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

Clade

A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...

 Gavialidae

Gavialidae

Gavialidae is a family of reptiles within the order Crocodilia. Gavialidae consists of only one surviving species, the gharial , which is native to India. Many extinct species are also known...

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

Pholidosauridae

Pholidosauridae is an extinct family of mesoeucrocodylian crocodylomorphs. Fossils have been found in the United States, Canada, China, Kyrgyzstan, Africa and Spain...

 and Terminonaris

Terminonaris

Terminonaris is a genus of extinct crocodilian reptiles that lived in the Late Cretaceous . Its remains are known from North America...

having similarly shaped snout tips, and suggested that this layout may have facilitated precise occlusion

Occlusion (dentistry)

Occlusion, in a dental context, means simply the contact between teeth. More technically, it is the relationship between the maxillary and mandibular teeth when they approach each other, as occurs during chewing or at rest....

. Argochampsa lived in an environment otherwise dominated by dyrosaurid

Dyrosauridae

Dyrosauridae is a family of extinct neosuchian crocodyliforms that lived from the Late Cretaceous to the Eocene. Fossils of this group have been found in almost every continent, specifically Africa, Asia, Europe, North America and South America....

 marine crocodyliforms

Crocodyliformes

Crocodyliformes is a clade of crurotarsan archosaurs, the group often traditionally referred to as "crocodilians."In 1988, Michael J. Benton and James M. Clark argued that all traditional names for well-known groups of animals should be restricted to their crown clades, that is, used only for...

.

External links

• Argochampsa in the Paleobiology Database
  Paleobiology Database
  ' is an online resource for information on the distribution and classification of fossil animals, plants, and microorganisms.-History:The Paleobiology Database was founded in 2000. It has been funded by the National Science Foundation and the Australian Research Council...