''Kaprosuchus'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of mahajangasuchid

crocodyliform 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 ...

. It is known from a single nearly complete skull collected from the

Upper Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', th ...

Echkar Formation The Echkar Formation is a geological formation comprising sandstones and claystones in the Agadez Region of Niger, central Africa. Description Its strata date back to the Late Albian to Late Cretaceous ( Cenomanian stages, about 100-95 milli ...

Niger ) , official_languages = , languages_type = National languagesGreek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

, ''kapros'' ("boar") and , ''soukhos'' ("crocodile") in reference to its unusually large caniniform teeth which resemble those of a

boar The wild boar (''Sus scrofa''), also known as the wild swine, common wild pig, Eurasian wild pig, or simply wild pig, is a suid native to much of Eurasia and North Africa, and has been introduced to the Americas and Oceania. The species is ...

. It has been nicknamed "BoarCroc" by

Paul Sereno Paul Callistus Sereno (born October 11, 1957) is a professor of paleontology at the University of Chicago and a National Geographic "explorer-in-residence" who has discovered several new dinosaur species on several continents, including at sites ...

and Hans Larsson, who first described the genus in a monograph published in ''

ZooKeys ''ZooKeys'' is a peer-reviewed open access scientific journal covering zoological taxonomy, phylogeny, and biogeography. It was established in 2008 and the editor-in-chief is Terry Erwin (Smithsonian Institution). It is published by Pensoft P ...

'' in 2009 along with other Saharan crocodyliformes such as ''

Anatosuchus ''Anatosuchus'' ("duck crocodile", the name from the Latin ''anas'' ("duck") and the Greek ''souchos'' ("crocodile"), for the broad, duck-like snout) is an extinct genus of notosuchian crocodylomorph discovered in Gadoufaoua, Niger, and described ...

'' and ''

Laganosuchus ''Laganosuchus'' is an extinct genus of stomatosuchid crocodyliform. Fossils have been found from Niger and Morocco and date back to the Upper Cretaceous. Discovery The name means "pancake crocodile" from the Greek , ("pancake") and , ("cro ...

''. 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 specime ...

is ''K. saharicus''.

Description

''Kaprosuchus'' is known from a nearly complete skull 507 mm in length in which the lower jaw measured 603 mm long. The original description estimated the entire animal to be in length,National Geographic. November 2009. p. 140-141 although newer estimates lowered this to around 4 meters (13.1 ft). It possesses three sets of tusk-like caniniform teeth that project above and below the skull, one of which in the lower jaw fits into notches in upper jaw. This type of dentition is not seen in any other known crocodyliform. Another unique characteristic of ''Kaprosuchus'' is the presence of large, rugose horns formed from the

squamosal The squamosal is a skull bone found in most reptiles, amphibians, and birds. In fishes, it is also called the pterotic bone. In most tetrapods, the squamosal and quadratojugal bones form the cheek series of the skull. The bone forms an ancestral co ...

and

parietal bone The parietal bones () are two bones in the skull which, when joined at a fibrous joint, form the sides and roof of the cranium. In humans, each bone is roughly quadrilateral in form, and has two surfaces, four borders, and four angles. It is nam ...

s that project posteriorly from the skull. Smaller projections are also seen in the closely related ''

Mahajangasuchus ''Mahajangasuchus'' is an extinct genus of crocodyliform which had blunt, conical teeth. The type species, ''M. insignis'', lived during the Late Cretaceous; its fossils have been found in the Maevarano Formation in northern Madagascar. It was a ...

''. The snout of ''Kaprosuchus'' shows generalized proportions and the naris is positioned dorsally. In ''Kaprosuchus'' many teeth are

hypertrophied Hypertrophy is the increase in the volume of an organ or tissue due to the enlargement of its component cells. It is distinguished from hyperplasia, in which the cells remain approximately the same size but increase in number.Updated by Linda J ...

and labiolingually (laterally) compressed, unlike those of crocodyliforms with similarly shallow snouts, which are usually subconical and of moderate length. Another difference between the skull of ''Kaprosuchus'' and those of crocodyliforms that also possess dorsoventrally compressed snouts is the great depth of the posterior portion of the skull. In ''Kaprosuchus'', the

orbits In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a p ...

(i.e., eye sockets) open laterally and are angled slightly forward rather than upward. The orbits turned forward suggest that there was somewhat

stereoscopic vision Stereopsis () is the component of depth perception retrieved through binocular vision. Stereopsis is not the only contributor to depth perception, but it is a major one. Binocular vision happens because each eye receives a different image becaus ...

, i.e., an overlap in the visual field of the animal. The surfaces of 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 ...

e are rugose with the edges elevated above the body of the bone, suggesting that a

keratinous Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin (α-keratin) is a type of keratin found in vertebrates. It is the key structural material making up scales, hair, nails, feathers, ho ...

shield would have been supported by the rugosities at the tip of the snout. Along the interpremaxillary suture, the area where the two premaxillae meet, the surface is smooth, giving the paired rugosity of the premaxillae the resemblance of a moustache in anterior view.

Classification

''Kaprosuchus'' is a member of the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Mahajangasuchidae along with closely related ''Mahajangasuchus insignis'' from the Upper Cretaceous of

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

. Although it differs greatly from any other known crocodyliform, ''Kaprosuchus'' shares several characteristics with ''Mahajangasuchus''. These include the obliteration of all but the posterior portion of the

internasal suture 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 ...

; a laterally facing rugose external articular fossa; the positioning of the jaw joint below the posterior

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. T ...

ry teeth; a deep, anterodorsally oriented mandibular symphysis; a vertically descending ectopterygoid that is slightly inset from the lateral margin of the

jugal The jugal is a skull bone found in most reptiles, amphibians and birds. In mammals, the jugal is often called the malar or zygomatic. It is connected to the quadratojugal and maxilla, as well as other bones, which may vary by species. Anatomy ...

; a flared

choana The choanae (singular choana), posterior nasal apertures or internal nostrils are two openings found at the back of the nasal passage between the nasal cavity and the throat in tetrapods, including humans and other mammals (as well as crocodilia ...

l septum forming an articular foot for the

palatine A palatine or palatinus (in Latin; plural ''palatini''; cf. derivative spellings below) is a high-level official attached to imperial or royal courts in Europe since Roman times.

; and the hornlike dorsal projection of the external rim of the squamosal (although this is much more developed in ''Kaprosuchus'' than ''Mahajangasuchus''). At the time of ''Kaprosuchus description, Sereno and Larrson considered mahajangasuchids to be a family of

Neosuchian Neosuchia is a clade within Mesoeucrocodylia that includes all modern extant crocodilians and their closest fossil relatives. It is defined as the most inclusive clade containing all crocodylomorphs more closely related to ''Crocodylus nilotic ...

crocodyliforms. However further studies on the relationship of this family have repeatedly found them to form a sister clade to

peirosaurids Peirosauridae is a Gondwanan family of mesoeucrocodylians that lived during the Cretaceous period. It was a clade of terrestrial crocodyliforms that evolved a rather dog-like form, and were terrestrial carnivores. It was phylogenetically defined ...

, forming a clade that in turn groups together with

uruguaysuchids Uruguaysuchidae is a family of notosuchian crocodyliforms that lived in South America and Africa during the Cretaceous period. It includes the genera ''Araripesuchus ''Araripesuchus'' is a genus of extinct crocodyliform that existed during the ...

such as ''Anatosuchus'' and ''Araripesuchus'' as an early diverging branch of

notosuchians Notosuchia is a suborder of primarily Gondwanan mesoeucrocodylian crocodylomorphs that lived during the Jurassic and Cretaceous. Some phylogenies recover Sebecosuchia as a clade within Notosuchia, others as a sister group (see below); if S ...

Paleobiology

Diet

''Kaprosuchus'' is thought to have been a primarily if not exclusively terrestrial predator. Evidence for this behavior includes the positioning of the orbits laterally and somewhat anteriorly, which suggests an overlap in vision. This is unlike many other neosuchians, including extant crocodilians, in which the orbits are positioned dorsally as an adaptation to aquatic predation where the head can be held underwater while the eyes remain above the surface. Additional support for terrestrial predation can be found in the teeth and jaws. The enlarged caniniforms are sharp-edged and relatively straight, unlike the fluted, subconical, recurved teeth of aquatic crocodyliforms. Because the retroarticular process of the lower jaw is long, it is likely that the jaws were able to open relatively quickly with a large gape to allow for the opposing caniniforms to clear one another. The fused nasal bones are thought to have provided reinforcement for the jaws against compression associated with a powerful bite. The telescoped, dorsally positioned external nares are seen as protection against impact if the animal rammed prey with its robust snout. The keratinous shield thought to have covered the tip of the snout would have provided further protection.

References

External links

''Kaprosuchus''
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=Q137176 Terrestrial crocodylomorphs Late Cretaceous crocodylomorphs of Africa Fossil taxa described in 2009 Notosuchians Prehistoric pseudosuchian genera Cenomanian genera