Kaprosuchus
Encyclopedia
Kaprosuchus is an extinct genus
of mahajangasuchid
crocodyliform. It is known from a single nearly complete skull collected from the Upper Cretaceous Echkar Formation of Niger
. The name means "boar crocodile" from the Greek
kapros ("boar") and souchos ("crocodile") in reference to its unusually large caniniform teeth which resemble those of a boar
. It has been nicknamed "BoarCroc" by Paul Sereno
and Hans Larsson, who first described the genus in a monograph published in ZooKeys
in 2009 along with other Saharan crocodyliformes such as Anatosuchus
and Laganosuchus
. The type species
is K. saharicus.
and parietal bone
s that project posteriorly from the skull. Smaller projections are also seen in the closely related Mahajangasuchus
.
The snout of Kaprosuchus shows generalized proportions and the naris is positioned dorsally. In Kaprosuchus many teeth are hypertrophied
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
(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, i.e., an overlap in the visual field of the animal.
The surfaces of the premaxilla
e are rugose with the edges elevated above the body of the bone, suggesting that a keratinous 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.
Mahajangasuchidae along with closely related Mahajangasuchus insignis from the Upper Cretaceous of Madagascar
. 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; a laterally facing rugose external articular fossa; the positioning of the jaw joint below the posterior maxilla
ry teeth; a deep, anterodorsally oriented mandibular symphysis; a vertically descending ectopterygoid that is slightly inset from the lateral margin of the jugal
; a flared choana
l septum forming an articular foot for the palatine
; and the hornlike dorsal projection of the external rim of the squamosal (although this is much more developed in Kaprosuchus than Mahajangasuchus).
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.
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 mahajangasuchid
Mahajangasuchidae
Mahajangasuchidae is an extinct family of neosuchian crocodyliforms. It currently contains two genera, Mahajangasuchus and Kaprosuchus, both of which lived during the Late Cretaceous in Gondwana...
crocodyliform. It is known from a single nearly complete skull collected from the Upper Cretaceous Echkar Formation of Niger
Niger
Niger , officially named the Republic of Niger, is a landlocked country in Western Africa, named after the Niger River. It borders Nigeria and Benin to the south, Burkina Faso and Mali to the west, Algeria and Libya to the north and Chad to the east...
. The name means "boar crocodile" from the Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
kapros ("boar") and souchos ("crocodile") in reference to its unusually large caniniform teeth which resemble those of a boar
Boar
Wild boar, also wild pig, is a species of the pig genus Sus, part of the biological family Suidae. The species includes many subspecies. It is the wild ancestor of the domestic pig, an animal with which it freely hybridises...
. It has been nicknamed "BoarCroc" by Paul Sereno
Paul Sereno
Paul Callistus Sereno is an American paleontologist from the University of Chicago who discovered several new dinosaur species on several continents. He has conducted excavations at sites as varied as Inner Mongolia, Argentina, Morocco, and Niger...
and Hans Larsson, who first described the genus in a monograph published in ZooKeys
ZooKeys
ZooKeys is a peer-reviewed open access academic journal for the field of zoology. It was established in 2008, and the editor-in-chief is Terry Erwin from the Smithsonian Institution...
in 2009 along with other Saharan crocodyliformes such as Anatosuchus
Anatosuchus
Anatosuchus is an extinct genus of notosuchian crocodylomorph discovered in Gadoufaoua, Niger, and described by a team of palaeontologists led by the American Paul Sereno in 2003, in the Journal of Vertebrate Paleontology...
and Laganosuchus
Laganosuchus
Laganosuchus is an extinct genus of stomatosuchid crocodyliform. Fossils have been found from Niger and Morocco and date back to the Upper Cretaceous. The name means "pancake crocodile" from the Greek laganon and souchos in reference to the shallow depth of the skull, which is characteristic of...
. 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 K. saharicus.
Description
Kaprosuchus is estimated to have been around 6 metres (20 feet) in length. 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 squamosalSquamosal
The squamosal is a bone of the head of higher vertebrates. It is the principal component of the cheek region in the skull, lying below the temporal series and otic notch and bounded anteriorly by postorbital. Posteriorly, the squamosal articulates with the posterior elements of the palatal complex,...
and parietal bone
Parietal bone
The parietal bones are bones in the human skull which, when joined together, form the sides and roof of the cranium. Each bone is roughly quadrilateral in form, and has two surfaces, four borders, and four angles. It is named from the Latin pariet-, wall....
s that project posteriorly from the skull. Smaller projections are also seen in the closely related Mahajangasuchus
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.Sereno et al....
.
The snout of Kaprosuchus shows generalized proportions and the naris is positioned dorsally. In Kaprosuchus many teeth are hypertrophied
Hypertrophy
Hypertrophy is the increase in the volume of an organ or tissue due to the enlargement of its component cells. It should be distinguished from hyperplasia, in which the cells remain approximately the same size but increase in number...
and labiolingually
Commonly used terms of relationship and comparison in dentistry
There are numerous commonly used terms of relationship and comparison that refer to different aspects of teeth and are frequently utilized in articles about dentistry...
(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
Orbit (anatomy)
In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents...
(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, i.e., an overlap in the visual field of the animal.
The surfaces of 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 are rugose with the edges elevated above the body of the bone, suggesting that a keratinous 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 familyFamily (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Mahajangasuchidae along with closely related Mahajangasuchus insignis from the Upper Cretaceous of Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of 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; a laterally facing rugose external articular fossa; the positioning of the jaw joint below the posterior 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...
ry teeth; a deep, anterodorsally oriented mandibular symphysis; a vertically descending ectopterygoid that is slightly inset from the lateral margin of the jugal
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....
; a flared choana
Choana
Choana is the posterior nasal aperture.The choanae are separated by the vomer.- Boundaries :It is the opening between the nasal cavity and the nasopharynx....
l septum forming an articular foot for the palatine
Palatine bone
The palatine bone is a bone in many species of the animal kingdom, commonly termed the palatum .-Human anatomy:...
; and the hornlike dorsal projection of the external rim of the squamosal (although this is much more developed in Kaprosuchus than Mahajangasuchus).
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.
External links
- ZooBank
- Kaprosuchus in the Paleobiology DatabasePaleobiology 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...