Squalicorax

Squalicorax Temporal range: Cretaceous
Two Squalicorax and a Cretoxyrhina circling around a dead Claosaurus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Order:	Lamniformes
Family:	Anacoracidae Cappetta,1987
Genus:	Squalicorax
Species
See text.

Squalicorax is a genus of extinct lamniform shark known to have lived during the Cretaceous period.

Etymology

The name Squalicorax is derived from the Latin "squalo" for shark and the Greek "corax" for raven.

Description

These sharks are of medium size, up to 5 meters in length (usually smaller - 2 meters). The body were similar to the modern gray sharks, but the shape of the teeth is strikingly similar to that of a tiger shark. The teeth are numerous, relatively small, with a curved crown and serrated, up to 2.5 - 3 cm in height (the only representative of the Mesozoic Lamniformes with teeth). Large numbers of fossil teeth have been found in Europe, North Africa, and other parts of North America.

Squalicorax was a coastal predator, but also scavenged as evidenced by a Squalicorax tooth found embedded in the metatarsal (foot) bone of a terrestrial hadrosaurid dinosaur that most likely died on land and ended up in the water. Other food sources included turtles, mosasaurs, ichthyodectes and other bony fishes and sea creatures.

Description of selected species

Squalicorax pristodontus tooth from the Cretaceous of Morocco.

Squalicorax falcatus

Fossilized vertebrae and pectoral fins of a Squalicorax shark, from Kansas, abt. 70 - 80 mya, at the Smithsonian Institution, Washington

Squalicorax falcatus, Cretaceous lamnoid shark

The following are the best studied American species for which relatively complete skeletons are described:

• Squalicorax falcatus (Agassiz, 1843) – is a medium-sized shark with a broad snout and relatively small teeth. Length reached almost 3 meters. It lived during the Cenomanian - early Santonian (Campanian). Complete skeletons are known from sediments of the Western Inland Sea of the Cretaceous of Kansas, South Dakota and Wyoming. The teeth are also found in France, the Czech Republic, Canada, Morocco. Given the small teeth, this species is considered a hunter of small preys. However, the shark teeth marks on the bones of marine reptiles is evidence that these shark fed on carrion. The body shape and structure of the trunk placoid scales indicate the ability to fast swimming. A fully articulated (fully formed) 1.9 m long fossil skeleton of Squalicorax falcatus has been found in Kansas, evidence of its presence in the Western Interior Seaway.

• Squalicorax kaupi (Agassiz, 1843) - from the late Santonian-late Maastrichtian of North America, New Zealand, Japan, Africa, Europe, Kazakhstan, Jordan and other places. Slightly larger than the preceding species, which probably was the ancestor.

• Squalicorax pristodontus (Agassiz, 1843) – is the largest species, more than 3 - 5 meters long. From the size of its largest known teeth, it can be estimated that Squalicorax pristodontus grew to 5 m (16.5 ft) in length. It lived during the Late Maastrichtian - early Campanian (North America, France, Netherlands, Egypt, Morocco, Madagascar). The relatively complete remains (vertebrae and fragments of jaws) are found in marine sediments in North America. It is a species with the largest teeth. The teeth of this species is rarely planted and relatively very large in comparison with other species. In this genus of sharks the studies showed no precise correlation between the size of the teeth and the length of the body. They could eat relatively large preys and carrions.

• Squalicorax volgensis - the oldest species of the genus, from the Early Cretaceous of the Volga – have been described by L. Glickman et al in 1971. The teeth of this species had virtually no serration. They are known from the Albian - Turonian Eastern and Western Europe, as well as Texas. Teeth have also been found in the Albian of Angola, Australia, the Cenomanian and Santonian of Egypt, Kazakhstan and Russia. Finding the teeth of these sharks in the Cenozoic sediments evidences that genus did not survive the Cretaceous-Paleogene crisis.

List of species

• Squalicorax bassanii Gemmelaro 1920
• Squalicorax curvatus Williston 1900
• Squalicorax dalinkevichiusi (Glikman & Shvazhaite 1971)
• Squalicorax falcatus Agassiz 1843
• Squalicorax kaupi Agassiz 1843
• Squalicorax primaevus (Dalinkevicius 1935)
• Squalicorax primigenius Landemaine 1991
• Squalicorax pristodontus Agassiz 1843
• Squalicorax volgensis Glikman 1971

References

• H. Cappetta, Handbook of Paleoichthyology (Gustav Fischer, 1987)

External links

• Elasmo.com page on Squalicorax
• Cretoxyrhina mantelli - The Ginsu Shark and Squalicorax falcatus - The Crow Shark
• Squalicorax beim ReefQuest Centre for Shark Research