Stethacanthus

Stethacanthus

Stethacanthus Fossil range: Late Devonian - Early Carboniferous
A pair of Stethacanthus altonensis
Scientific classification
Order:	Symmoriida
Family:	Stethacanthidae
Genus:	Stethacanthus
Species:	S. altonensis S. productus S. praecursor S. mirabilis S. resistens S. thomasi

Stethacanthus ("Breast spine") is an extinct genus of shark which lived in the Late Devonian and Early Carboniferous epochs, around 360 million years ago. The creature was almost one meter long. It probably hunted smaller creatures such as small fish. Fossils have been found in Europe and North America.

Etymology[]

Stethacanthus comes from the Greek στῆθος (stēthos), meaning "chest", and ἄκανθος (akanthos), meaning "spine" or "thorn". The name refers to the distinctive anvil-shaped first dorsal fin and spine displayed by mature males of the genus.

Description[]

Stethacanthus was around 70 centimeters (2.3 ft) long, and in many respects, hada typical shark-like appearance. However, it is best known for its unusually shaped dorsal fin, which resembled an anvil or ironing board. Small spikes (enlarged versions of the dermal denticles commonly covering shark skin) covered this crest, and the shark's head as well.^[1] Some scientists think the crest may have had a function in courtship; others think it may have been used for self defense.

History[]

The several species of Stethacanthus discovered in the late 1800s were established based solely upon isolated spines, which initially confused paleontologist John Strong Newberry into thinking the spines constituted a new kind of fin. He originally believed that the spines were part of the pectoral fins and that they were not bilaterally symmetrical. Meanwhile, the first associated skeletal remains found in the Mississippian of Montana and the Devonian and Mississippian of Ohio remained undescribed for nearly a century. Since complete skeletons were extremely rare, Stethacanthus classification was vague and based on few characteristics. It was not until 1974 that the family Stethacanthidae was defined by Richard Lund because Stethacanthus differed so greatly from other Elasmobranchs of the time. Relative classifications of symmoriids compared to stethacanthids are still debated. More Stethacanthus specimens have been discovered, expanding their range from the Midwestern United States to the Lower Carboniferous of Bearsden, Scotland and the Lower Tournaisian of the Tula Region of Central Russia and China. Stethacanthus teeth have been recovered from the Frasnian-Famennian Napier Formation and the Tournaisian Laurel Formation and Moogooree Limestone in Western Australia. A partial palate and jawbone referred to a Stethacanthus sp. has also been recovered from the Bonaparte Basin, Western Australia.

Classification[]

References[]

^ Palmer, D., ed (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 27. ISBN 1-84028-152-9.

Haines, Tim & Chambers, Paul. (2006) The Complete Guide to Prehistoric Life. Canada: Firefly Books Ltd.
[1]
http://en.wikipedia.org/wiki/Paleoworld

[EoDP-1] Palmer, D., ed (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 27. ISBN 1-84028-152-9.

[1]