Hybodus

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Hybodus
Temporal range: 260–74.8Ma
Late Permian to Late Cretaceous
Hybodus fraasi.jpg
Hybodus fraasi in the Museum für Naturkunde in Berlin
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Superorder: Selachimorpha
Order: Hybodontiformes
Superfamily: Hybodontoidea
Family: Hybodontidae
Genus: Hybodus
Agassiz, 1837
Species

See text for species.

Hybodus ("humped tooth") is an extinct genus of once-common, widespread and long lived sharks, first appearing towards the end of the Permian period, and disappearing during the Late Cretaceous. During the Triassic, Jurassic, and Cretaceous periods the hybodonts were especially successful and could be found in shallow seas across the world. For reasons that are not fully understood, the hybodonts became extinct near the end of the Late Cretaceous period.

Description[edit]

Restoration of H. fraasi
Hybodus hauffianus

Hybodus species grew to about 2 metres (6.6 ft) in length, and are believed to have been opportunist predators. It was not very big, but had the classic streamlined shark shape, complete with two dorsal fins that would have helped it steer with precision. The mouth was not large, and rather than ruthlessly hunt large prey, Hybodus, was capable of eating a wide range of foods. They had several distinct features that made them stand apart from other primitive sharks. Firstly, they had two different types of teeth, suggesting a wide diet. The sharper teeth would have been used to catch slippery prey, while the flatter teeth probably helped them crush shelled creatures. Secondly, they had a bony blade on their dorsal fin that probably served a defensive function. The males also possessed claspers, specialized organs that directly insert sperm into the female, and which are still present in modern sharks.[1]

The youngest Hybodus fossils come from the Dinosaur Park Formation. They date from 76.6 to 74.8 million years ago.[2]

The first fossilized teeth from Hybodus were found in England around 1845. Since then teeth (and dorsal spines) have been recovered from around the world.

Species[edit]

Several Hybodus species, including H. butleri, H. rajkovichi, and H. montanensis, were later reassigned to Meristodonoides.[3]

  • Hybodus houtienensis
  •  ?Hybodus butleri
  •  ?Hybodus obtusus
  •  ?Hybodus parvidens
  •  ?Hybodus rajkovichi
  •  ?Hybodus montanensis

In popular culture[edit]

Hybodus was featured in the third episode of the popular 1999 documentary series Walking with Dinosaurs, being attracted to the blood of an Ophthalmosaurus in labor. It was unidentified in this episode. Hybodus made its return in the 2003 spin-off Sea Monsters, it was shown feeding on a giant struggling Leedsichthys with Metriorhynchus. Hybodus' name was heard by Nigel Marven's voice when he saw a Hybodus shark attacking a Leedsichthys.

In 2004, the children's book "Jurassic Shark" by Deborah Diffily and colorfully illustrated by Karen Carr highlights a pregnant female Hybodus shark battling a Liopleurodon and hunting ichthyosaurs.

References[edit]

  1. ^ Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 28. ISBN 1-84028-152-9. 
  2. ^ Neuman, A.G. & Brinkman, D.B. (2005). "Fishes of the fluvial beds". In Currie, P.J. & Koppelhus, E.B. Dinosaur Provincial Park: A Spectacular Ancient Ecosystem Revealed. Bloomington and Indianapolis: Indiana University Press. pp. 167–185. ISBN 0-253-34595-2. 
  3. ^ Underwood, Stephen L.; Cumbaa (July 2010). "Chondrichthyans from a Cenomanian (Late Cretaceous) bonebed, Saskatchewan, Canada". Palaeontology 53 (4): 903–944. doi:10.1111/j.1475-4983.2010.00969.x. 

Haines, Tim, and Paul Chambers. The Complete Guide to Prehistoric Life. Pg. 89. Canada: Firefly Books Ltd., 2006.

Diffily, Deborah and Karen Carr. Jurassic Shark. HarperCollins Publishers, Byron Preiss, 2004.