Dimetrodon

Dimetrodon Fossil range: Early Permian
Restoration of Dimetrodon
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Synapsida Order: Pelycosauria Family: Sphenacodontidae Genus: Dimetrodon Cope, 1878
Species
D. angelensis D. booneorum D. giganhomogenes D. grandis D. limbatus D. loomisi D. macrospondylus D. milleri D. natalis D. occidentalis D. teutonis

Dimetrodon grandis skeleton at the
National Museum of Natural History

Dimetrodon (/daɪˈmɛ.tɹəʊˌdɒn/) ("two measures of teeth"), was a predatory synapsid (\'mammal-like reptile\') genus that flourished during the Permian Period, living between 280 and 265 million years ago. It was more closely related to mammals than to true reptiles (Sauropsida), like dinosaurs, lizards and birds.

Dimetrodon was not a dinosaur, despite being popularly grouped with them. Rather, it is classified as a pelycosaur. It is surprisingly well-known to the general public and makes an appearance in the James Mason film Journey to the Center of the Earth, as well as in Yor, the Hunter from the Future. Fossils of Dimetrodon have been found in North America and Europe, as well as a significant discovery of Dimetrodon footprints in southern New Mexico by Jerry MacDonald. The climate of Europe and North America in the Early Permian, was probably arid to continental, so Dimetrodon was probably adaptable.^{[citation needed]}

Description

Dimetrodon was an apex predator, among the largest of its day. It grew to up to 3 1/2 meters (11 feet) in length. The name Dimetrodon means \'two-measures of teeth\', so named because it had a large skull with two different types of teeth (shearing teeth and sharp canine teeth), unlike reptiles. Dentition showing this differentiation of teeth is called heterodonty. It walked on four side-sprawling legs and had a large tail. Dimetrodon may have moved in a manner similar to present-day lizards.

Sail

The most distinctive characteristic of Dimetrodon was the spectacular sail on its back (another pelycosaur, Edaphosaurus, also has this trait). The sail was probably used to regulate body temperature; the surface area would allow it to warm up or cool off more efficiently. This adaptation was important because it would give the animal more time to hunt prey. The sail may also have been used in mating rituals and to warn off other predators. The sail was supported by neural spines, each one sprouting from an individual vertebra. Bramwell and Fellgett (1973) calculate that a 200 kg Dimetrodon would heat up from 26° C to 32° C in 205 minutes without a sail and in only 80 minutes with a sail.Bramwell, C. D.; Fellgett, P.P. (1973). "Thermal regulation in sail lizards". Nature 242: 203-205. Retrieved on 2007-03-29. 

Relationship with modern mammals

As a synapsid, Dimetrodon was distantly related to modern mammals. Synapsids were the first tetrapods to evolve differentiated (or heterodont) teeth. Whereas reptiles hardly chew their food, simply gulping it down, synapsids like Dimetrodon developed teeth to help shear meat into smaller pieces for easier ingestion. These \'two-measure teeth\' eventually gave rise to the various kinds of teeth present in modern mammals.

In popular culture

In many popular culture references, Dimetrodon is often erroneously seen as a dinosaur or as living alongside dinosaurs.

A composite of Edaphosaurus and Dimetrodon fossilsBoth came from Permian strata in Texas. went on display in 1907 in the American Museum of Natural History, New York, presented by the curator of vertebrate paleontology Henry Fairfield Osborn and illustrated in the pages of Scientific American (May 1907) as "Naosaurus", by the great scientific illustrator Charles R. Knight.

Dimetrodon was one of several prehistoric animals seen in the Rite of Spring segment of Disney\'s Fantasia, where it is shown as an intermediate predator, preying upon Nothosaurus but fleeing from a Tyrannosaurus.

In the television documentary Walking With Monsters (called Before the Dinosaurs in the U.S.), baby Dimetrodon were shown hatching with sails, fully independent. In fact, no Dimetrodon eggs have yet been found and it\'s entirely possible that the sail, which would be hard to store in an egg, was either absent or not rigid upon hatching. The program also stated that Dimetrodon consumed 90% of a carcass, while lions today eat 70% and that Dimetrodon would only eat intestines after shaking out the waste inside, since "dung is one thing a Dimetrodon can\'t stomach." Hatchlings also had to sprint towards trees after hatching in order to escape cannibalistic adults. These behaviours seem to be based on the Komodo Dragon and attributing them to Dimetrodon is entirely speculative. Dimetrodon was also shown as having an egg-laying style similar to the modern crocodile, burying eggs in mounds of sand, adding or removing sand when needed.

It will appear in Primeval series 3.

Gallery

See also

• Edaphosaurus
• Haptodus
• Sphenacodon
• List of apex predators
• Permian

References

This article is licensed under the GNU Free Documentation License. It uses material from Wikipedia