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Dimetrodon

2007 Schools Wikipedia Selection. Related subjects: Dinosaurs

             iDimetrodon

                         Fossil range: Late Permian

   Dimetrodon grandis skeleton at the National Museum of Natural History
   Dimetrodon grandis skeleton at the
   National Museum of Natural History
                         Scientific classification

   Kingdom: Animalia
   Phylum:  Chordata
   Class:   Synapsida
   Order:   Pelycosauria
   Family:  Sphenacodontidae
   Genus:   Dimetrodon
            Cope, 1878

                                   Species

     * D. milleri
     * D. natalis
     * D. limbatus
     * D. booneorum
     * D. gigashomogenes
     * D. grandis
     * D. loomisi
     * D. angelensis
     * D. teutonis

   Dimetrodon (/daɪˈme.tɹəʊˌdɒn/) was a predatory synapsid (' mammal-like
   reptile') genus that flourished during the Permian Period, living
   between 280 and 260 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 Centre of the Earth. Fossils of Dimetrodon
   have been found in North America and Europe. The climate of Europe and
   North America in the Early Permian, was probably arid to continental,
   so Dimetrodon was probably adaptable.

Characteristics

   Dimetrodon was a dominant carnivore, the largest known of its day. It
   grew to up to 3 meters (10 feet) in length. The name Dimetrodon means
   'two-measure 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. The sail was probably used to regulate body
   temperature; the surface area would allow it to warm up or cool off
   more efficiently. In this way, it could have easily picked off slower
   prey that was still warming up. 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.

Relationship with modern mammals

   As a synapsid, Dimetrodon was distantly related to humans and all other
   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. For more information on human
   ancestry, see timeline of human evolution.

In popular culture

   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 thus attributing them to Dimetrodon is an almost
   entirely speculative move on the part of the originators, who have
   presented the characteristics as 'fact', rather than speculation, in
   order to heighten the sense of realism.

   Dimetrodon is often mistaken for Spinosaurus, due to the fact that they
   both had 'sails'. Spinosaurus however, was a dinosaur and bipedal,
   whereas Dimetrodon was not a dinosaur and was quadrupedal.
     * Dimetrodon appeared in the film Journey to the Centre of the Earth.
     * In Power Rangers: Dino Thunder, one of Black Ranger's zords was a
       Dimetrodon.
     * Dimetrodon is often included in dinosaur toy sets, despite the fact
       that it was not a dinosaur.
     * In Dinosaucers, the character Dimetro is an anthropomorphic
       Dimetrodon.
     * Dimetrodon made an appearance in The Land Before Time (1988).

   Artist's impression of Dimetrodon.
   Enlarge
   Artist's impression of Dimetrodon.

   Retrieved from " http://en.wikipedia.org/wiki/Dimetrodon"
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   with only minor checks and changes (see www.wikipedia.org for details
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