Edaphosaurus

Skeletal reconstruction of Edaphosaurus Boanerges in New York's American Museum of Natural History

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Edaphosaurus ("patches lizard" to gr edaphos - Paving, floor; sauros - lizard ) is an extinct genus of Pelycosaurier ( Pelycosauria ), the older of the two taxa of the synapsids. Edaphosaurus was one of the first known terrestrial vertebrates ( Tetrapoda ), feeding on plants. The type species is E. pogonias from the Lower Permian of Texas.

Edaphosauridae

The classical nomenclature run as a family Edaphosauriden consisted of only two species, both of which were herbivores ( plant eaters ). Ianthasaurus had a different type of dentition to that of the carnivorous ( meat-eating ) Sphenacodontiden, the most well known Dimetrodon is very similar. Therefore, it is assumed that a sister group relationship between the two genera. The Edaphosauriden were in addition to the Diadectidae, close relatives of the amniotes of the Carboniferous and Permian of Laurussia, the first known herbivores among terrestrial vertebrates.

Morphology

Edaphosaurus resembled in his lizard-like appearance to today's lizards and iguanas, but had shorter legs in proportion. The largest of the approximately nine known species were E. cruciger and E. pogonias, which reached a length of up to 3.2 meters. The fuselage was - typical of a herbivore - barrel-shaped, the unusually small head wide and short, and the tail spine long and thick. The cone-shaped, short and wide teeth were present on both edges of the jaw as well as a large area of ​​the oval areas to the palate and the interior of the lower jaw. The unusual dentition was probably the pluck and crushing of soft plant material.

However, the most striking feature was the enormously elongated spinous processes of the vertebrae of the torso and spine, forming a spectacular and probably over -stressed skin with large " sail". Such sails occurred in three of the six families of Pelycosaurier, but came as convergent evolution also occurs in other tetrapods. Unlike related forms such as Dimetrodon the spinous processes were associated with the Edaphosauriden each other by " cross-ties ". An early finding of a Edaphosaurus described because the connections to the projections on the horizontal spars remind of a ship's mast as originally Naosaurus ( "Ship Six Men ").

Function of Dorsalsegels

The function of the spinal sail at the Pelycosauriern is not fully understood. Discussed are thermoregulation, communication and camouflage, but not necessarily mutually exclusive. Calculations of the importance of the sail in the heat balance show that the heating of the body with more than twice the speed was when the animal in the morning the sails lined up perpendicular to the incident solar radiation. To cool off, Edaphosaurus taught the sail parallel or turned it into the wind. Recent examples of such a strategy for the temperature control can be found in desert lizards. In Edaphosaurus the cross-connections between the spinous processes may improve the heat dissipation of the sail. Wind tunnel tests have shown that the cross-links induced by the turbulence in the air flowing past the thermoregulatory effectiveness of the sail increased, so that the sail could be smaller and shallower than those without. During the mating season the sail may have been conspicuously colored, and played a role in courtship.