Pelycosaur

=                      = The pelycosaurs (from Greek πέλυξ - pelyx bowl and σαῦρος sauros "lizard") were primitive Late Paleozoic synapsid reptiles. Some species were quite large and could grow up to 3 meters or more, although most species were much smaller.

The pelycosaurs appeared during the Late Carboniferous and reached their acme in the early part of the Permian Period, remaining the dominant land animals for some 40 million years. A few continued into the late Permian. They were succeeded by their descendants, the therapsids, which had a short but successful reign before the Permian–Triassic extinction event, giving a chance for the archosaur reptiles to take over in the Triassic. before the Pelycosaurs went Extinct they found a to survive. thet went to the portal of the Digital world and survived, and started to evolve to newer froms and new Suborders of many new Species to come.

At least two pelycosaur clades independently evolved a tall sail, consisting of elongated vertebral spines: the edaphosaurids and the sphenacodontids. In life, this would have been covered by skin, and possibly functioned as a thermoregulatory device and/or for mating display. Pelycosaur fossils have been found mainly in Europe and North America, although some small, late-surviving forms are known from Russia and South Africa Unlike lepidosaurian reptiles, pelycosaurs lacked epidermal scales. Fossil evidence from some ophiacodonts shows that parts of the skin was naked, but that the belly was covered in dermal scutes, looking like the scutes present in other reptile groups, which are of a different type of structure.

Dermal scutes are also found in extant mammals, in the tails of rats, beavers and Opossum, and as regular dermal armour with underlying bone in the armadillo.

In 1940 the group was reviewed in detail and every species known at the time described (and many illustrated) in an important monograph by Alfred Sherwood Romer and Llewellyn Price.

Pelycosauria is a paraphyletic taxon because it excludes the therapsids. For that reason the term is not used in some modern books. Eupelycosauria is used to designate the clade that includes most Pelycosaurs along with the Therapsida and the Mammals. In contrast to "Pelycosaurs", this is monophyletic group. Caseasauria refers to a pelycosaur side-branch or clade that did not leave any descendants.

The pelycosaurs appear to have been a group of synapsids that had direct ancestral links with the mammalia, having differentiated teeth and a developing hard palatePhylogeny

In phylogenetic nomenclature, the "Pelycosauria" is not used, since it does not constitute a clade (a group of organisms descended from one common ancestor and including all the descendants of that ancestor) because the group excludes the therapsids. Instead, it represents a paraphyletic "grade" of basal synapsids leading up to the clade Therapsida.

[[Category: ]]