Pelycosauria

From Palaeos.org

o Amniota
|--Sauropsida
`--o SYNAPSIDA
   `==Pelycosauria
      `==Therapsida
         `==Mammaliaformes
            `--Mammalia 

The Early Permian apex predator Dimetrodon grandis. (Eupelycosauria, Sphenacodontia, Sphenacodontidae)

Introduction

The pelycosaurs (from Greek pelyx meaning 'bowl' and sauros meaning 'lizard') were smallish to large (up to 3 meters or more) primitive Late Paleozoic synapsid amniotes. They appeared during the Late Carboniferous and reached their acme in the early part of the Permian Period, remaining the dominant land animals for many millions of years. A few stragglers continued into the late Permian.

Well-known pelycosaurs include the genera Dimetrodon, Sphenacodon, Edaphosaurus, and Ophiacodon.

The traditional Pelycosauria is paraphyletic with regard to the Therapsida.

o Amniota
`--o PELYCOSAURIA
   |--Caseasauria
   `--o--Varanopseidae
      `--o--Ophiacodontidae
         `--o--Edaphosauridae
            `--o--Haptodus
               `--o--Palaeohatteria
                  `--o--Pantelosaurus
                     `--o--Cutleria
                        `--o--Sphenacodontidae
                           `--+?-Tetraceratops
                              `-- THERAPSIDA

Information

Stratigraphic range: Late Carboniferous - Late Permian

Linnaean taxonomy:

• Phylum: Chordata
  • Superclass: Tetrapoda
    • Class: Reptilia (classic definition)
      • Subclass: Synapsida (made a class in Benton 2000, 2004)
        • Order: Pelycosauria

Author: Cope, 1878

Environment: Semi-aquatic, terrestrial water margins, some forms may have lived in more upland environments

Ecology and Evolution

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 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.

Credits