ZoomDinosaurs.com Dinosaur and Paleontology Dictionary

PELYCOSAURS

Pelycosaurs (meaning "basin lizards") were the earliest, and most primitive synapsids; they were not dinosaurs. These quadrupeds appeared during the upper Carboniferous and went extinct during the Permian period (before the Triassic period when the dinosaurs evolved). Pelycosaurs began as small, lizard-like animals and evolved into larger, more differentiated types. Some were carnivores, some were herbivores; some had sailbacks like Dimetrodon, some did not. These swamp dwellers had a sprawling gait and were likely the ancestors of the therapsids, which led to the mammals.

Pelycosaurs are divided in to the

• Suborder Eupelycosauria
  • Family Varanopseidea
  • Family Ophaicodontidae (very primitive, e.g., Varanosaurus, Ophiacodon)
  • Family Ophiacodon, Edaphosauridae (e.g., Edaphosaurus, Dimetrodon)
  • Family Sphenacodontidae (large with a deep, narrow skull and specialized teeth, e.g., Sphenacodon)
• Suborder Caseasauria
  • Family Eothyrididae (primitive, leading to the Caseidae)
  • Family Caseidae (medium to large herbivores and the only line to continue along to mammals, e.g., Casea).

Some Pelycosaurs:

DIMETRODON (pronounced die-MET-roh-don) Dimetrodon was a prehistoric animal with a large sail; it was not a dinosaur but a pelycosaur, an early synapsids.

EDAPHOSAURUS (pronounced ah-DAFF-oh-SAWR-us) Edaphosaurus (meaning "ship lizard") was an herbivorous early synapsid that lived during the late Carboniferous and early Permian periods, about 320 to 258 million years ago, long before the dinosaurs existed. This pelycosaur (early synapsids) was related to Dimetrodon and had long spines growing out of its backbone. These spines had distinctive crossbars on them and may have been covered by skin, forming a thermoregulatory sail. This quadruped was about 11 feet (3.2 m) long and weighed about 660 pounds (300 kg), had a small head, large eyes, a barrel-shaped body, and a long tail. It lived in wet areas (in swamps and near lakes) and ate rough plant material that it could crush with its flat teeth. Its fossils have been found in Europe and North America.

VARANOSAURUS (pronounced vahr-AN-oh-SAWR-us) Varanosaurus was a mammal-like reptile (not a dinosaur). This pelycosaur looked like a modern-day monitor lizard. Varanosaurus grew to be about 5 ft (1.5 m) long. It was an amniote that walked on four sprawling (five-toed) legs, had a long tail, a deep, narrow skull, and a long jaw with many small, sharp, curved, flattened teeth. It probably ate fish. This extinct, early synapsid was a dead-end in the mammalian lineage, closely related to Ophiacodon, and also Dimetrodon and Edaphosaurus. Varanosaurus lived during the early Permian in what is now Texas and Oklahoma, USA. Classification: Order Pelycosauria: Suborder Eupelycosauria: Family Ophiacodontidae: Genus Varanosaurus.

CASEA Casea was a small, sail-less pelycosaur from the early Permian period. It looked like a fat lizard; it had 4 short, sprawling legs, a long tail, a small head, a bulky body, a huge rib cage, and a large gut (needed to digest its food). This plant-eater ate tough plants, like horsetails and ferns. It had no teeth in its lower jaw, but had thick, peg-like teeth in the upper jaw. It also had small teeth on the palate itself (the roof of the mouth). Casea was about 4 feet (1.2 m) and may have weighed over 1,300 pounds (600 kg). Fossils of this synapsid have been found in France and the USA (Texas).

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