Pelycosaur facts for kids

Quick facts for kids Pelycosaurs Temporal range: Upper Carboniferous – Upper Permian
Dimetrodon grandis skeleton at the National Museum of Natural History
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Superclass:	Tetrapoda
Class:	Synapsida
Order:	Pelycosauria * Cope, 1878
Suborders
Caseasauria Eupelycosauria

Pelycosaurs (say "PEL-ih-koh-sors") were some of the very first animals that looked a bit like reptiles. Their name means "basin lizards." They were not actually dinosaurs or true reptiles. Instead, they were early synapsids. Synapsids are a group of animals that eventually led to mammals, like us!

These amazing creatures lived on land. They first appeared about 320 million years ago, during the Pennsylvanian period. For about 40 million years, Pelycosaurs were the main land animals. Most of them died out during a huge event called the P/Tr extinction event at the end of the Permian period. However, a few survived into the early Triassic period. These survivors evolved into a new group called therapsids, which were the ancestors of all mammals.

What Pelycosaurs Looked Like

Pelycosaur fossils have been found mostly in Europe and North America. Some smaller, later Pelycosaurs have also been found in Russia and South Africa.

The Famous Back Sail

Many Pelycosaurs had a very tall "sail" on their backs. This sail was made of long bones that stuck up from their spine. It would have been covered by skin. Two main groups of Pelycosaurs, the edaphosaurids and the sphenacodontids, developed these sails.

Scientists think these sails might have helped the animals control their body temperature. They could have used the sail to warm up in the sun or cool down in the shade. The sails might also have been used to attract mates, like a colorful display.

Skin and Scales

Unlike modern reptiles, Pelycosaurs did not have scales all over their bodies. Fossils show that some parts of their skin were smooth. However, their bellies were covered in tough plates called scutes. These scutes looked a bit like reptile scales, but they were built differently.

Well-Known Pelycosaurs

Some of the most famous Pelycosaurs include:

• Dimetrodon: This one is well-known for its large back sail and sharp teeth.
• Edaphosaurus: Another Pelycosaur with a sail, but its sail had cross-bars.
• Sphenacodon: This Pelycosaur was related to Dimetrodon but did not have a sail.
• Ophiacodon: These Pelycosaurs had long, narrow skulls and likely lived near water.

Pelycosaur Family Tree

Scientists group Pelycosaurs into different families based on their features. Here is a simplified look at their family tree:

• Order †Pelycosauria
  • Suborder †Caseasauria
    • Family †Caseidae
    • Family †Eothyrididae
  • Suborder †Eupelycosauria
    • Family †Edaphosauridae
    • Family †Haplodontidae
    • Family †Lupeosauridae
    • Family †Ophiacodontidae
    • Family †Sphenacodontidae
    • Family †Varanopseidae
• Order †Therapsida

Images for kids

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  Comparison of "pelycosaurian" skulls: 1 sphenacodont, 2 ophiacodont, 3 caseid. The quadratojugale is green, squamosale is red, jugale is blue.

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  Cotylorhynchus (background), Ophiacodon and Varanops

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  Eothyris

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  Cotylorhynchus – a caseid

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  Dimetrodon – a sphenacodontid

See also

In Spanish: Pelicosaurios para niños