In the image above at left, you can see that there are no nasty, pointy teeth filling this pelycosaur's jaw. You may also see the additional knobs sticking out from the dorsal fin bones, which are unique to the Edaphosauridae. At right, you can see a fully mounted skeleton from the Permian of Texas. The long tail and sprawling posture are characteristic of the pelycosaurs. These images were taken at the Field Museum of Natural History in Chicago.
Pelycosaurs are an important lineage preserved in the fossil record.
They are the earliest known synapsids, the first to evolve specializations that would play an important role in the rise to mammals. They are thus a transitional group in both form and functions. Firstly, no intermediate form represents a totally intermediate character. This is to say that no evolutionary condition has been found in any taxon where all characteristics are present of both taxa that the condition is intermediate to. Secondly, evolutionary transformation predominates in the extremities, and only later affects the axial system.