Edaphosaurus

At first glance, Edaphosaurus looks a lot like a scaled-down version of its close relative, Dimetrodon: both of these ancient pelycosaurs (a family of reptiles that preceded the dinosaurs) had large sails running down their backs, which helped to maintain their body temperatures (by radiating away excess heat during the night and absorbing sunlight during the day) and were probably also used to signal the opposite sex for mating purposes.

Oddly enough, though, the evidence points to the late Carboniferous Edaphosaurus having been a herbivore and Dimetrodon a carnivore--which has led some experts (and TV producers) to speculate that Dimetrodon regularly had big, heaping portions of Edaphosaurus for lunch!

Except for its sporty sail (which was much smaller than the comparable structure on Dimetrodon), Edaphosaurus had a distinctly ungainly appearance, with an unusually small head compared to its long, thick, bloated torso. Like its fellow plant-eating pelycosaurs of the late Carboniferous and early Permian periods, Edaphosaurus had a very primitive dental apparatus, meaning that it needed a whole lot of intestines to process and digest the tough vegetation it ate. (For an example of what this "whole lot of guts" body plan can result in, without the distraction of a sail, check out the awkward build of the contemporaneous pelycosaur Casea.)

Given its similarity to Dimetrodon, it's not surprising that Edaphosaurus has generated a fair amount of confusion. This pelycosaur was first described in 1882 by the famous American paleontologist Edward Drinker Cope, after its discovery in Texas; then, a few years later, he erected the closely related genus Naosaurus, based on additional remains excavated elsewhere in the country.

Over the next few decades, however, subsequent experts "synonymized" Naosaurus with Edaphosaurus by naming additional Edaphosaurus species, and even one putative species of Dimetrodon was later moved under the Edaphosaurus umbrella.

Edaphosaurus Essentials

Edaphosaurus (Greek for "ground lizard"); pronounced eh-DAFF-oh-SORE-us

Habitat: Swamps of North America and Western Europe

Historical Period: Late Carboniferous-Early Permian (310-280 million years ago)

Size and Weight: Up to 12 feet long and 600 pounds

Diet: Plants

Distinguishing Characteristics: Long, narrow body; large sail on back; small head with bloated torso