Edaphosaurus. They're three-meters-long, as big as hippos, and like them, they're vegetarians. Amazingly, these strange sail-backs are related to us.
— Allen, on Edaphosaurus

Edaphosaurus ("Pavement Lizard") is a genus of early sailed-back pelycosaur, or sail-back mammal-like reptiles, that originated during the Early Permian period. It was the first plant-eating reptiles to evolve.


Era & DiscoveryEdit

Edaphosaurus lived during the Early Permian period 280-260 million years ago. It was first discovered by Edward Drinker Cope in 1882.

Physical AttributesEdit

Edaphosaurus were giant, sail back mammal-like reptilian animals that basked in the early morning sun. They grew to measure three meters in length, were the size of hippos, and like them, Edaphosaurus were also vegetarians. Edaphosaurus was blue with yellow stripes. Its sail had an eye-shaped pattern on it.

Thanks to the huge sails on their back, their back bone had tall spines connected by a thin membrane of blood-filled skin. This large surface area could lose heat fast if the Edaphosaurus needed to cool down. While to heat up, they simply turned their sails towards the sun like a solar panel. Amazingly, these strange sail-backs are related to humans. It's down to them that we have control over our body temperature today.

Similar to the dinosaur Stegosaurus, Edaphosaurus could flush blood into their sails to distract predators from their vulnerable heads. With warmer weather, the Edaphosaurus lazed beneath conifers, shading their sails from the sun to avoid overheating.

To grind down these tough mouthfuls, Edaphosaurus developed a specialized jaw and teeth. They were some of the first creatures with this adaptation. Digesting plants is a more challenging task than meat and the Edaphosaurus vasts stomach acts as a no-stop processing factory.

Behavior & TraitsEdit

Like many herbivores, Edaphosaurus also lived in huge herds from tens to hundreds of individuals. In these large groups, they nurtured and protected their offspring. Adult Edaphosaurus were practically invulnerable due to their size, and even Dimetrodon preferred to hunt juveniles instead. These creatures also often fed on the thriving conifers.

When the hot, mid-day sun rises, herds of Edaphosaurus laid beneath the conifers to digest and also carefully shades their sails from the heat. When summer arrived, Edaphosaurus thrived in the heat. The young that had grown tested out their new-found strength.

Journal EntryEdit

Strange sail-back mammal-like reptiles, Edaphosaurus often basked in the early morning sun. Measuring 3 meters in length, these herbivores were as big as hippos and were also vegetarians. It seems that if Edaphosaurus need to warm up, they turn their sails towards the sun but if they need to cool down, the large surface area on their tall spines connected by a thin membrane of blood-filled skin looses heat.

It turns out that in a similar way to the Stegosaurus, in order to protect their vulnerable heads, Edaphosaurus were able to flush blood into their sails as a distraction to predators. The females also nurtured and protected their offspring, which were easy targets for predators, since they were more vulnerable to attack than the adults.

— Allen, in his Journal, about Edaphosaurus