The enigmatic Edaphosaurus, aka the "pavement lizard," will not be tread on! Like many other prehistoric critters, there were several species of Edaphosaurus that spanned across multiple geologic periods: from the Carboniferous to the Permian. The largest species could grow to an impressive three meters long! Despite sporting a similar sail to the Permian predator Dimetrodon, Edaphosaurus was actually a gentle herbivore. The name "pavement lizard" refers to its densely-packed teeth, which sat in deep jaws that sported mighty muscles. Ferns must have quivered with fear when they saw the formidable Edaphosaurus appear! During the Carboniferous, Edaphosaurus lived in iconic rainforests called coal forests (named for the fact that its plant matter became coal). The species that lived in the Permian period still inhabited lush marshes, but experienced gradual global warming and drying as the planet transitioned to hot, dry deserts. Although some researchers hypothesized that its large sail was useful for cooling the body, it was likely used for either fat storage or display instead. The "pavement lizard" paraded its sail across a large range, extending across much of the modern United States, only vulnerable to falling prey to large predators like Dimetrodon.