Dimetrodon and Permian Animals

The Permian period lasted about 47 million years, and it was the first time land animals truly dominated Earth. Before dinosaurs ever existed, therapsids, the group scientists call the "mammal-like reptiles," had already invented features we now think of as mammalian: specialized teeth for chewing, upright posture, and possibly even warm blood. These were not slow, cold-blooded lizards plodding through the mud. Many of them were fast, smart, and fierce.

Permian animals also hold some staggering records. Dimetrodon, the sail-backed predator of the Early Permian, had teeth of two different sizes, something no creature before it had ever evolved. That single trick made it the top predator on land for millions of years. The Permian ended with the worst mass extinction in Earth's history, called the "Great Dying," which wiped out up to 96 percent of all marine species and 70 percent of land species. Understanding Permian animals helps scientists figure out how life survived that catastrophe and eventually gave rise to mammals, and to us.

Dimetrodon is the superstar of the Permian. It lived from about 295 to 272 million years ago, and its iconic back sail could reach over 6 feet tall on large adults. Despite looking like a dinosaur, Dimetrodon was a synapsid, putting it on the evolutionary branch that leads directly to mammals, and eventually to humans. It was about 11 feet long and weighed around 550 pounds, making it the apex predator of its day.

Lystrosaurus is one of the most important survivors in fossil history. This stocky, pig-sized creature with a beak and two short tusks made it through the Great Dying extinction and went on to dominate the Early Triassic landscape. Fossils of Lystrosaurus have been found on every continent including Antarctica, which was powerful early evidence that the continents were once joined as one supercontinent called Pangaea.

Inostrancevia was a gorgonopsian, a group of therapsids built like saber-toothed hunters with canine teeth reaching 5 inches long. At up to 11 feet long, it hunted the large dicynodonts of Late Permian Russia. Moschops was another giant, a barrel-chested plant eater from South Africa that weighed over a ton and may have butted heads like modern bison.

Some of the world's best Permian fossil sites are in places you might not expect. The Karoo Basin of South Africa is the single richest source of Permian and Early Triassic therapsid fossils on Earth. Millions of years of sediment preserved thousands of specimens, and scientists have used Karoo fossils to map out the entire sequence of the Great Dying extinction in incredible detail.

The Texas Red Beds, a series of rust-colored rock formations running through north-central Texas, preserve many of the best-known Early Permian animals including Dimetrodon. Paleontologist Edward Drinker Cope collected the first Dimetrodon skulls there in the 1870s. In Russia, the Malaya Kinel River region of the Ural Mountains has produced spectacular gorgonopsians including Inostrancevia. Russian paleontologist Vladimir Amalitzky excavated the site starting in 1895 and unearthed nearly complete skeletons that shocked the scientific world. Today, casts of those finds are displayed in museums across Europe.