Gorgonopsia




 * Class Therapsida
 * Clade Theriodontia
 * Order †Gorgonopsia
 * Subfamily †Gorgonopsinae
 * Subfamily †Ailurapodamiminae
 * Family †Dinoceratopsidae
 * Family †Ursamimidae
 * Family †Pseudopantheridae

Gorgonopsids first evolved in the Guadalupian epoch and soon outcompeted the carnivorous dinocephalians as the top predators of their environment. The earliest gorgonopsids, like †Kamagorgon, were small, no bigger than a dog, but they soon grew to much larger sizes with the extinction of predatory dinocephalians. They soon become the apex predators of the environments they lived in. Much like the dinocephalian predators that dominated the Guadalupian, such as †Titanophoneus, gorgonopsids had “sabre teeth”, elongated and narrow upper canines that were probably used to cut open the windpipe of their prey. They also lacked useful teeth behind their canines and had no ability to chew. It is likely they simply tore pieces of flesh off of the carcass and swallowed them whole. Most gorgonopsids in the Upper Permian were around two metres in length, but some like †Inostrancevia and †Rubidgea could be almost four metres. Gorgonopsid success was hardly, if at all, affected by the minor extinction at the end the Permian. Throughout the Triassic and Jurassic eras, gorgonopsids thrived and continued to diversify. From the Induan to the Anisian, they remained virtually identical to species from the late Permian, however they soon started to evolve more advanced teeth. Several well preserved fossils of the species †Cucumipellis from Argentina dating to the Carnian epoch suggest that most gorgonopsids at this time had tough, hairless skin with small bumps resembling a cucumber. A fragmentary skull of an unnamed species from Australia shows that by the Rhaetian some gorgonopsids had evolved whiskers which †Cucumipellis is known to have lacked. Gorgonopsids in the Triassic also do not seem to have grown to the sizes they did in the Permian due to the dense rainforests that covered most of the world not allowing room for large animals, and most of them seem to have been arboreal to an extent. During the Jurassic, gorgonopsids started to become much more diverse and evolved some of the strangest forms of any animal throughout history. Species like the multi horned †Dinoceratops, the five meter long †Basilocerops, and the pot-bellied herbivorous †Ailurapodamimus all evolved to cope with the changing environment of the Jurassic. It is thought that gorgonopsids first evolved a full covering of fur sometime in the Jurassic despite the oldest furry gorgonopsid fossils being from the early Cretaceous. Oddly, despite the Jurassic being the time when gorgonopsids were at their most diverse, it was also the time when the range of gorgonopsids was reduced. Unlike cynodonts and therocephalians, gorgonopsids had difficulty adapting to the temperate forests that appeared in the Aalenian. However, they were still very successful as predators of newly formed mountain ranges and cold deserts, where they started to grow to massive sizes, culminating in the evolution of †Basilocerops, the largest gorgonopsid to have ever lived. Gorgonopsids also became predators of the Polar Regions, which still lacked ice caps, and some even evolved toward an herbivorous diet. The gorgonopsid “golden age” ended with another climate change at the end of the Jurassic. The herbivorous gorgonopsid radiation ended in the Berriasian partly due to climate change, which gorgonopsids due not seem to deal with well as a whole, and partly due to the evolution of more efficient herbivores. In the Cretaceous, the remaining gorgonopsids became increasingly mammal-like, including evolving external ears. They became less specialized and more generalist in diet, several becoming omnivorous. Most species evolved thick fur to deal with the gradually cooling climate. Their teeth also became more adapted to cracking bones and armour (likely due to the evolution of armoured archosaurian herbivores as well as armoured dicynodonts). The gorgonopsids were quite successful still until the Santonian when the number of species lowered and surviving species became rarer, coinciding with the numerous ice ages and warming periods that occurred in the last eighteen million years of the Cretaceous. There were very few species left by the Campanian. A single species, †Cryopanthera orientalis, managed to hold on in Siberia during the Maastrichtian Ice Age. One vertebra that could belong to this species has been suggested by some to prove that this last gorgonopsid survived for a short time into the Paleocene epoch. Although the time this species went extinct is still the subject of fierce debate, all agree that gorgonopsids were extinct by the beginning of the Eocene. Exactly why gorgonopsids went extinct is still a mystery, the general theory being that it was due to a combination of climate change, competition from more successful predators, and prey that was difficult for gorgonopsids to hunt. The fact that they were the only theriodont group that never evolved the ability to chew could also have played a part in its extinction.