The world's greatest fossil graveyard
South Africa's Karoo Supergroup is a vast geological formation covering almost two-thirds of the country. It represents a nearly continuous 120-million-year record of Earth's history, from the late Carboniferous (around 300 million years ago) to the Early Jurassic (around 180 million years ago). The layers of shale and sandstone, which reach a cumulative thickness of up to 12 kilometers in some places, were deposited in a vast inland sea and the successive terrestrial environments that replaced it. This sequence of rock holds one of the most complete records of terrestrial life during the Permian and Triassic periods, making it the world's most significant collecting ground for fossils of our distant ancestors: the therapsids.
Therapsids are a group of synapsids, often called "mammal-like reptiles," that represent the evolutionary transition between reptiles and true mammals. They flourished during the Permian Period, diversifying into a wide array of forms that filled ecological niches much like modern mammals. Some were large, tusked herbivores like the Dicynodonts, which had tortoise-like beaks. Others were terrifying predators. The Dinocephalians ("terrible heads") were among the first large land animals, reaching 3 meters in length with extraordinarily thick skulls. The Gorgonopsians were tiger-sized apex predators, characterized by enormous saber-like canine teeth. The most mammal-like of all were the Cynodonts ("dog teeth"), the group that gave rise to all mammals around 225 million years ago.