Karoo - Geological History

Geological History

The Great Karoo has an area of more than 400,000 square kilometers. From a geological point of view it has been a vast inland basin for most of the past 250 million years. At one stage the area was glaciated and the evidence for this is found in the widely-distributed Dwyka tillite. Later, at various times, there were great inland deltas, seas, lakes or swamps. Enormous deposits of coal formed and these are one of the pillars of the economy of South Africa today. Ancient reptiles and amphibians prospered in the wet forests and their remains have made the Karoo famous amongst palaeontologists. About 180 million years ago, volcanic activity took place on a titanic scale, which brought an end to a flourishing reptile evolution. The following genera represent some of the extinct animals of the Karoo:

• Mesosaurus, aquatic Dwyka carnivore
• Bradysaurus, Beaufort Group herbivore
• Diictodon, Permian mammal-like reptile
• Rubidgea, Permian predator
• Lystrosaurus, Triassic mammal-like herbivore
• Thrinaxodon, Triassic mammal-like carnivore
• Euparkeria, early dinosaur
• Massospondylus, late Triassic to early Jurassic herbivorous, bipedal dinosaur
• Megazostrodon, early mammal

The first Karoo fossils were discovered in 1838 by Scots-born Andrew Geddes Bain at a road cutting near Fort Beaufort. He sent his specimens to the British Museum, where fellow Scotsman Robert Broom recognised the Karoo fossils' mammal-like characteristics in 1897.