In South Africa, the Karoo region is full of fossils of therapsids, the ancestors of the mammals that ruled the world long before the dinosaurs appeared. A team from the University of Witwatersand set off in search of these fascinating rocks, which hold the secrets of the extraordinary reptiles known as therapsids. Divided into six families, they vie for the crown of king of the Karoo… but only one of them will survive to give birth to our lineage.