The most ancient discoveries in Gannat, ancestors of the rhinoceros from the end of the Oligocene and start of the Miocene, date back 23 million years. Gannat seems to have been a veritable cemetery for these creatures, so many of their remains have been discovered. Also found are fossils of fish, reptiles, tortoises, crocodiles, galliform birds, mammals, marsupials, insectivores, rodents and carnivores. The site is particularly rich in rhinoceros. From 1854, Duvernoy has even described a specimen as "Acerotherium gannatense" (the official name is "Diaceratherium lemanense"). The most complete rhinoceros skeleton was discovered in 1993 when significant fossils were uncovered at the Sichaux quarry by paleontologist François Escuillié (notable discoverer of a small proboscidian mammal, ancestor of the elephant from 50 million years ago). Escuillié was behind the establishment of the Rhinopolis Association in 1994 and founder of Eldonia, a society for those specialising in the renovation of fossils and whose activities are linked to Rhinopolis. The Rhinopolis Association is still active in the Gannat quarries and, since the 1990s, has discovered numerous rhinoceros bones.