Hidden in barrels and loaded on trucks, thousands of limestone slabs were set to be smuggled out of Brazil in 2013. Taken from a quarry in the country’s renowned Araripe Basin, these were no ordinary rocks. They contained preserved remains and impeccable imprints of creatures that lived millions of years ago.

Bound to be sold to museums and potentially private collectors around the world, the fossil bounty would have fetched its poachers thousands of dollars, if not more. Instead, police raids that were part of an investigation codenamed Operation Munich intercepted the illegal export and sent nearly 3,000 of the seized specimens to the University of São Paulo.

Among the relics was a bizarre winged reptile, nearly four feet tall