Every so often, a discovery comes along that changes our understanding of the distant past. In the vast landscapes of the ...

Some of them, like the giant sloth or the woolly rhino, were generally gentle. Others, like the saber-toothed tiger and the dire wolves, dominated their environment with their size and fearsome fangs.

Archeologists in Mexico have found fossils of extinct animals in a cenote in Umán, Yucatán, including those of a giant sloth ...