Two ancient human ancestors' "crossed paths" are revealed by fossil footprints.

Individuals of two distinct species in the evolutionary tree of humans trekked along a muddy lakeside in northern Kenya approximately 1.5 million years ago. Along with the footprints of antelopes, horses, warthogs, huge storks, and other animals, members of two distinct species in the human evolutionary branch trekked across a muddy lakeside in northern Kenya approximately 1.5 million years ago. These tracks intersected. These footprints evolved into fossils, which researchers have now found at a site known as Koobi Fora. This is the first ...