The footprints were left in the mud by two different species “within a matter of hours, or at most days,” a co-author of the research study said.

Researchers discovered 1.5-million-year-old footprints in Kenya's Turkana Basin, revealing coexistence of Paranthropus boisei and Homo erectus. The prints, showing distinct walking patterns, provide direct evidence of the two species' interaction and environment,

About 1.5 million years ago, individuals of two different species in the human evolutionary lineage trudged on a muddy lakeshore in northern Kenya, leaving behind intersecting trackways alongside the footprints of antelopes,