'Bottom walkers' Recent excavations in Koobi Fora revealed dozens of large animal tracks, dating back to 1.4 million years ago, but a majority of the prints appear to have been left by a four-toed animal "bottom walking" in a shallow water body, study leader Matthew Bennett, of the United Kingdom's Bournemouth University, and his colleagues said.
Because of the size and shape of the prints, the team thinks the tracks could belong to adults and juveniles of the species Hippopotamus gorgops, which went extinct during the Ice Age, and perhaps the pygmy hippo species Hippopotamus aethiopicus.
At the time, the Lake Turkana area was much more fertile than it is today. The semi-arid environment had lots of shallow pools and channels, all feeding into larger lakes, and it supported a striking diversity of plants and animals, Bennett said.
The hippo prints appear to have been pressed into fine sands and silts deposited on the floor of a shallow body of water, before being buried by a layer of coarser sand, likely during a small flood, Bennett explained in an email to Live Science.