![\"A](\"https:\/\/images.newscientist.com\/wp-content\/uploads\/2024\/11\/28140421\/SEI_231106509.jpg\")
<\/div>A trackway of footprints thought to have been left by a Paranthropus boisei individual<\/p>\n
Neil T. Roach<\/p>\n<\/div>\n<\/figcaption><\/figure>\n<\/p>\n
Preserved footprints in Kenya appear to record two different species of ancient humans walking over the same muddy lakeshore, probably within days of each other. It is one of the most dramatic demonstrations ever found that the world was once home to multiple hominin species living side by side.<\/p>\n
\u201cIt\u2019s really exceptional that we find this evidence for two different species walking across that surface,\u201d says Kevin Hatala<\/a> at Chatham University in Pittsburgh, Pennsylvania.<\/p>\n The footprints were found in 2021<\/a> in Koobi Fora, Kenya, near the eastern shore of Lake Turkana. They were first spotted by team member Richard Loki at the Turkana Basin Institute<\/a>, says Hatala: \u201cIt was a team of Kenyans who were working there originally.\u201d<\/p>\n Preserved in a dried-out layer of sand and silt, the team found a trackway consisting of 12 footprints (see image, above), evidently left by one individual walking in a straight line. There were also three isolated prints near the main group, seemingly made by three different individuals. The lack of signs of mud cracking or overprinting of tracks with others indicate that the prints were all made at about the same time. \u201cThese sites probably capture a window of time anywhere from minutes to a few days or so,\u201d says Hatala.<\/p>\n <\/p>\n The sediment has been dated to about 1.52 million years ago. The isolated tracks resemble those left by modern humans: the heel struck the ground first, then the foot rolled forwards before pushing off with the sole. Hatala and his colleagues suggest that these were made by Homo erectus<\/em>, which are known to have lived in the area.<\/p>\n In contrast, the continuous trackway was made by a more flat-footed hominin. Hatala and his colleagues suggest this could have been Paranthropus boisei<\/em><\/a>, another kind of hominin that lived in the region.<\/p>\n The fossil footprint on the left with a deeper heel imprint is thought to have been made by a Homo erectus, the more flat-footed one on the right by a Paranthropus boisei<\/p>\n Kevin Hatala\/Chatham<\/p>\n<\/div>\n<\/figcaption><\/figure>\n<\/p>\n \u201cWith footprints, you can never be 100 per cent sure who made them,\u201d says Ashleigh Wiseman<\/a> at University College London, who wasn\u2019t involved in the study. However, H. erectus<\/em> and P. boisei<\/em> are the only hominins whose remains have been found preserved in the area, \u201cso we can make an informed guess that it is those two\u201d.<\/p>\n If the trackway really was made by a P. boisei<\/em> individual, it shows that they walked bipedally, says Wiseman. While skulls, arm and leg bones have been attributed to Paranthropus<\/em>, she says, \u201cwe have never found a skull in association with the rest of the skeleton\u201d. That means we know little about their bodies apart from their heads, and their walking style has been a mystery. The trackway changes that: \u201cIt\u2019s unequivocal evidence of walking on two legs.\u201d<\/p>\n![\"Comparison](\"https:\/\/images.newscientist.com\/wp-content\/uploads\/2024\/11\/28153134\/SEI_231233231.jpg\")
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