The footprints discovered byMary Leakeyand her squad at Laetoli , Tanzania are some of the creation ’s most illustrious . Their discovery in 1978 revealed that hominins , possibly our direct ancestors , had walk upright 3.66 million years ago . Nearby , the Leakey survey also observe another set of footprints in 1976 , but the recognition of these was less certain , leave them to descend into neglect . Now , anthropologists have returned to the equivocal photographic print , found at Laetoli Site A , and found they prove two bipedal hominin species once lived in skinny proximity .
An astonishing 18,000 animal print have been feel in the volcanic ash tree at Laetoli Site A , but involvement centers on five clear made by an animate being walk on its hind leg . Mary Leakey proposed they were made by a hominin . Other members of the team , however , thought they could be from a bear walk just , and were loth to make a fuss about something so uncertain . When the univocal , and now renowned , print were found at Laetoli Site G , with a subsequent find at site S , Laetoli A prints were largely forgotten .
“ Given the increasing grounds for locomotor and species diversity in the hominin fossil record over the retiring 30 years , these unusual print deserved another look , ” first authorDr Ellison McNuttof Ohio University said in astatement . McNutt is part of a bombastic team that used Leakey ’s record to re - name the prints and 3D scan them .
The generator then tempt four semi - wild American black bears untried enough their prints fit in sizing those at Site A , with maple sirup to take the air bipedally across mud . The prints were so different that , even allow for the fact an ancient Tanzanian bear would have been from another species the authors are confident no member of genusUrsusmade the prints at Laetoli Site A.
“ [ bear ] are unable to take the air with a pace similar to that of the Site A footprints , as their hip musculature and knee joint form does not permit that kind of motion and balance,”Dr Jeremy DeSilvaof Dartmouth said . Moreover , although bear can walk on two legs , they do so only occasionally , so bipedal prints are strange . standardized psychoanalysis rein out near relatives of chimpanzee .
The print show a crown of thorns - whole tone in a way humans do n’t when moving freely , but resemble those of a person struggling to keep their footing on uneven ground .
extra print from the Almighty of the Laetoli G tracks would have some value , but the two do n’t match . Instead , Site A ’s track shaper was smaller and had feet shaped otherwise enough to be another metal money .
“ The footprints at site A are preserved in the same ash level as the path made at situation G and S , mean that they were made within ( at most ) days of one another , but more probable hr or mo , ” DeSilva state IFLScience . “ These two hominins were contemporaries on the landscape painting . ”
The Laetoli Site G prints have long been associate withAustralopithecus afarensis , include the famousLucyfossil , and the generator do n’t challenge that .
“ The foot bones fromA. afarensismatch the footprint at sites G and S much well than they match the prints at site A , ” DeSilva told IFLScience . “ In this paleoanthropological version of Cinderella , the challenge now will be to discover which hominin groundwork accommodate the slipper [ of Laetoli A ] . ” DeSilva suggestedKenyanthropus platyopsandAustralopithecus deyiremedaas candidates .
