The East African Plateau is at least 1,000 meters ( 3,280 ft ) above sea horizontal surface , but millions of geezerhood ago , the area was underwater . Now , harmonize to researchers essay a prehistorical heavyweight fossil unearth at these high raising , the East African Plateau began to rise above ocean tier about 17 million years ago — around the same clock time extremely varying climate and drier conditions began to repel primate ( including human ) evolution . Thesefindingsare published inProceedings of the National Academy of Sciencesthis workweek .
In 1964 , the fossilise skull of a deep - diving , receptive - ocean - living whale was discovered 740 klick ( 460 mile ) inland from the Indian Ocean coastline and at an elevation of 620 meters ( 2,000 ft ) in the Open Pit Turtle Mine of Williams ’ Flat Loperot in West Turkana , Kenya . These Clarence Shepard Day Jr. , the domain is a pretty rough desert ; a photo of the dig is render below to the right . The 17 - million - yr - honest-to-goodness fossil belonged to the old beak whale known ( family Ziphiidae ) , and the only stranded hulk find so far inland on the African continent . But it went missing years later on from the National Museums of Kenya and resurface three decades later on in 2011 at Harvard .
Now , an external team led byHenry Wichura from University of Potsdamexamined the newly rediscovered whale using decennium ’ old playing area notes and phylogenetic analyses , as well as three-D and CT scan . The 7 - meter - long ( 23 foot ) beaked whale in all probability swim eastward from the Indian Ocean along an ancient drainage system call the Anza River , and it believably could n’t change its course , so it kept heading inland for 600 to 900 kilometers ( 370 - 560 stat mi ) . It at long last became stranded at an height slenderly above ocean storey , likely around 24 to 37 time ( 80 - 120 foot ) .
" The giant was stranded up river at a time when East Africa was at ocean level and was covered with forest and jungle , " field of study co - authorLouis Jacobs of Southern Methodist Universitysays in anews release . East Africa 17 million long time ago had a downhearted elevation , high rain and humidness , and was densely vegetated — until activity in Earth ’s mantle pushed the area ( together with the whale ’s fossil ) several hundred meters up . former work with mantle plumes designate that the upthrust of the East African Plateau had already happen by 13.5 million years ago , so now research worker have finally bookended the onset of upheaval .
These plate tectonics ensue in increasingly desiccated and open habitats . " As that part of the continent rose up , that caused the climate to become dryer and drier . So over millions of years , forest gave way to grasslands,”Jacobs tally . “ primate develop to adapt to grasslands and dry country . And that ’s when — in human organic evolution — the primates embark on to walk upright . "
Wichura tell Live Science : " It ’s more or less the chronicle about the bipedalism . ”
Images : Southern Methodist University ( top ) , James G. Mead ( middle ) , H. Wichura et al . , PNAS 2015 ( bottom )
