In 1974 at the East Turkana site in Kenya, scientists unearthed a small skull fragment that they dated back to 1.9 million years ago and belonged to a Homo erectus. It is the second oldest skull fragment ever found – the title belongs to a specimen found in South Africa that dates back 2 million years.
Since there was so much skepticism regarding the East Turkana skull’s age – they speculated that the bone may have been moved to the location because of water or wind, suggesting that the remains weren’t as old as initially thought – researchers went back to the site and conducted geological surveys.
Dan Palcu, who is a geoscientist at the University of São Paulo and Utrecht University and who coordinated the geological work, explained what they did in further detail, “It was 100 percent detective work.” “Imagine the reinvestigation of a 'cold case' in a detective movie. We had to go through hundreds of pages from old reports and published research, reassessing the initial evidence and searching for new clues. We also had to use satellite data and aerial imagery to find out where the fossils were discovered, recreate the 'scene,' and place it in a larger context to find the right clues for determining the age of the fossils.”
They didn’t find any evidence of younger fossils washing up at the East Turkana site which does support the initial calculation of the skull fragment dating back 1.9 million years. And they made another significant fossil discovery. The researchers found two hominin bones – a partial pelvis and a foot bone.
It’s unclear whether or not these two new specimens came from the same individual whose skull fragment was found because the bones have been separated from each other for many years, but it is possible that they were from the same skeleton. What they do think is that they may be the oldest postcrania specimens (bones found below the head) belonging to a Homo erectus that have ever been found. (A picture of the pelvic bone can be seen here.)
In addition to the Homo erectus bones, the researchers also found several fossilized teeth that belonged to ancient mammals. “Our new carbon isotope data from fossil enamel tell us that the mammals found in association with the Homo fossils in the area were all grazing on grasses,” explained Kevin Uno, who is a paleoecologist at Columbia University's Lamont-Doherty Earth Observatory. Furthermore, the specific Homo erectus whose remains were found was believed to have lived in a paleoenvironment with open areas (instead of forests) and a reliable body of water.
The study was published in the journal Nature Communications where it can be read in full.