In 2009, scientists discovered eight bones from the foot of an ancient human ancestor inside layers of million-year-old sediment within the Afar Rift in Ethiopia. The crew, led by Arizona State University paleoanthropologist Yohannes Haile-Selassie, didn’t assign a species to the three.4-million-year-old fossil — till now.
The fossil, known as the Burtele Foot, was discovered at the Woranso-Mille paleontological site and was introduced in a 2012 Nature article.
“When we found the foot in 2009 and announced it in 2012, we knew that it was different from Lucy’s species, Australopithecus afarensis, which is widely known from that time,” mentioned Haile-Selassie, director of the Institute of Human Origins and professor on the School of Human Evolution and Social Change.
“However, it is not common practice in our field to name a species based on postcranial elements — meaning elements below the neck — so we were hoping that we would find something above the neck in clear association with the foot. Crania, jaws and teeth are usually the elements used in species recognition.”
When the Burtele Foot was introduced, some enamel were already discovered from the identical space, however the scientists were not satisfied the enamel were from the identical degree of sediments. Then, in 2015, the crew introduced a brand new species, Australopithecus deyiremeda, from the identical space — however were not in a position to conclusively embody the foot into this species although a few of the specimens were discovered very near the foot, Haile-Selassie says.
Now, after 10 years of going again into the sphere and persevering with to search out extra fossils, Haile-Selassie mentioned they’ve specimens that they’ll confidently affiliate with the Burtele Foot and with the species A. deyiremeda.
What’s in a reputation — and a foot?
The task of the Burtele Foot to a species is simply a part of the story.
The website of Woranso-Mille is critical as a result of it’s the solely website the place scientists have clear proof displaying two associated hominin species co-existed on the identical time in the identical space, defined Haile-Selassie.
The Burtele Foot, belonging to A. deyiremeda, is extra primitive than the ft of Lucy’s species, A. afarensis. The Burtele Foot retained an opposable massive toe, which is necessary for climbing, and the toes were longer and extra versatile — additionally appropriate for climbing.
But when A. deyiremeda walked on two legs, it probably pushed off on its second digit quite than its massive toe like we trendy people do right this moment.
“The presence of an abducted big toe in Ardipithecus ramidus was a big surprise because at 4.4 million years ago, there was still an early hominin ancestor which retained an opposable big toe, which was totally unexpected,” Haile-Selassie mentioned.
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What teeth tell us
To get insight into the diet of A. deyiremeda, Naomi Levin, a professor at the University of Michigan, sampled eight of the 25 teeth found at the Burtele areas for isotope analysis. The process involves cleaning the teeth, making sure to only sample the enamel and using very tiny tools like today’s dentists use.
“I sample the tooth with a dental drill and a very tiny (
The results were surprising.
While Lucy’s species was a mixed feeder, eating C3 resources (from trees and shrubs) and C4 plants (tropical grasses and sedges), A. deyiremeda was utilizing mostly C3 resources.
“I was surprised that the carbon isotope signal was so clear and so similar to the carbon isotope data from the older hominins A. ramidus and Australopithecus anamensis,” she mentioned. “I thought the distinctions between the diet of A. deyiremeda and A. afarensis would be harder to identify, but the isotope data show clearly that A. deyiremeda wasn’t accessing the same range of resources as A. afarensis, which is the earliest hominin shown to make use of C4 grass-based food resources.”
More clues from jaws
Along with the 25 enamel discovered at Burtele, scientists additionally discovered the jaw of a juvenile, which primarily based on the anatomy of the enamel clearly belonged to A. deyiremeda.
This jaw had a full set of child enamel already in place, but in addition had plenty of grownup enamel creating deep down inside the bony mandible, says Gary Schwartz, Institute of Human Origins research scientist and professor on the School of Human Evolution and Social Change.
The crew used state-of-the-art micro-CT scanning expertise to have a look at all the creating enamel as a result of there’s a shut connection between each the sample and tempo of tooth improvement with a species’ general progress biology. This allowed the scientists to estimate that this jaw belonged to a hominin that was round 4.5 years outdated when it died.
“For a juvenile hominin of this age, we were able to see clear traces of a disconnect in growth between the front teeth (incisors) and the back chewing teeth (molars), much like is seen in living apes and in other early australopiths, like Lucy’s species,” Schwartz mentioned.
“I think the biggest surprise was despite our growing awareness of how diverse these early australopith (early hominin) species were — in their size, in their diet, in their locomotor repertoires and in their anatomy — these early australopiths seem to be remarkably similar in the manner in which they grew up.”
Knowing how these ancient ancestors moved and what they ate supplies scientists with new data about how species coexisted on the identical time with out one pushing the opposite to extinction.
“All of our research to understand past ecosystems from millions of years ago is not just about curiosity or figuring out where we came from,” Haile-Selassie said. “It is our eagerness to learn about our present and the future as well.”
“If we don’t understand our past, we can’t fully understand the present or our future. What happened in the past, we see it happening today,” he said. “In a lot of ways, the climate change that we see today has happened so many times during the times of Lucy and A. deyiremeda. What we learn from that time could actually help us mitigate some of the worst outcomes of climate change today.”
The paper, “New finds shed light on diet and locomotion in Australopithecus deyiremeda,” was revealed within the journal Nature. Funding for this challenge was offered by the National Science Foundation and the W.M. Keck Foundation. Field and laboratory research in Ethiopia was facilitated by the Ethiopian Heritage Authority.