The discovery of new Australopithecus sediba vertebrae offers new information on this species

A silhouette of Australopithecus sediba showing the available bones with the vertebrae and their 3D reconstruction
An article published in the journal “eLife” reports a study of Australopithecus sediba’s spine. A team of researchers created 3D reproductions of fossil vertebrae discovered in 2015 during excavations at the Malapa site, where the first bones attributed to this hominin species were discovered. This allowed obtaining an almost complete lower spine of the specimen cataloged as MH2 whose characteristics confirm the conclusions of previous studies that indicated that these australopithecines used their arms to climb trees like apes but used their legs in bipedal walking like the later species of the genus Homo.

The first bones of Australopithecus sediba were discovered on August 15, 2008, when Professor Lee Berger was excavating the Malapa natural reserve with his son Matthew, who discovered the first fossil bone attributed to this species. Some incomplete skeletons were assembled by putting together the bones discovered over time and immediately the characteristics in part similar to humans and in part similar to apes were noted. An in-depth description was published in six articles in the journal “Science” in April 2013.

The female cataloged as MH2 was nicknamed Issa, which means protector in the Swahili language. Additional bones were discovered in 2015 at the same site and the vertebrae matched Issa’s vertebrae already available. The task was complex because the researchers didn’t want to risk damaging the fossils, so they created a 3D reproduction by subjecting them to a micro-CT scan.

The top image (Courtesy NYU & Wits University. All rights reserved) shows a silhouette of Australopithecus sediba showing the available bones with the vertebrae and their 3D reconstruction. The bottom image (Courtesy NYU & Wits University. All rights reserved) shows another silhouette of Australopithecus sediba that highlights the vertebrae and shows the anatomical features that allowed this species to live in trees.

Professor Scott Williams, the first author of the article, explained that the lumbar region is critical for understanding the nature of bipedalism in our earliest ancestors and to understand how adapted they were to walk on two legs. A series of lumbar vertebrae from the same specimen are extraordinarily rare, and only three have been found among any of the oldest African fossils.

Vertebrae found in early excavations led researchers to speculate that Australopithecus sediba walked on its legs and had arms and trunk adapted to life in trees. It’s a mix of characteristics typical of earlier hominin species and apes and others that have become an important part of later species and the genus Homo. The new vertebrae confirmed this hypothesis even though Issa’s spine resembles those of Neanderthals and other early hominins more than that of modern humans.

Australopithecus sediba is considered to be a close relative of modern humans who lived about 2 million years ago. That’s another reason why the study of its anatomical characteristics is important and the discovery of other vertebrae offers new information on the transition that led to the emergence of bipedal hominins, a crucial moment in the history of humanity.

A silhouette of Australopithecus sediba that highlights the vertebrae and shows the anatomical features that allowed this species to live in trees

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