Australopithecus sediba transition from the trees to bipedal walking

[shunyadragon]

Source: https://phys.org/news/2021-11-ancient-human-relative-australopithecus-sediba.html

lAncient human relative, Australopithecus sediba, 'walked like a human, but climbed like an ape'


An international team of scientists has discovered a two-million-year-old fossil vertebrae from an extinct species of ancient human relative.

New lower back fossils are the "missing link" that settles a decades old debate proving early hominins used their upper limbs to climb like apes and their lower limbs to walk like humans

An international team of scientists from New York University, the University of the Witwatersrand, and 15 other institutions announced today, in the open access journal e-Life, the discovery of two-million-year-old fossil vertebrae from an extinct species of ancient human relative.

The recovery of new lumbar vertebrae from the lower back of a single individual of the human relative, Australopithecus sediba, and portions of other vertebrae of the same female from Malapa, South Africa, together with previously discovered vertebrae, form one of the most complete lower backs ever discovered in the early hominid record and give insight into how this ancient human relative walked and climbed.

The fossils were discovered in 2015 during excavations of a mining trackway running next to the site of Malapa in the Cradle of Humankind World Heritage Site, just northwest of Johannesburg, South Africa.

Malapa is the site where, in 2008, Professor Lee Berger from the University of the Witwatersrand and his then nine-year old son, Matthew, discovered the first remains of what would be a new species of ancient human relative named Australopithecus sediba.

Fossils from the site have been dated to approximately two million years before present. The vertebrae described in the present study were recovered in a consolidated cement-like rock, known as breccia, in near articulation.




Rather than risking damaging the fossils, they were prepared virtually after scanning with a Micro-CT scanner at the University of the Witwatersrand, thus removing the risk of damaging the closely positioned, delicate bones during manual preparation. Once virtually prepared, the vertebrae were reunited with fossils recovered during earlier work at the site and found to articulate perfectly with the spine of the fossil skeleton, part of the original Type specimens of Australopithecus sediba first described in 2010. The skeleton's catalog number is MH 2, but the researchers have nicknamed the female skeleton "Issa," meaning protector in Swahili. The discovery also established that like humans, sediba had only five lumbar vertebrae.

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[rogue06]

This has long been assumed based on the anatomical structure of the hands and feet but it's nice to have confirmation.

[shunyadragon]

True, but I believe it is based on anatomical comparison with plder tree dwelling primates and other Australopithecus and later hominin primates that evolved arms adapted functionally for more bipedal locomotion.

A believe the evidence is also adaptation from forest to the grassland environment where hominins further evolved,