OH 62
OH 62 is the scientific name for the partial fossil skeleton of an adult, presumably female Homo habilis , which was discovered in 1986 by Tim White in Tanzania . The name stands for Olduvai hominid No. 62 , the 62nd prehistoric man discovered in the Olduvai Gorge , who is sometimes referred to as Dik-dik hominid after its location on a hill called Dik Dik Hill . The find was dated to an age of 1.8 million years.
As the first of a total of 302, mostly very small fragments assigned to the fossil, Tim White discovered a piece of the upper bone section of a right ulna on the surface of the earth on July 21, 1986 . The site was 25 meters from the access road to the Olduvai Gorge and only 250 meters southeast of the place where Mary Leakey discovered the first fossil of a "Zinjanthropus" (today: Paranthropus boisei ), the so-called nutcracker man, in 1959 .
After the first bone discovery, the upper layers of the earth were carefully examined over an area of around 40 square meters and a total of around 18,000 fossilized tooth and bone fragments were discovered. With the exception of 302, these remains belonged mainly to small to medium-sized mammals and reptiles, including waterbuck ( Kobus sigmoidalis ), hartebeest and other antelopes , cattle giraffes ( Sivatherium ) and ostriches , crocodiles , frogs and some fish .
The teeth - an important indicator for determining the species - were badly splintered, so that only a few dental crowns of Homo habilis could be completely reconstructed. Nonetheless, it was understandable that the fossil did not have very large molars, so that it lacks one of the typical features of the australopithecines . Also the skull could not be reconstructed due to the lack of sufficiently large remains. However, it was possible to reassemble most of the upper jaw from 32 fragments, which was the decisive factor in interpreting the find as Homo habilis , as it has features, for example, with the skull finds OH 24 and KNM-ER 1813 from Koobi Fora ( Kenya ) and in particular Stw 53 from Sterkfontein shared.
The bone finds from the area below the head were also meaningful: OH 62 was the first fossil of a Homo habilis in which bones of the arms and legs that belonged together were definitely found: most of a right humerus , pieces of ulna and radius as well as one Part of the left femur with shaft and femoral neck. The conclusion that all bones belonged to the same individual arose from the finding that no duplications of bone finds were detected. An analysis of the bone strength and mobility of the humerus showed that it has distinct chimpanzee- like characteristics and deviates significantly from the characteristics of Homo erectus ; From these and other characteristics it was deduced that Homo habilis was able to walk upright, but more often than Homo erectus also stayed in trees.
A comparison of the bone finds with the better preserved skeleton of Lucy - an Australopithecus afarensis - allowed the researchers to estimate the body dimensions of OH 62: the body size was estimated at only 100 centimeters, and the arms were almost as long as the legs; in today's humans, the arms are only 70 percent of the leg length, in today's chimpanzees 100 percent, in OH 62 it was 95 percent. Both the size and the proportions of the limbs were similar to those of the much older Australopithecus afarensis ; Previously, it was believed that Homo habilis was “more modern” in terms of body proportions and, among other things, fossils were assigned to Australopithecus or Homo based on the proportions of their limbs . The small body size was the decisive factor in interpreting the fossil as female. Since the posterior molar (the wisdom tooth ) had already erupted, the fossil was already an adult during its lifetime.
The analysis of the fossil led to the fact that the previously suspected line of development from Australopithecus to Homo habilis to Homo erectus was questioned and today by many researchers Homo rudolfensis is interpreted as the ancestor of Homo erectus .
Stone implements of the Oldowan type discovered in the vicinity of OH 62 could not be assigned to this bone find with sufficient certainty.
In the spring of 2010, Donald Johanson pointed out that the Australopithecus sediba , which had recently been scientifically described for the first time, shares essential characteristics with the fossil OH 62 and that this new find may therefore be more likely to be described as homo .
literature
- Donald C. Johanson et al .: New partial skeleton of Homo habilis from Olduvai Gorge, Tanzania. In: Nature . Volume 327, 1987, pp. 205-209, doi : 10.1038 / 327205a0
- Donald Johanson, Blake Edgar: Lucy and Her Children. Spektrum Akademischer Verlag, Munich 2006, 2nd, updated and expanded edition, p. 188
Web links
Individual evidence
- ↑ Christopher Ruff: Relative limb strength and locomotion in Homo habilis. In: American Journal of Physical Anthropology. Volume 138, No. 1, 2009, pp. 90-100, doi: 10.1002 / ajpa.20907
- ↑ Donald Johanson, Blake Edgar: Lucy and Her Children. Spektrum Akademischer Verlag, Munich 2006, 2nd, updated and expanded edition, p. 188
- ^ Alan Boyle: Fossils Shake Up Our Family Tree ( Memento April 11, 2010 in the Internet Archive ) In: Cosmic Log, msnbc.com.
- ↑ Kate Wong: Discoverer of "Lucy" raises questions about Australopithecus sediba, the new human species from South Africa. ( Memento of April 11, 2010 in the Internet Archive ) On: scientificamerican.com