Skip to comments.Ardi's kind had a skull fit for a hominid
Posted on 05/18/2013 4:32:07 PM PDT by SunkenCiv
One of the most controversial proposed members of the human evolutionary family, considered an ancient ape by some skeptical scientists, is the real hominid deal, an analysis of a newly reconstructed skull base finds.
By 4.4 million years ago, Ardipithecus ramidus already possessed a relatively short, broad skull base with a forward-placed opening for the spinal cord, an arrangement exclusive to ancient hominids and people today, William Kimbel of Arizona State University in Tempe reported on April 11 at the American Association of Physical Anthropologists annual meeting.
Although features of the skull's floor evolved substantially in Homo species leading to modern humans, Kimbel said, those changes appeared in piecemeal fashion starting at least a couple of million years earlier in hominids such as Ardipithecus...
By examining 79 skull bases of chimps, gorillas, modern humans and ancient hominids, Kimbel's group identified relationships among anatomical landmarks that distinguish apes from people and hominids. The researchers estimated the total length of A. ramidus' skull bottom and found that it fell within a range characteristic of hominids, not apes...
A new 3-D analysis of Ardi's previously reconstructed pelvis, also presented April 11 at the anthropology meeting, finds a mix of monkey, ape and hominid characteristics. Although not confirming a consistently upright gait, this version of Ardi's hips doesn't undermine her proposed hominid status, said Nicole Webb of City University of New York, who led the research.
(Excerpt) Read more at sciencenews.org ...
Organic material may be oldest example of human skin
News in Brief: American Association of Physical Anthropologists meeting
Highlights from the annual physical anthropology meeting, Knoxville, April 10-13
By Bruce Bower
Web edition: April 15, 2013
Print edition: May 18, 2013; Vol.183 #10 (p. 13)
The earliest preserved swatch of hominid skin may have been found by discoverers of South African fossils assigned to a nearly 2-million-year-old species called Australopithecus sediba, a possible precursor of the Homo genus. Reddish brown material on the skull of an A. sediba boy shows provocative similarities to human skin, Rachelle Keeling of the University of the Witwatersrand in Johannesburg reported on April 11.
Microscopic analyses of the substance revealed irregular lines resembling blood vessels, as well as depressions characteristic of fat pockets and hair follicles. Chemical tests confirmed that the stuff is organic and has a molecular structure like that previously found in the skin of mummified human bodies.
A. sediba individuals fell into an underground cave where their bodies were quickly covered by soil in a dry place free of predators, making the preservation of skin possible, Keeling said. Further tests are planned to verify that the ancient boy is the world’s oldest skin head.
News in Brief: Possible human ancestor in Australopithecus sediba
The hominid’s unusual build may place it in humankind’s lineage
By Bruce Bower
Web edition: April 11, 2013
Print edition: May 4, 2013; Vol.183 #9 (p. 20)
BONES OF CONTENTION
A reconstruction of the curious-looking hominid Australopithecus sediba shows an unusual mosaic of body characteristics that may make it a direct human ancestor.
L. Berger, Univ. of Witwatersrand
A surprising mix of apelike and humanlike features from head to toe supports a controversial contention that a 2-million-year-old member of the human evolutionary family gave rise to the genus Homo, an international team of researchers reports in six papers published April 12 in Science.
Anthropologist Lee Berger of the University of the Witwatersrand in Johannesburg, South Africa, and his colleagues assigned two partial skeletons and other fossils found in a South African cave in 2008 to a species they named Australopithecus sediba. Among the group’s new findings: A. sediba’s teeth suggest that this hominid evolved into a Homo species but had no links to earlier East African hominids often regarded as Homo ancestors. Those hominids include 3.2-million-year-old Australopithecus afarensis, best known for Lucy’s partial skeleton. A. sediba’s relatively long arms were suited to hanging out in trees, consistent with its narrow, apelike upper rib cage. But these hominids also had narrow, humanlike lower rib cages and lower backs that were longer and more flexible than those of people today. A. sediba probably walked awkwardly with its feet rolling inward and slightly pigeon-toed.
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Thanks for this, eh? Fascinating stuff!
No, but your post is.
"More fragments were recovered in 1994, amounting to 45% of the total skeleton.
This fossil was originally described as a species of Australopithecus, but White and his colleagues later published a note in the same journal renaming the fossil under a new genus, Ardipithecus.
"Between 1999 and 2003, a multidisciplinary team led by Sileshi Semaw discovered bones and teeth of nine A. ramidus individuals at As Duma in the Gona Western Margin of Ethiopia's Afar Region.
The fossils were dated to between 4.35 and 4.45 million years old."
This sounds like at least three different discoveries in two separate locations.
Map of the fossil sites of the earliest hominids (35.8-3.3M BP):
I think all th eArdi parts were found at one spot. Given the conditions at the site and of the fragments of bones how would anyone know what was being represented.
It appears the fragments were “reconstructed” until they fit together.
A couple of comments on the discovery:
“It was the find of a lifetime. But the teams excitement was tempered
by the skeletons terrible condition. The bones literally crumbled when
touched. White called it road kill. And parts of the skeleton had been
trampled and scattered into more than 100 fragments; the skull was
crushed to 4 centimeters in height. The researchers decided to remove
entire blocks of sediment, covering the blocks in plaster and moving
them to the National Museum of
Ethiopia in Addis Ababa to finish
excavating the fossils.
It took three field seasons to
uncover and extract the skeleton,
repeatedly crawling the site to
gather 100% of the fossils present.
At last count, the team had
cataloged more than 110 specimens
of Ar. ramidus, not to mention
150,000 specimens of fossil
plants and animals.
National Geographic put it thus:
After Ardi died, her remains apparently were trampled down into mud by hippos and other passing herbivores. Millions of years later, erosion brought the badly crushed and distorted bones back to the surface. They were so fragile they would turn to dust at a touch.
“Chalky”? “Squished”? “Badly crushed and distorted”? “Needed extensive digital reconstruction”? After all the media hype and overblown claims about importance of Ida, forgive me for having an initial reaction of skepticism. How far would you trust a “Rosetta stone” that was initially “crushed to smithereens” and “would turn to dust at a touch”?
Claims of bipedalism often depend upon precise measurements of the angles of key bones such as the pelvis, femur, and knee-bones. But if these bones were discovered in such a crushed, squished, etc. form, determining the precise contours of these bones might become a highly subjective exercise. I’m sure they spent a lot of time on their reconstructions (and it certainly sounds like they did) but at the end of the day, it’s difficult to make solid claims about extremely unsolid bones.
Anyone for some Irish stew?
As I read it, there were two different species of Ardipithecus -- ramadus (4.4 million years) and kadabba (5.6 million years) -- discovered in at least three different locations, and including at least eleven individuals.
Here (on left) are some of the ramadus bones and (on right) kadabba:
No doubt you are correct in pointing out there's plenty of room for error or different interpretations.
These don't particularly concern me, because in due time new fossils will likely be found, to help confirm or correct whatever is interpreted about these particular bones.
It's how science works.