name = "Ardipithecus"
image_caption = "Ardipithecus kadabba" fossils
phylum = Chordata
genus = "Ardipithecus"
genus_authority = White et al., 1995
subdivision = †"
"Ardipithecus" is a very early hominin
genus( subfamily Homininae) which lived about 4.4 million years ago during the early Pliocene.
Because this genus shares several traits with the African
great apegenera (genus "Pan" and genus " Gorilla"), it is considered by some to be on the chimpanzeerather than humanbranch, but most consider it a proto-humanbecause of a likeness in teeth with " Australopithecus".
specieshave been described, "Ardipithecus ramidus" and "Ardipithecus kadabba", which was initially described as a subspeciesof "A. ramidus", but on the basis of teeth recently discovered in Ethiopiahas been raised to species rank. Remains from both species have been found in the Middle Awash.
"A. ramidus" was named in September 1994. The first fossil find was dated to 4.4 million years ago based on its interval between two volcanic strata: the basal Gaala Tuff Complex (GATC) and the Daam Aatu Basaltic Tuff (DABT). Subsequent fossil discoveries by
Yohannes Haile-Selassieand Giday WoldeGabriel—if identified as "A. ramidus"—would push the date back as far as 5.8 million years ago. [cite web | author = Perlman, David | date = 2001-07-12 | title = Fossils From Ethiopia May Be Earliest Human Ancestor | work = San Francisco Chronicle, as reported in National Geographic News | url = http://news.nationalgeographic.com/news/2001/07/0712_ethiopianbones.html]
In 1992-1993 a research team headed by Dr Timothy White discovered the first "A. ramidus" fossils—seventeen fragments including skull, mandible, teeth and arm bones—from the
Afar Depressionin the Middle Awashriver valley of Ethiopia. More fragments were recovered in 1994, amounting to 45 percent of the total skeleton. Features of the foramen magnumand leg fragments are indicative of bipedalism. [cite web | title = Ardipithecus ramidus | url = http://www.archaeologyinfo.com/ardipithecusramidus.htm | accessdate = 2008-01-18] [cite web | url = http://www.talkorigins.org/faqs/homs/species.html | title = Hominid Species | accessdate = 2008-01-18]
"A. kadabba" is dated to have lived between 5.8 million to 5.2 million years ago. The
canine teethshow primitive features, shared with " Sahelanthropus" and " Orrorin", that distinguish them from those of more recent hominins. It has been suggested that "A. kadabba" is the most recent common ancestor of "Homo" and "Pan". Anthropologists Yohannes Haile-Selassie, Gen Suwa, and Tim D. White published an article suggesting that the presence of a "canine cutting complex" indicates a need for relocation in hominid evolutionary history. [cite journal |last=Haile-Selassie |first=Yohannes |authorlink= |coauthors=Suwa, Gen; White, Tim D. |year=2004 |month= |title=Late Miocene Teeth from Middle Awash, Ethiopia, and Early Hominid Dental Evolution |journal=Science |volume=303 |issue=5663 |pages=1503–1505 |doi=10.1126/science.1092978 |url= |quote=|pmid=15001775 ] Since "A. ramidus" is lacking the canine cutting complex, the authors argue, it is reasonable to infer the canine cutting complex, which is present in modern day chimpanzees, is a primitive trait which was lost during hominin evolution. The specific name comes from the Afarword for "basal family ancestor".cite book| last = Ellis| first = Richard| authorlink = Richard Ellis (biologist) | title = No Turning Back: The Life and Death of Animal Species| publisher = Harper Perennial | date = 2004| location = New York| pages = 92| isbn =0-06-055804-0 ]
On the basis of bone sizes, "Ardipithecus" species are believed to have been about the size of a modern chimpanzee.
The toe structure of "A. ramidus" suggests that the creature walked upright, and this poses problems for current theories of the origins of hominid
bipedalism: "Ardipithecus" is believed to have lived in shady forests rather than on the savannah, where the more energy efficient locomotion permitted by bipedalism would have been an advantage.
* [http://news.bbc.co.uk/2/hi/science/nature/4187991.stm BBC News: Amazing hominid haul in Ethiopia]
* [http://www.nytimes.com/2006/05/18/science/18evolve.html?pagewanted=2&_r=1 NY Times: Two Splits Between Human and Chimp Lines Suggested]
* [http://www.mnsu.edu/emuseum/biology/humanevolution/ramidus.htm Minnesota State University]
* [http://www.archaeologyinfo.com/ardipithecusramidus.htm Archaeology info]
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