Paranthropus boisei
Paranthropus boisei is an extinct human ancestor that lived in the savannah environment of East Africa from 2.3 until 1.2 million years ago. It is the most robust form of the robust australopithicenes and is specialized towards heavy chewing. The first specimen OH 5 was found by Mary Leaky at Olduvai Gorge in 1959 after 28 years of searching. It was originally named Zinjanthropus boisei or Nutcracker man, named so for it's large molars and small anterior teeth. It was later renamed Paranthropus boisei though it is often called [Australopithecus boisei]. [1]
Phylogeny
Paranthropus boisei is not actually a human ancestor but rather a cousin. It was most likely descended from [Paranthropus aethipicus] and some scientists consider it a subspecies of [Paranthropus robustus]. Many of its features are similar to [Australopithecus africanus].[2]
Characteristics
There are several characteristics that are obviously Paranthropus boisei, primarily in the craniuma and dentition, such as:
- Prognathic lower face
- [Postorbital constriction] reduced
- [Infraorbital foramen] location is variable
- [Occipital Marginal sinus] present
- [Infrolatral orbital margin] reduced
- [Mental foramen] opening is variable
- [Lingual cusps] at [margin-bucca cusps] approaching internal
- [Typanic crest] with inclined plate
- [Sagittal crest] on males
- [Maxillary trigon] variable
- Upper incisor reduced
- [Molar cusps] and [cristae] well developed
- Thin and delicate wall on cranium[3]
- Cranial capacity of 450-600cc
- Large molars
- Large incisor alveolae
- Ape-like Cranial base
- Zygomatic arch of skull is wide and thick, indicating powerful masseter muscles[4]
Postcranially, Paranthropus boisei is obviously bipedal. The thigh bone is set at a low angle to the shaft, with the shaft flattened from front to back. There's a small hip joint surfact. All of these traits lead to better ballance. The pelvis is more human than chimpanzee: it is shortened and widened. The arms and thumbs appear to be similar to [Homo habilis] and Paranthropus boisei probably had an excellent precision grip.
- ↑ Paranthropus Boisei, http://anthropology.si.edu/HumanOrigins/ha/bos.html, [March 3], [2008]
- ↑ Extinct Humans, Ian Tattersall and Jeffrey Schwartz, Westview Press, New York, 2007
- ↑ Bones, Stones, and Molecules, David Cameron and Colin Grons, Elsevier Academic Press, London, 2004
- ↑ Evolution of the Human Diet, Peter Ungar, Oxford University Press, NYC, 2007