Paranthropus boisei

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Paranthropus boisei
Fossil range: Pliocene-Pleistocene

OH 5

Scientific classification

Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Primates
Family:	Hominidae
Genus:	Paranthropus
Species:	P. boisei

Binomial name

†Paranthropus boisei
(Mary Leakey, 1959)

Paranthropus boisei (originally called Zinjanthropus boisei and then Australopithecus boisei until recently) was an early hominin and described as the largest of the Paranthropus species. It lived from about 2.6 until about 1.2 million years ago during the Pliocene and Pleistocene eras in Eastern Africa.

1 Discovery
2 Morphology and interpretations
3 Fossils
- 3.1 Other well preserved specimens
4 See also
5 External links

[edit] Discovery

First discovered by anthropologist Mary Leakey in July 1959 at Olduvai Gorge, Tanzania, the well-preserved cranium OH 5 (nicknamed "Nutcracker Man") was dated to 1.75 million years old and had characteristics distinctive of the gracile australopithecines. Mary and her husband Louis Leakey classified the specimen as Zinjanthropus boisei: "Zinj" for the medieval East African region of Zanj, "anthropus" meaning ape or ape-human, and "boisei" for Charles Boise (the anthropologists team’s funder at the time). Paranthropus boisei (as the species was eventually categorized) proved to be a treasure especially when the anthropologists son Richard Leakey considered it to be the first hominin species to use stone tools. Another skull was unearthed in 1969 by Richard at Koobi Fora near the Lake Turkana region.

[edit] Morphology and interpretations

The brain volume is quite small, about 500 and 550 cm³, not much larger in comparison to Australopithecus afarensis and Australopithecus africanus. It had a skull highly specialized for heavy chewing and several traits seen in modern day gorillas. P. boisei inhabited the dry savannah grasslands and woodland territories. Males weighed 68 kg (150 lb) and stood 4 feet 3 inches (1.3 m) tall, while females weighed 45 kg (100 lb) and stood 3 feet 5 inches (1.05 m) tall. The average adult males were almost twice the weight and height as the females, giving them the greatest sexual dimorphism recorded of all identified hominins. The back molar teeth were about 4 times larger than those of modern humans.

No stone tool implements have been found in direct association with P. boisei; when first discovered Richard Leakey believed they had mastered tools. However, the first fossil of Homo habilis proved to be one of the first to acquire tool technology. Previously Richard Leakey believed the species was a direct ancestor of Homo sapiens but more modern analyses have changed the theory, and place it on a separate evolutionary route unrelated to the genus Homo. Presently it is assumed that this species was not remarkable as to acquiring unique intelligence compared with more modern hominins. Instead the dentition (especially observed in the back molars and pre-molars) was built for tough chewing materials such as ground tubers, nuts and likely leaves in the grasslands. This is supported by the correspondingly widened zygomatic arches and large sagittal ridge, similar to that found in modern gorillas.

[edit] Fossils

In 1993, A. Amzaye found fossils of P. boisei at Kronso, Ethiopia. The partial skull's designation is KGA10-525 and is dated to 1.4 million years ago. It is the biggest skull specimen ever found of P. boisei. It has been claimed as the only remains of the species found in Ethiopia; all others have been in other parts of Eastern Africa. The oldest specimen of P. boisei was found in Omo, Ethiopia and dates to 2.3 million years old classified as (L. 74a-21) while the youngest speciemen from Olduvai Gorge dates 1.2 million years old classified as OH 3 and OH 38.

[edit] Other well preserved specimens

OH 5 "Nutcrackerman" is the first P. boisei found by Mary Leakey at Olduvai Gorge, Tanzania belonging to an adult male (circa. 1.75 mya).

KNM ER 406 is a small partial cranium discovered by H. Mutua and Richard Leakey in 1969 found at Koobi Fora, Kenya displays large zygomatic arches, a cranial capacity of 510 cm³ (circa. 1.7 mya).

KNM WT 17400 a partial cranium with similar characteristics as KNM WT 17000 "Black skull" belonging to Paranthropus aethiopicus. The skull was found at West Turkana, Kenya (circa. 1.7 mya).

ER 406 was found by Richard Leakey and H. Mutua in 1970 at Koobi Fora, Kenya is a partial cranium most likely identified as belonging to a female (circa. 1.7 mya).