Rudolfensis was a hominid species that lived between 2.5 to 1.9 million years ago in east Africa, and was contemporary with Homo habilis. It was discovered by Bernard Ngeneo (of Richard Leakey’s team) in 1972 at Koobi Fora in Kenya, and named in 1986 by V. P. Alexeev.
Weight: estimated to be 50 kg
Height: unknown, though some scientists speculate that this species may have reached close to six feet in males
Cranial capacity: 750 cc
Habitat: Semiarid savanna
The majority of what we know about Rudolfensis comes from cranial evidence. This species was less robust than the Australopithecines and sexually dimorphic. The zygomatic arches were smaller, and there was no sagittal crest. The face was orthognathic (not prognathic) and the brow ridges had become much less prominent, which indicates a flatter and more modern facial structure. The brain case was relatively large, and more rounded. The forward placed foramen magnum, as well as what limited post-cranial fossil evidence we have, indicates a bipedal species.
Rudolfensis had large teeth, with broad molars and premolars. However, the molars, incisors and canines were beginning to tend towards uniformity in size, with no one tooth type being favored. This dentition points to a diet less reliant on vegetation, and perhaps favoring fruits and meat (obtained through hunting or scavenging).
When first discovered, the Rudolfensis fossils found were thought to be Homo habilis. It was assumed that there had been only one species in the genus Homo two million years ago, and that this species (Habilis) had evolved in a linear fashion into modern humans. But the pronounced differences in cranial features (larger braincase and more robust than Habilis) lead researchers to name Homo rudolfensis an entirely new species. Unfortunately, until more (and more complete) fossils are found, it is impossible to definitively name Homo rudolfensis’ place in human evolution.
This species may have been a tool user. The cranial capacity points to an intelligence that would have been able to manufacture Oldowan tools, but Rudolfensis fossils have never been found in conjunction with stone tools.
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