Question

. What two main fossil features suggest the evolution of upright bipedalism in hominins?

Answer 1

Many quadrupedal species stand bipedally on their hindlimbs to fight. This posture may provide a performance advantage by allowing the forelimbs to strike intrinsic to high speed running, jumping and turning, the range of motion over which peak force and power can be produced.

By four million years ago, human were habitually bipedal (walking on two legs) yet had brains roughly a third of the size of a modern human's. Large increases in brain size occured even later. Upright posture and two legged walking - bipedality was the crusial and first major adaptation associated with the divergence of the human lineage from a common ancestor with the african apes.

Bipedalism was one of the first hallmarks of the hominin lineage.

Main two fossil features :

* Raymond dart identified the first australopith fossil known as Taung child from south africa. This specimen belong to the species Au. africanus and had a relatively small brain similar to the size of a modern chimpanzees. The inferior placement of the foramen magnum, dart argued suggested that the Taung child was bipedal.

* Donald johanson found the nearly complete fossilized skeleton of Lucy a member of species Au.afarensis dating to 3.2 Ma. Lucy was unique at that time because she was one of the first fossil to exhibit small relative brain size and highly derived features characteristics of bipedalism.

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