Question

Of the three earliest hominins, only one species is considered to be a definite biped. Answer the following questions. In your response please explain the significance/function of any anatomical traits you refer to.

a. Which of the early (before Australopithecus) species is definitely (as opposed to possibly) a biped? How do we know?

b. Why are the other species only possibly bipeds?

Answer 1

The earliest hominis are - Sahelanthropus , Orronin and Ardipethecus. Among all of them it is believed that definate bipeds are the sahelanthropus tchdensis found in 2002.

The first hominine actually discovered were Ardipithecus and it is found out that they could be capable of bipedalism based on the presence of single toe bone but then it has been considered that for bipedalism walk must need more postcranial , but the best preserved skeleton is of this species and that has most of the part of skull and teeth, crushed or broken pelvis, hands ans forearms ,leg and foot but no humerus ,scapula and very less of ribs and vertebrae so it can not be an optimam structure to use for bipedal walk and so this species can not be considered for sure about the definite bipedal activity presence as there are no knuckle walking features.

Now, for Orronin it is believed that they can also be bipedals because obturator groove was observed in femur so it is most possible that orronin can be bipeds but also they are believed to be the climber based upon the other parts they found so it goes in confusion with the bipedal walking or climbing locomotive capacity combination.

For Sahelanthropus, they got a very little of parts of skulls and other parts but virtually they have used software and mathematically calculated he possibiity of bipedalism. They have found out that the most definite bipedal locomotion is sure for these species as

So, it is proven that compared to Sahelanthropus hominis are closest and oldest hominine which had the capacity of bipedal motion to change locations and other two are possibly not the one.