The fossil remains of A.
robustus and A. boisei represent the development of a hominid
whose cranium and dentition reflect a specialized diet. These two robust
austropithecines have been lumped together because they appear to have similar
adaptations. At the present time it is unclear where the connection between
these hominids and earlier forms is located specifically although there
are signs of possible variations in adaptations among A. Afarensis remains.
The discovery of a fossil known as WT17000 has helped to some degree in
clarifing possible connections. It is likely that there is an evolutionary
linkage with either A. afarensis or A. africanus. Dating of WT17000: about 2.65 million years ago. Dating of A.robustus and A. boisei fossils is much later, however, from about 2.0 million years ago to possibly as late as 800,000 years ago. Most paleoanthropologist believe that the robust australopithecines went extinct because of their inability to adapt to changing environmental conditions and direct competition from other, more successful hominds.
