Final answer:
Australopithecus split into two genera: the gracile australopiths (including species such as A. anamensis, A. afarensis, A. africanus, and A. garhi) and the robust australopiths (under the genus Paranthropus, including P. robustus, P. boisei, and P. aethiopicus).
Step-by-step explanation:
The genus Australopithecus, commonly known as australopiths, evolved in eastern Africa around four million years ago and eventually split into two distinct evolutionary paths. The australopiths are typically divided into two broad categories based on their physical characteristics: the gracile australopiths and the robust australopiths. Species considered to be the gracile australopiths include Australopithecus anamensis, A. afarensis, A. africanus, and A. garhi. On the other hand, the robust australopiths, which are classified under the genus Paranthropus, include Paranthropus robustus, P. boisei, and P. aethiopicus. These robust australopiths had a more muscular build and larger teeth adapted for a coarse vegetarian diet, distinguishing them from their gracile relatives.