The members of the
genus Australopithecus--Australopithecines--are supposed by researchers to be the first common ancestor of apes and men, and they are the evolutionary step before the genus
Homo.
The "
robust" in
robust Australopithecines refers not to the body, but to the jaws. Robust Australopithecines developed _gigantic_ teeth and jaws for the purposes of chomping down roots and fibers. To accomodate such gigantic jaws, they needed more muscle, so they evolved this thing called a
sagittal crest to offer more surface area on the skull for muscle. They also had a fairly pronounced
sexual dimorphismSome species that were robust Australopithecines include
Australopithecus robustus and
Australopithecus boisei. Robust Australopithecines are thought to have ultimately gone
extinct, being an evolutionary
dead end. Some researchers have suggested moving them into a new
genus to mark their
divergence from the other Australopitheceans (called
gracile Australopithecines), which had more delicate features, sharper teeth, and ultimately evolved into modern
apes and
men.