Final answer:
Australopithecus robustus was a robust australopithecine with large molars for a coarse, fibrous vegetarian diet and distinctive features like a sagittal crest and flared zygomatic arch for powerful chewing.
Step-by-step explanation:
Australopithecus robustus Characteristics
Australopithecus robustus, part of the robust australopithecines under the genus Paranthropus, was likely the longest-surviving species of australopithecine in South Africa. It had a number of distinctive features that adapted it to a specific niche in its environment. One of the most pronounced differences observed in P. robustus, when compared to the gracile australopithecines like Australopithecus afarensis, is its robust craniodental anatomy. This includes a large face with a pronounced sagittal crest and a flared zygomatic arch which provided attachment points for large temporalis muscles. These adaptations allowed for powerful chewing, suited to a diet of hard nuts and seeds. Additionally, while its front teeth (incisors and canines) were smaller, its molars were large and showed heavy wear, indicating a coarse and fibrous vegetarian diet.
P. robustus, like other robust australopithecines, is not considered to be ancestral to modern humans, but rather represents a side branch of the hominin tree that eventually went extinct. The robust physical attributes of P. robustus were well-suited for its environment, indicating that these hominins were adapted to a life with significant physical demands and a specific diet.