Final answer:
Paranthropus robustus and Paranthropus boisei are robust australopithecines from about 1.5 to 2 million years ago and 2.3 to 1.2 million years ago respectively. Paranthropus aethiopicus is older, and dated to about 2.5 million years ago. None are considered direct ancestors of modern humans.
Step-by-step explanation:
The species Paranthropus robustus and Paranthropus boisei are both part of a group known as robust australopithecines. Paranthropus robustus, discovered by Robert Broom in South Africa, exhibited features adapted to a diet of hard nuts and seeds, such as a sagittal crest and a flared zygomatic arch. This species has been dated to approximately 1.5 to 2 million years ago. Paranthropus boisei, discovered by Louis and Mary Leakey in the Eastern Rift Valley of Africa, and known for its distinctive morphology including a large jaw and flat face, is estimated to have lived about 2.3 to 1.2 million years ago. Both species are not considered direct ancestors of modern humans but represent a side branch in the hominin evolutionary tree. On the other hand, Paranthropus aethiopicus, dated to about 2.5 million years ago and found in Ethiopia, is considered to have characteristics intermediate between the robust and gracile australopithecines. Despite the clear distinctions in their morphology suggesting different adaptations, all three species of the Paranthropus genus went extinct more than one million years ago and are valuable to our understanding of human evolution.