Paleoanthropologists have discovered the well-preserved femur, tibia, and part of the pelvis of a young adult Australopithecus, a massive animal that lived between 2.3 and 1.7 million years ago, in Swartkrans. The valuable postcranial skeletal fragments revealed that this South African Paranthropus from the “Cradle of Humankind” walked primarily on two legs and was very small in size – it probably stood just over one meter tall and weighed 27 kilograms. It also appears to have been preyed upon by a predator, possibly an ancient leopard, according to a paper published in the Journal of Human Evolution.
In South Africa, near Johannesburg, lies the so-called Cradle of Humankind, a group of sites included in the UNESCO World Heritage List, which is primarily well known for its numerous fossil remains of various hominins: Australopithecus, Paranthropus, and extinct representatives of the genus Homo.
One of the most famous monuments located in this area is the Swartkrans Cave, the exploration of which began in the middle of the last century. Over the past decades, scientists have discovered many teeth, fragments of skull bones, and even almost complete skulls and jaws of ancient hominins in this location: African Australopithecus (A. africanus), early Homo, and massive Paranthropus (P. robustus). However, postcranial skeleton bones are not found there as often as scientists would like. Moreover, for example, the postcranial skeleton of Paranthropus (including East African species) is still poorly studied due to the fact that very few similar fossils are known that could be reliably associated with these hominins.
But the work continues, and this time Travis Rayne Pickering of the University of Wisconsin-Madison, along with colleagues from Germany, the United States, and South Africa, have described the results of further studies of the Swartkrans material. Several years ago, scientists at the site extracted chunks of breccia of varying sizes from a layer formed between 2.3 and 1.7 million years ago, and then carefully sorted the rock in the lab, yielding the results.
The researchers found fossilized bones in the rock that apparently belonged to a single ancient individual, designated SWT-1/HR-2b. According to paleoanthropologists, these are likely the remains of a young adult specimen of the massive Paranthropus (P. robustus). The scientists obtained a nearly complete femur and tibia, as well as part of a left pelvic bone, with the latter two lying almost in an articulated state.
After studying these finds, the scientists made several interesting observations. First, the structure of the bones suggests that the massive Paranthropus were adapted to walking on two legs on a hard surface, although this does not exclude the possibility that they could climb trees if necessary. Second, paleoanthropologists estimated the probable height and weight of this hominin, which were approximately 103 centimeters and 27.4 kilograms, respectively - about the same as that of the known fossil dwarf people (H. floresiensis) from the island of Flores. For comparison: the supposed height of Ardipithecus ramidus and Australopithecus Lucy (A. afarensis), according to scientists, was about 118 and 110 centimeters, and their body weight was approximately 32.1 and 26 kilograms, respectively. Moreover, in the case of the massive Paranthropus from Swartkrans, it remains unclear whether these remains belonged to a male or a female.
In addition, the researchers noted damage to the studied Paranthropus bones, which indicate that it was likely prey to a medium-sized or large predator. According to scientists, it is quite possible that the small hominin suffered from an ancient leopard, whose size class of prey it fell under. It is noteworthy that in the same breccia layer where the remains of this Paranthropus were found, scientists also discovered a complete leopard skull (Panthera pardus).
Many years ago, a fragment of the skull of an ancient hominin was found in Swartkrans, apparently killed by a leopard some 1.9 to 1.8 million years ago. Scientists have recently re-examined the fossil and concluded that it probably belonged to Homo erectus, rather than the massive Paranthropus, as was long believed.