Scientists utilizing cutting-edge X-ray imaging technology have reconstructed the face of a great ape that lived over 12 million years ago. This groundbreaking research sheds light on a crucial moment in primate evolution, providing insights into the origins of humans. The study, published in the journal Proceedings of the National Academy of Sciences, presents the first accurate three-dimensional image of the great ape Pierolapithecus catalaunicus, revealing a blend of features seen in both living and extinct primate species. This unique blend of physical characteristics has puzzled scientists for some time.
Lead author Sergio Almécija, a senior research scientist at the American Museum of Natural History, explained, “The story of living apes is essentially a mystery. We have numerous fossils of apes that are very different from the living ones, but there is no agreement on their classification within the branches of living apes.” The fossilized remains used in this study were discovered two decades ago during the expansion of a landfill in northeastern Spain. The remains represent the only known example of Pierolapithecus.
During the Mid-Miocene epoch, millions of years ago, the Earth boasted ten times as many great ape species as exist today, spread across a broader geographical area that included parts of Asia and Europe. These apes inhabited woodlands that were considerably less hot and wet than the modern-day tropical forests where the endangered great apes reside. However, the Mid-Miocene environment underwent significant changes. Around 9.6 million years ago, changes in climate eradicated vast portions of the evergreen forest habitats in Eurasia, triggering an extinction event known as the Vallesian Crisis. Most apes residing in the region perished.
Pierolapithecus occupied a critical period, existing just before the Earth’s climate drastically transformed and decimated numerous ape species. The well-preserved fossils from this period are notably scarce. Carol Ward, a professor at the University of Missouri School of Medicine, commented on the limited fossil record, stating, “The fossil record can be cruel. It gives us broken fossils, distorted fossils, and fragmentary fossils.” The remains of Pierolapithecus, including the face, portions of the hands and pelvis, a foot, vertebrae, and ribs, were discovered as a landfill was established. Initially, researchers suspected that the bone fragments had been damaged or bent during their time buried underground. However, further analysis revealed that the bone fragments had naturally shifted and separated over time, creating a complex puzzle.
The scientists employed micro CT scanning technology, which offers higher resolution than traditional hospital CT scanners, to examine Pierolapithecus. Kelsey D. Pugh, the research associate at the American Museum of Natural History who led the CT analysis, emphasized the painstaking nature of the reconstruction process. Pugh had to determine which fragments were bone and which were rock, segmenting the damaged specimen and then painstakingly repositioning each piece. The size of the pointed canine teeth indicated that the reconstruction represented a male Pierolapithecus. The creature would have weighed around 75 pounds, similar to the size of a female chimpanzee.
Almécija highlighted that what surprised the researchers the most was that Pierolapithecus possessed a mosaic blend of features. The great ape’s face resembled that of present-day great apes, including orangutans, chimpanzees, and gorillas, while its hands were shorter, more akin to monkeys. Living apes possess long hands for suspending themselves on branches, using their curved digits like hooks. In contrast, Pierolapithecus exhibited a torso closer to that of living apes and humans, with an upright posture that allowed humans to walk on two feet and apes to climb and suspend from tree branches. Monkeys, on the other hand, possess a more primitive bodily form similar to cats or dogs.
Professor Kieran McNulty from the University of Minnesota praised the detailed reconstruction work, noting that it required extensive effort. Additionally, the authors of the study have made their CT scans of Pierolapithecus available to other scientists, a practice not commonly seen in paleontology and paleoanthropology. This transparent approach allows other teams to attempt their reconstructions of the species, contributing to a better understanding of the evolution of hominids, the primate family that includes humans. Ultimately, this research will help scientists answer the intriguing question of why these evolutionary changes occurred, allowing them to piece together the story of our origins.
