Scientists have reconstructed the skull of an extinct ape species that lived in Spain about 12 million years ago.
The species, Pierolapithecus catalaunicus, may be crucial to understanding the evolution of great apes and humans.
A rare and remarkable fossil
Pierolapithecus catalaunicus was one of a diverse group of now-extinct ape species that lived in Europe around 15 to 7 million years ago.
The species is key to understanding the mosaic nature of hominid (great ape and human) evolution because it is known from a cranium and partial skeleton of the same individual-a rarity in the fossil record.
"Features of the skull and teeth are extremely important in resolving the evolutionary relationships of fossil species, and when we find this material in association with bones of the rest of the skeleton, it gives us the opportunity to not only accurately place the species on the hominid family tree, but also to learn more about the biology of the animal in terms of, for example, how it was moving around its environment," said lead author Kelsey Pugh, a research associate at the American Museum of Natural History and a lecturer at Brooklyn College.
The fossil was first described in 2004 by a team led by Salvador Moyà-Solà, director of the Catalan Institute of Paleontology Miquel Crusafont.
However, the cranium was damaged and distorted, making it difficult to study its anatomy and compare it to other primates.
A virtual reconstruction
To overcome this challenge, Pugh and her colleagues used CT scans to virtually reconstruct the cranium of Pierolapithecus, filling in missing parts and correcting deformations.
They then compared it to other primate species, both living and extinct, and modeled the evolution of key features of ape facial structure.
They found that Pierolapithecus shares similarities in overall face shape and size with both fossilized and living great apes, but it also has distinct facial features not found in other Middle Miocene apes.
For example, Pierolapithecus has a relatively flat face with a prominent nose, unlike most other Miocene apes that have long snouts.
It also has large canine teeth and small incisors, unlike living great apes that have small canines and large incisors.
The results are consistent with the idea that this species represents one of the earliest members of the great ape and human family.
Co-author Ashley Hammond, associate curator and chair of the Museum's Division of Anthropology indicated that Pierolapithecus is a transitional form that bridges the gap between more primitive Miocene apes and the modern radiation of hominoids.
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A glimpse into the past
The virtual reconstruction also reveals new insights into the lifestyle and ecology of Pierolapithecus. The researchers suggested that the ape lived in a forested environment and was adapted to climbing trees.
However, unlike living great apes that use their arms to swing from branch to branch, Pierolapithecus may have used its legs to move among the trees.
Pugh stated that Pierolapithecus shows that an upright body plan preceded adaptations that allowed hominids to hang from tree branches and move among them.
This has implications for understanding how our ancestors evolved from arboreal to terrestrial locomotion.
The study, published in the journal Proceedings of the National Academy of Sciences, is part of a larger project that aims to reconstruct the evolutionary history of hominids using fossils from Europe, Africa, and Asia.
The researchers hope that their work will shed more light on how our lineage diverged from other apes and what factors influenced its diversification.
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