Fossil Femur Shows Apes, Old World Monkeys Move Differently Than Ancestor main content.

Fossil Femur Shows Apes, Old World Monkeys Move Differently Than Ancestor

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Rendering depicts four adult and one juvenile primate on the branches of a tree. Artistic reconstruction of a group of Aegyptopithecus individuals on a tree during the Oligecene.
Lucille Betti-Nash (modified by Sergio Almécija)

Humans and other primate species, both living and extinct, share many similar features: opposable thumbs, flexible shoulder and hip joints, and especially large brains compared to those of other mammals. But new research suggests that some shared anatomical traits, like hip joints, evolved differently in apes and Old World monkeys than their ancestors.

A study published this week in the journal Nature Communications analyzed the first well-preserved femur of Aegyptopithecus zeuxis, a common ancestor of both Old World monkeys and apes that lived in Egypt about 30 million years ago, and found that each group’s locomotion diverged from the ancestral primate species as they adapted to different niches in their respective habitats.

“Our study shows that Aegyptopithecus preserves an ancient hip morphology not present in living anthropoid primates,” said Sergio Almécija, first author on the study and a paleoanthropologist and evolutionary biologist in the Museum’s Division of Anthropology. “As far as the hip is concerned, it seems that apes, humans, and Old World monkeys have all parted ways long ago—which would explain why they move around so differently today.”

Fossil specimen of primate femur.
Researchers used a fossil femur of Aegyptopithecus to glean details about the hip joint, a major anatomical region for inferring locomotion.
Sergio Almécija

The well-preserved femur, discovered in 2009, has provided researchers new insights into the hip joint, a major anatomical region for inferring locomotion. By using a combination of 3D morphometric analysis and evolutionary modeling, they found that living great apes—including orangutans, chimpanzees, and gorillas—may have independently developed similar hip joint anatomy that allows the flexible movement needed for navigating arboreal habitats.

“What I find really exciting about the modeling approach,” said Ashley Hammond, assistant curator in the Division of Anthropology and an author on the study, “is that we can develop better hypotheses about what drove the divergence of apes and monkeys, and the emerging picture is that navigating the environment is one of the key factors.”