Have scientists found a missing link to the beginning of ape and human history?

A team from George Washington University and the Institut Català de Paleontologia Miquel Crusafont, writing in Science magazine last Thursday, identified a new species of small apes that have existed for 11.6 million years, called Pliobates cataloniae.

The new species provided proof that small and large apes may have coexisted before the evolutionary split of hominids (humans) and "lesser apes,” contrary to previous beliefs that small apes evolved from larger-bodied ones.

The new fossil record of Pliobates was said to have crucial implications “for restricting the last common ancestors of the two groups” or the living hominoids, potentially changing evolutionary history.

Sergio Almécija, study author and assistant professor of anthropology at George Washington University’s Center for the Advanced Study of Human Paleobiology, echoed the possibility of small and large apes coexisting.

“Alternatively, Pliobates might indicate that great apes evolved from gibbon-size ape ancestors," he said.

Previous existing fossil record lacked small apes and ancient gibbons – thus gibbons, siamangs, and other small-bodied apes today were thought to have the large ones as their ancestors, and simply were dwarfed over the course of evolution.

The partial skeleton made up of 70 fossil remains was discovered in 2011 during a landfill construction in Barcelona. It was perceived by scientists to belong to a female adult weighing 9 to 11 pounds, consuming soft fruits, and climbing and negotiating her way through branches of forest canopy.

The researchers reminded that evolution is a complex process. “[It] is not a linear process, but it’s rather more bushy,” said paleobiologist and study author David Alba.

Pliobates’ forefathers, for instance, were believed to emerge just before the split of the greater and lesser apes, a time when a lot of species had been splitting off. Pliobates are also more closely related to apes and humans than to monkeys, added Alba.

This complexity of primate evolution may also impede the process of finding common ancestry in modern specimens. The problem, according to Alba, is that extant hominoids are very few, with the list including humans, chimpanzees, gorillas, and orangutans.

This makes the new genus important in putting the pieces together, helping researchers identify which human and ape features were inherited and which ones evolved independently in the separate groups.