Researchers have uncovered what is now the oldest known primate fossil, pushing our understanding of human evolution seven million years farther into history than we could see before. Discovery of the 55-million-year-old fossil allowed an international team of researchers to identify a previously unknown species, as well as an unknown genus of animals that surrounds it. The fossil sits at a juncture in evolution that helps to explain how humans, apes, and monkeys all diverged from a small primate known as a tarsier.

Archicebus achilles' skeleton was found in China near the Yangtze River. Researchers removed it from a lakebed by splitting the surrounding dirt into two parts, one containing the fossils and another containing their imprints. Since then, researchers have scanned the fossils with X-rays and created a 3D reconstruction. Dr. Xijun Ni, who led the team, said that the find "represents a big step forward in our efforts to chart the course of the earliest phases of primate and human evolution." Already, it's helped to show how distinct tarsier-like animals were from humans at an early point in their evolution.