A new primate fossil is providing evidence that the clade of primates humans belong to split off into two families 55 million years ago.
In 2002, an almost complete fossil of a tiny primate was discovered in a bed of shale in China. Dr. Xijun Ni from the Chinese Academy of Sciences in Beijing has been working with other paleontologists since then to determine what this creature was and how it lived. They published their results this month in the journal Nature.
Archicebus achilles, as the research team named their new specimen, was the oldest in a group known as the tarsiers—tiny arboreal primates with large eyes who prey mainly on insects. The only tarsiers alive today are living in southeast Asia. Tarsiers belong to the primate clade haplorhines; the other group in this clade is anthropoids—a group including monkeys, apes, and humans.
The Nature study revealed the intricacies of Archicebus’ skeleton using brilliant x-rays that allowed the scientists to see inside rock without having to physically break into the fossil. A. achilles weighed about one ounce and was 2.8 inches long. It had small pointy teeth—great for feeding on insects—and limbs that facilitated easy tree branch swinging.
Most interesting was the shape of Archicebus’ heel—it looked more like that of an anthropoid than a tarsier heel. This fact, combined with Archicebus’ propinquity to the split between anthropoids and tarsiers, lends evidence to the hypothesis that the earliest anthropoids—our early ancestors—were tiny, insectivorous, arboreal creatures just like Archicebus.
This study was published in the journal Nature on June 5th, 2013.
The Paleontological Research Institution, Ithaca, New York, is pleased to sponsor Paleontology content for This View of Life. Founded in 1932, PRI has outstanding programs in research, collections, and publications, and is a national leader in development of informal Earth science education resources for educators and the general public.