The world’s oldest-known fossil primate skeleton — dating back around 55 million years — has been discovered in China, scientists have announced.
Estimated to have weighed 20 to 30 grammes, the skeleton of the tiny long-tailed creature was unearthed in an ancient lake bed in central China's Hubei province, near the course of the modern Yangtze River.
Archicebus achilles is thought to have been active during the day, to have climbed trees and eaten insects. The fossil provides key evidence of the earliest phases of human and primate evolution, an international team of scientists writing in the journal Nature said.
The skeleton dates from close to the evolutionary split leading to modern monkeys, apes, and humans — known as anthropoids and the branch leading to tarsiers or small, nocturnal tree-dwelling primates.
The findings represent a decade of intensive research by scientists using expertise at museums throughout the world.
Lead researcher Xijun Ni, a scientist at the Institute of vertebrate paleontology and paleoanthropology at the Chinese Academy of Sciences in Beijing, said: “Archicebus marks the first time that we have a reasonably complete picture of a primate close to the divergence between tarsiers and anthropoids.
“It represents a big step forward in our efforts to chart the course of the earliest phases of primate and human evolution.”
The fossil was found in sedimentary rock strata deposited in an ancient lake around 55 million years ago at a time of global greenhouse conditions, when much of the world was shrouded in tropical rainforests and palm trees grew as far north as Alaska.
John Flynn, dean of the Richard Gilder graduate school at the American Museum of Natural History, said: "To reveal the remarkable secrets that have been hidden in the rock for millions of years, we undertook extensive work, applied state-of-the-art technology, and set up intensive international co-operation behind the scenes at several museums. It took us 10 years."
The skeleton of Archicebus is around seven million years older than the oldest fossil primate skeletons known previously.
Christopher Beard, a paleontologist at the Carnegie Museum of Natural History, said: "Archicebus differs radically from any other primate, living or fossil, known to science,"
“It looks like an odd hybrid with the feet of a small monkey, the arms, legs and teeth of a very primitive primate, and a primitive skull bearing surprisingly small eyes. It will force us to rewrite how the anthropoid lineage evolved.”
PA