The remains of a 55-million-year-old monkey found in China that could fit in the palm of one’s hand and had man-like feet and face, may offer a new timeline on when humans split from their primate cousins, scientists said.
An analysis of the nearly complete 3-inch (8-centimeter) skeleton concluded it was from the tarsiiforme family of primates, which includes lemurs, and shared characteristics of anthropoids, a group of higher primates that includes humans, according to a report in the journal Nature. The creature lived 10 million years after dinosaurs went extinct, scientists said.
The discovery of the new primate, named Archicebus achilles because of its man-like heel bone, narrows the time frame when tarsiiformes and anthropoids diverged. It also backs the hypothesis that the earliest primates were small mammals active in the daytime, climbed trees, and ate mainly insects, researchers said in the June 5 paper.
“This creature is very bizarre, it has a combination of features from tarsiiformes and from anthropoids,” said study author Ni Xijun of the Beijing-based Institute of Vertebrate Paleontology and Paleoanthropology. “It also has nails on all its fingers and toes, a rounded face and brain case, very short snout, and front-facing eyes unlike with other small creatures.”
Very Long Tail
The new primate from the Eocene period, which lasted from 56 million to 34 million years ago, also has slender limbs and a disproportionately long tail when compared with its body. Absence of large eyes, which is common among nocturnal animals, mark it as a diurnal, or daytime, animal, according to the report.
The earliest anthropoid fossil found previously, also in China, is from about 45 million years ago, said Ni, citing an earlier study published in Nature in January 2000.
“We actually don’t know a lot about early anthropoids, but we now know quite a lot about tarsiiformes from this fossil, and we can deduce that the earliest anthropoid could be very similar,” said Ni, whose institute is part of the Chinese Academy of Sciences, in a telephone interview from Beijing.
The researchers had obtained the fossil in 2003 from a farmer, who found it while prospecting for relics in an abandoned paleontological site in central China’s Hubei province. The group then spent the next 10 years analyzing the petrified remains.
With an almost complete skeleton for the earliest primate found, scientists that find other fossils in future can use it as a reference, Ni said, adding this “will to help clarify a lot of theories about the origins of anthropoids.”
“From an evolutionary point of view, we know human beings belong to a large family of primates, but when did we separate from the other members?” he said. “Our finding sets up a milestone for that.”
-- Daryl Loo, Angela Zimm