An Elgin anthropologist is part of a team of international researchers that discovered the fossil of a 55 million-year-old tiny primate from China that's unique because of its completeness and anatomy.
The discovery was published in today's issue of the science journal Nature.
"It's pretty exciting," said Northern Illinois University professor Dan Gebo. "A fossil like this comes around once in every 50 years, maybe 100 years."
The fossil from the Eocene Epoch was named Archicebus achilles, roughly translated as "first long-tailed monkey."
The fossil is missing only the skeleton's hands and rib cage, Gebo said.
"Usually when we get skeletons from this time period, we get a jaw, some isolated teeth -- we usually don't get a whole body," he said.
Also, its foot anatomy -- Gebo's area of expertise -- is similar to a monkey's, which sets it apart from other fossils previously discovered, he said.
"It presents us with a new combination of anatomy we've never seen in the field before," he said.
The research team was led by Xijun Ni, of the Institute of Vertebrate Paleontology and Paleoanthropology at the Chinese Academy of Sciences in Beijing.
"Archicebus marks the first time that we have a reasonably complete picture of a primate close to the divergence between tarsiers and anthropoids," Ni said in a news release. "It represents a big step forward in our efforts to chart the course of the earliest phases of primate and human evolution."
Archicebus weighed less than an ounce -- it easily would fit in the palm of a human hand -- and lived high up in the trees, chasing insects and perhaps eating a bit of fruit, Gebo said.
It probably lived about five years, trying to escape from predator birds and possibly snakes, he said.
The only living primate of this size is the Pygmy Mouse Lemur from Madagascar.
The rock-encased fossil was found about a decade ago by a farmer in a quarry near Jingzhou City, in China's Hubei province, Gebo said.
The farmer split the rock open and found the skeleton and impressions on both sides.
The farmer gave the rock to Ni, with whom Gebo previously worked in the 1990s.
The fossil is too tiny and delicate to be taken out of the rock, so at first the researchers tried to get images via a micro CT scanner. The results were mediocre, Gebo said.
Then -- after a 1½-year debate -- the fossil was sent to the European Synchrotron Radiation Facility in Grenoble, France, where NASA also gets some of its testing done, he said.
"They took X-ray slices and put them all together with computer graphics to make a three-dimensional image," he said.
Gebo's wife, Marian Dagosto, a professor of cell and molecular biology at Northwestern University in Chicago, is also among the article's authors.
She helped with the data matrix and evolutionary sequence portion of the study by analyzing the fossil's computer images, Gebo said.
Other authors include K. Christopher Beard of the Carnegie Museum of Natural History in Pittsburgh, Paul Tafforeau of the European Synchrotron Radiation Facility, and Jin Meng and John Flynn of the American Museum of Natural History in New York.
Gebo said this was his third time being published in Nature, which he called "one of the top science journals in the world."