May 19, 2009 — -- Scientists say a 47-million-year-old fossil found in Germany may be a key link to explaining the evolution of early primates and, perhaps, telling them about developments that led to modern human beings.
The fossil, of a young female that probably resembled a modern-day lemur, is described as "the most complete primate fossil ever found." It is small -- its body is about the size of a raccoon -- but it has characteristics found in later primates and in humans.
"We realized, when I was offered this specimen," said Dr. Jorn Hurum of the University of Oslo, who led the two-year effort to determine the fossil's importance, "that it was the most complete primate in the fossil record."
The fossil was unveiled today amid great fanfare at a news conference at the American Museum of Natural History in New York City. Hurum nicknamed it "Ida," after his own six-year-old daughter.
It has, among other things, opposable thumbs, similar to humans' and unlike those found on other modern mammals. It has fingernails instead of claws. And by examining the structure of its hind legs (one of which is partly missing), scientists say they can see evidence of evolutionary changes that would eventually lead to primates standing upright.
A detailed description of the fossil is being published today in the online journal Public Library of Science - One (PLoS One for short). The cable channel History, which bought the North American documentary rights to the find, provided exclusive material to ABC News, although many details were kept under wraps until today.
"She is a transitional species showing characteristics from both the non-human (prosimians and lemurs) and human (anthropoids, monkeys, apes and man) evolutionary lines," said the producers in a statement reviewed by the authors of the PLoS One paper.
The unveiling was part of a large publicity campaign by History, which plans to show its documentary, "The Link," on Monday night. There is a companion book from Little Brown, as well as a Web site. New York City Mayor Michael Bloomberg made an appearance at the news conference. The fossil will be shown on "Good Morning America" Wednesday.
But there was a divide between the documentary producers and the scientists over the importance of the find.
"In this time of economic hardship, it is nice to turn to another time, 47 million years ago, to the story of a little girl, who possibly connects to us," said Anthony Geffen of Atlantic Productions, which produced the documentary.
But Jens Franzen of the Senckenberg Research Institute in Germany, who was on the team assembled to examine the fossil, said, "I don't think so, that we are dealing with a direct ancestor.
"We are not dealing with our grand, grand grandmother, but perhaps with our grand, grand, grand aunt."
In response to a reporter's question, Hurum also agreed it would be hard to call "Ida" a direct human ancestor. But he said he was comfortable with the publicity surrounding it.
"That's part of getting science out to the public, to get attention," he said. "I don't think that's so wrong."
Remains from a German Caldera
The fossil was discovered by amateur fossil hunters in 1983 in a mile-wide crater called the Messel Shale Pit, not far from Frankfurt. Scientists speculate that at one time the pit was a volcanic caldera, where animals got caught and their remains unusually were well preserved. The amateurs saw that they had a very good fossil, but they did not recognize its potential importance.
The location, a UNESCO World Heritage Site, has been the source of many other fossils from the Eocene Period, about 50 million years ago.
The fossil was shown by collectors to Dr. Hurum, who brought in colleagues from Oslo and from the Senckenberg Research Institute to authenticate the find. They bought the specimen so that it would not disappear into private hands.
Examination of the fossil went on for two years. They have called the specimen Darwinius masillae. The researchers were able to keep their work secret until word leaked out last week.
Hurum's team said 95 percent of the fossil's skeleton appears intact. It has a long, curling tail. X-rays show it was young; probably about nine months in age. It had baby teeth and, beneath them, adult teeth forming to replace them. There also was evidence that the animal had once broken its wrist.
It is hard to say what the find may do to the modern understanding of evolution. The fossil, for one thing, is far older than any of the human ancestors other scientists have reported finding in what is now eastern Africa. "Lucy," probably the best-known African fossil that is generally accepted as pre-human, is somewhat more than 3 million years old.
"Ida" is also different in many ways from later animals, said Holly Smith of the University of Michigan, who was brought in to examine the fossil's teeth for clues to its development. For one thing, Smith said, the fossil had all its baby teeth, and all its adult teeth as well. Modern children lose their front baby teeth around age 6, but molars in the back of the jaw do not develop for several more years.
"This whole species grew up fast," Smith said. "You wouldn't find that in a great ape or in a human."
The fossil, encased in plastic, was shown to reporters. It will be returned to Oslo. A plaster cast will go on display at the Natural History museum in New York.
"This discovery represents both great minds and a great find," said Ellen Futter, president of the museum.