A 47-million-year-old primate fossil that is so complete that scientists can even tell what its last meal was promises to shed new light on the earliest stages of evolution of the lineage that eventually led to humans, researchers said Tuesday.
The unprecedented fossil of a lemurlike creature that probably weighed no more than 2 pounds when it was fully grown is remarkable because it is the most complete primate specimen ever obtained.
For the most part, the story of primate evolution has been pieced together from fossilized skulls, jawbones and the occasional foot — leaving large gaps in anatomy for researchers to fill in with informed speculation.
“This fossil is so complete . . . it is unheard of in the primate record,” said paleontologist Jorn H. Hurum of the University of Oslo in Norway. “You have to get to a human burial to see something this complete.”
Hurum is the lead author of a paper in the online journal PLoS One as part of a massive publicity campaign. The information about the primate was revealed at a news conference presented like a Hollywood premiere at the American Museum of Natural History in New York, where a replica of the fossil is on display. Even Mayor Michael Bloomberg showed up for the event.
A book about the discovery, called “The Link,” will be published today by Little Brown and Co., and a documentary of the same name will be shown on the History Channel on Monday.
Asked about the unusual amount of hype surrounding the announcement, Hurum was unrepentant. “That’s part of getting science out to the public, to get attention,” he said. “I don’t think that is so wrong.”
The fossil is being promoted as a kind of “missing link” in the evolution of humans. But the researchers are more circumspect.
“It is a representative of an ancestral group giving rise of all kinds of higher primates,” Hurum said. “We are not dealing with our great-great-great- grandmother, but perhaps our great-great-great-aunt.”
The fossil is “the most completely preserved fossil primate that has ever been found,” said paleontologist Tim White of the University of California, Berkeley, who was not involved in the research. “It preserves things that are almost never preserved — stomach contents, tissues, hair. That only happens in very unique circumstances.”
In this case, the unique circumstance is the Messel Shale Pit, a world-renowned fossil source in Germany about 25 miles southeast of Frankfurt. Formed by a volcanic eruption nearly 48 million years ago, the shale in the pit has yielded a bounty of fossils from the Eocene epoch, when that region of Germany was a tropical forest.
Animals that fell into the volcanic lake sank to the bottom and lay virtually undisturbed. The cocktail of minerals in the water and sediment contributed to preservation.
The fossil, formally called Darwinius masillae but nicknamed Ida after Hurum’s daughter, was found by amateur fossil hunters in 1983. Ida was broken in half, and the lower portion was sold to the Wyoming Dinosaur Center in Thermopolis. The top remained in a private collection out of the reach of scientists until two years ago, when it was offered to the Natural History Museum at the University of Oslo for $1 million. After negotiations, it was purchased for “substantially less,” Hurum said.
At this point, researchers quickly realized that the two parts present virtually the entire animal. All that is missing is part of the left leg, broken off from the knee down, probably when the fossil was collected.
Ida is about 23 inches long from the tip of her nose to the tip of her tail, “like a small cat in size,” Hurum said. She was an adolescent, about 9 months old, researchers say.
Ida has opposable thumbs, which places her squarely in the primate family. She has fingernails — not claws as would be expected from a more primitive animal. The talus or ankle bone in her foot is identical to that in humans, but smaller.
The middle teeth in her mouth are paler than the rest of the teeth. “Those are baby teeth,” said anthropologist B. Holly Smith of the University of Michigan.
Her left wrist had been broken and was healing, which may have limited her mobility. At the time of her death, she probably was drinking from the lake and overcome by fumes, the fate of many animals found in the Messel pit.
Her last meal, by the way, was berries and a salad.
