May 19, 2009

Remarkably Preserved Fossil May Be Missing Link

The remarkably preserved fossil remains of a lemur-like, 47-million-year-old creature was unveiled amid great fanfare at the American Museum of Natural History in New York on Tuesday.  Some say the fossil, named Ida, is the "missing link" between modern primates "“ humans, monkeys and apes - and their more distant relatives.

Ida's preservation is so good that the outline of its fur and even traces of its last meal are visible.

However, some independent experts are critical of the hype surrounding the fossil's unveiling, and are skeptical that the fossil represents the missing link.

Ida was discovered in the 1980s in a fossil treasure-trove near Darmstadt, Germany, known as Messel Pit.  The fossil has been in a private collection since that time.

Although details about Ida have been published in only one scientific journal, PLoS One, a book and a TV documentary about the discovery are already in the works.

Jorn Hurum of the Natural History Museum in Oslo, Norway, led the investigation of the fossil's significance.  In an interview with BBC News, he described the female animal as "the closest thing we can get to a direct ancestor", and called the discovery "a dream come true".

Ida lived during a time in Earth's history known as the Eocene, which was critical for the development of early primates. Although a cursory glance at Ida shows her resembling a lemur, the creature lacks primitive features such as a "toothcomb", a specialized feature in which the canine teeth and lower incisors project forward and are elongated and crowded together.  She is also without a special claw used for hygiene.

Because of this, the team concluded that she was not merely another lemur, but a new species altogether. They have since named her Darwinius masillae, after her place of origin and the bicentenary of the birth of Charles Darwin.

Team member Dr. Jens Franzen, an expert on the Messel Pit, said Ida was "like the Eighth Wonder of the World", because of the remarkable completeness of her skeleton.

The find provided information "paleontologists can normally only dream of", he told BBC News.

Furthermore, Ida exhibits "a close resemblance to ourselves" he added, with an opposable thumb, nails instead of claws and a grasping hand.  However, some aspects of the teeth suggest Ida is not a direct ancestor, but rather more of an "aunt" than a "grandmother", he said.

"She belongs to the group from which higher primates and human beings developed but my impression is she is not on the direct line."

Independent experts waiting to see the new fossil are wary of claims that Ida might be the "missing link". Dr. Henry Gee, a senior editor at the scientific journal Nature, called the term "missing link" misleading, and said scientists would need to evaluate its importance.

"It's extremely nice to have a new find and it will be well-studied," he told BBC News.

However, it is unlikely that Ida will be in the same league as major finds such as "Flores man" or feathered dinosaurs, he said.

Dr. Chris Beard, author of The Hunt for the Dawn Monkey and curator of the Carnegie Museum of Natural History, said he was "awestruck" by the publicity surrounding Ida. Such buildup could damage the popularization of science if Ida doesn't live up to its hype, he said.

Dr. Beard has not yet seen the scientific details of the find, but said it would be very helpful to have a beautiful new fossil from the Eocene.  He called Ida "a welcome new addition" to the world of early primates.

However, "I would be absolutely dumbfounded if it turns out to be a potential ancestor to humans," he added.

In their PLoS report, the scientists do not actually claim the specimen represents a direct human ancestor, but Dr. Hurum believes that is precisely what Ida is.

The critical component to proving this lies in the details of Ida's foot, Hurum told BBC News.  The shape of the talus, a bone in the foot, looks "almost anthropoid," he said.

The team is now planning a 3D reconstruction of the foot that would prove this theory, he said.

"We're not finished with this specimen yet," Dr. Hurum said.

"There will be plenty more papers coming out."


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