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Is Ida our missing link?

Filed under: Great Finds-specimens — Gary May 21, 2009 @ 9:21 pm

http://www.revealingthelink.com/more-about-ida/the-film

Atlantic Productions

The Link is a feature-length documentary film made by the award-winning Atlantic Productions with exclusive access to Ida and the team of scientists who have examined her. The film shows how microtomography, CT scans and X-ray techniques were used to examine and recreate a 3D image of the creature, revealing that this early primate was a previously unknown species and one of our earliest ancestors.

Filmed in High Definition in locations in Europe, America and Africa, this documentary special combines one of the most extraordinary finds ever made, the latest scientific techniques and state of the art graphics to take us on an epic evolutionary journey.

May
19, 2009—
Meet “Ida,” the small “missing link” found in Germany that’s
created a big media splash and will likely continue to make waves among those
who study human origins.

In a new book, documentary, and promotional Web site, paleontologist Jorn Hurum, who led the
team that analyzed the 47-million-year-old fossil seen above, suggests Ida is a
critical missing-link species in primate evolution (interactive guide to human evolution from National
Geographic
magazine).
(Among the team members was University of Michigan paleontologist Philip
Gingerich, a member of the Committee for Research and Exploration of the National
Geographic Society, which owns National Geographic News.)

The fossil, he says, bridges the evolutionary split between higher primates
such as monkeys, apes, and humans and their more distant relatives such as
lemurs.

“This is the first link to all humans,” Hurum, of the Natural History Museum
in Oslo, Norway, said in a statement. Ida represents “the closest thing we can
get to a direct ancestor.”

Ida, properly known as Darwinius masillae, has a unique anatomy. The
lemur-like skeleton features primate-like characteristics, including grasping
hands, opposable thumbs, clawless digits with nails, and relatively short limbs.

“This specimen looks like a really early fossil monkey that belongs to the
group that includes us,” said Brian Richmond, a biological anthropologist at
George Washington University in Washington, D.C., who was not involved in the study, published this week in the journal PLoS
ONE
.

But there’s a big gap in the fossil record from this time period, Richmond
noted. Researchers are unsure when and where the primate group that includes
monkeys, apes, and humans split from the other group of primates that includes
lemurs.

“[Ida] is one of the important branching points on the evolutionary tree,”
Richmond said, “but it’s not the only branching point.”

At least one aspect of Ida is unquestionably unique: her incredible
preservation, unheard of in specimens from the Eocene era, when early primates
underwent a period of rapid evolution. (Explore a prehistoric time line.)

“From this time period there are very few fossils, and they tend to be an
isolated tooth here or maybe a tailbone there,” Richmond explained. “So you
can’t say a whole lot of what that [type of fossil] represents in terms of
evolutionary history or biology.”

In Ida’s case, scientists were able to examine fossil evidence of fur and
soft tissue and even picked through the remains of her last meal: fruits, seeds,
and leaves.

What’s more, the newly described “missing link” was found in Germany’s Messel
Pit. Ida’s European origins are intriguing, Richmond said, because they could
suggest—contrary to common assumptions—that the continent was an important area
for primate evolution.

Interesting article debunking the hype

IDA tree

IDA tree

Unbridled hoopla attended the unveiling of a 47-million-year-old fossil primate skeleton
at the American Museum of Natural History in New York on 19 May. Found
by private collectors in 1983 in Messel, Germany, the press immediately
hailed the specimen as a “missing link” and even the “eighth wonder of
the world.”

Google’s
homepage evolved, incorporating an image of the new fossil – nicknamed
Ida – into the company’s logo. Now that the first description of the
fossil has been published, the task of sifting through the massive
public relations campaign to understand the true significance of the
new fossil can begin.

Ida forms the basis for a new genus and species of adapiform primate, Darwinius massillae. The adapids are a branch of the primate tree that leads to modern lemurs (see figure).

Ida’s
skeletal remains are remarkably complete, putting her in a small, elite
group of well-documented fossil primates from the Eocene (55 to 34
million years ago) that also includes her North American cousin, Notharctus.

Uniquely
for primate fossils this old, Ida’s stomach contents and a few aspects
of her soft anatomy are preserved. Like all adapiforms, Ida lacked a “toothcomb” at the front of her lower jaw – a structure that living lemurs use for grooming fur. Ida also lacked a “grooming claw
on her second toe, another difference from living lemurs. Otherwise,
Ida’s overall proportions and anatomy resemble that of a lemur, and the
same is true for other adapiform primates.

What
does Ida’s anatomy tell us about her place on the family tree of humans
and other primates? The fact that she retains primitive features that
commonly occurred among all early primates, such as simple incisors
rather than a full-fledged toothcomb, indicates that Ida belongs
somewhere closer to the base of the tree than living lemurs do.

But
this does not necessarily make Ida a close relative of anthropoids –
the group of primates that includes monkeys, apes – and humans. In
order to establish that connection, Ida would have to have
anthropoid-like features that evolved after anthropoids split away from
lemurs and other early primates. Here, alas, Ida fails miserably.

So,
Ida is not a “missing link” – at least not between anthropoids and more
primitive primates. Further study may reveal her to be a missing link
between other species of Eocene adapiforms, but this hardly solidifies
her status as the “eighth wonder of the world”.

Instead,
Ida is a remarkably complete specimen that promises to teach us a great
deal about the biology of some of the earliest and least human-like of
all known primates, the Eocene adapiforms. For this, we can all
celebrate her discovery as a real advance for science.

Chris Beard is curator of vertebrate paleontology at the Carnegie Museum of Natural History

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