Ida the "missing link"

[rayilynlee <rayilynlee@xxxxxxx>]

It's caught at a really very interesting moment [in the animal's life] when
it fortunately has all its baby teeth and is in the process of forming all
its permanent teeth," said Dr Holly Smith, an expert in primate development
at the University of Michigan in Ann Arbor, who was part of the team. "So
you have more information in it than almost any fossil you could think of."
The fossil's amazing preservation means that the scientific team has managed
to glean a huge amount of information from it, although this required new
X-ray techniques that had not previously been applied to any other
specimens.
The researchers believe it comes from the time when the primate lineage,
that diversified into monkeys, apes and ultimately humans, split from a
separate group that went on to become lemurs and other less well known
species.
Crucially though, Ida is not on the lemur line because she lacks two key
characteristics shared by lemurs - a grooming claw on her second toe and a
fused set of teeth called a tooth comb. Also, a bone in her ankle called the
talus is shaped like members of our branch of the primates. So the
researchers believe she may be on our evolutionary line dating from just
after the split with the lemurs.
According to the team's published description of the skeleton in the journal
PLoS ONE, Ida was 53cm long and a juvenile around six to nine months old.
The team can be sure Ida is a girl because she does not have a penis bone.
"She was at this vulnerable age where you are no longer right with your
mother," said Smith, "Just as you leave weaning you are not full grown, but
you are on your own."
The unprecedented preservation of Ida meant working out how she died was
more like a modern day crime scene investigation than the informed
guess-work that palaeontologists usually make do with. The team noticed that
she had a broken wrist that had begun to partially heal. The injury did not
kill her, but they speculate that it contributed to her premature demise.
"It might be that her mother dropped her once or that she fell down from a
tree earlier in her life," Smith said. She survived the accident, but her
climbing abilities would have been impaired. Unable to drink from water
trapped by tree leaves, she would have had to venture down to the lake to
drink. This would have proved to be a fateful decision.
The huge range of magnificently preserved fossils at Messel suggest that the
volcanic lake was a death trap. Scientists believe that it sporadically let
forth giant belches of poisonous volcanic gases that would have immediately
suffocated anything in, around and even over the water. Ida would then have
fallen into the water and been preserved in the sediment deep at the bottom.
. Atlantic productions' programme, Uncovering Our Earliest Ancestor: The
Link, will be broadcast in the UK on Tuesday, 26 May at 9pm on BBC1
(revealingthelink.com). Colin Tudge's book, The Link, is published on 20 May
by Little Brown.

Rayilyn Brown
Director AZNPF
Arizona Chapter National Parkinson Foundation
rbrown@xxxxxxxxx

----------------------------------------------------------------------
To sign-off Parkinsn send a message to: mailto:listserv@xxxxxxxxxxxxxxxxxxxx
In the body of the message put: signoff parkinsn