'Tiktaalik': New Link in Evolution's Chain - Science, slow and steady

[Patti Kane-Vanni <pkv1@erols.com>]

Today's _Philadelphia Inquirer_ Editorial Page: 
http://www.philly.com/mld/inquirer/news/editorial/14347114.htm Great play in 
the press! - Patti Kane-Vanni
Editorial: 'Tiktaalik': New Link in Evolution's Chain
Science, slow and steady

What the heck is Tiktaalik roseae?

It's a glimpse of how life pulled itself from water to land during the 
Devonian period, hundreds of millions of years ago. It's also a tribute to 
brains and incredible, shivering patience.
In the April 6 issue of Nature, a scientific team - including a 
paleontologist from Philadelphia's own Academy of Natural Sciences - 
announced the discovery of Tiktaalik roseae. The word tiktaalik comes from 
the Inuktikut language of the Nunavut territory of Canada, where the fossils 
were discovered. It means "burbot," a big freshwater fish. That's what 
Tiktaalik evidently was: It could motor in shallow water, and maybe even 
flop around on land a little.
Scientists have long pondered a 25-million-year question mark between 
Panderichthys, a fish with early features of land dwellers (385 million 
years ago), and Acanthostega, one of the first amphibians and one of the 
earliest known four-footed land dwellers (360 million years ago). (For a 
chart, see http://news.bbc.co.uk/2/hi/science/nature/4879672.stm.) What 
happened during those 25 million years?
Here praise is due Edward Daeschler, curator of vertebrate biology at the 
Academy of Natural Sciences. He, with Neil Shubin of the University of 
Chicago and others, trekked in 1999 into arctic Canada to look for a 
creature that could bridge the gap. It took them only five years of being 
very cold and frustrated, digging around in Ellesmere Island. (Entirely 
unromantic is the stuff of science.)
Payoff of payoffs: Someone noticed a fossil snout sticking out of a cliff 
wall. Eventually, the team would find three skeletons of Tiktaalik, one of 
which is about nine feet long. A homely, 383-million-year-old dude, it 
probably looked like a crocodile: flat head, eyes on top, scales. Instead of 
limbs, it had webbed fins, suggesting that it lived in shallow water. But it 
also has features you don't see in fish: the beginnings of a neck and 
wrists. Truly, this seems like a step in the transition from water to land. 
Indeed, as Daeschler says in a New Scientist article, as a transitional 
species, Tiktaalik "really split the difference right down the middle."
Some wonder aloud why we haven't found "all the fossils" yet, as if that 
makes the fossil record less than trustworthy. Hello: It's amazing we have 
any fossils. They survive only under precise geological conditions, and we 
can get at only those near the surface or otherwise accessible. Many lords 
of the past sleep in the hearts of mountains. We'll never find them, never 
know about them.
Although much of history is destroyed or deep beyond our grasp, we can 
assemble a persuasive outline of life's exuberance. Whenever a find like 
this happens, it's a tribute to astonishing luck and even more astonishing 
hard work. The discovery of Tiktaalik is very much the latter.
Caution: Although headlines about "missing links" are certainly attractive, 
they are both slightly overstressed and slightly misleading. All life is 
related, so every new species, living and past, is a link to every other. 
Evolution isn't waiting around for us to fill in the holes; it marches on. 
"Missing" simply means we haven't found it yet.
Finds like Tiktaalik are rare, as rare as the patience and endurance to 
scour the world for them. Drawing life's family tree is slow, slow, slow, 
like the move from sea to land. Much as Tiktaalik may have done, we slip 
from one territory to another, getting our land legs under us until we can 
stand on our own feet.