Maybe The Missing Link Isn't So Missing
John Noble Wilford writes in The New York Times that scientists have discovered fossils of a creature that seems to be the missing link in the evolution of some fishes from water to land animals. (Lena, who sent me the link, reminded me to tell people to look at the amazing graphic):
In two reports today in the journal Nature, a team of scientists led by Neil H. Shubin of the University of Chicago say they have uncovered several well-preserved skeletons of the fossil fish in sediments of former streambeds in the Canadian Arctic, 600 miles from the North Pole.The skeletons have the fins, scales and other attributes of a giant fish, four to nine feet long. But on closer examination, the scientists found telling anatomical traits of a transitional creature, a fish that is still a fish but has changes that anticipate the emergence of land animals — and is thus a predecessor of amphibians, reptiles and dinosaurs, mammals and eventually humans.
In the fishes' forward fins, the scientists found evidence of limbs in the making. There are the beginnings of digits, proto-wrists, elbows and shoulders. The fish also had a flat skull resembling a crocodile's, a neck, ribs and other parts that were similar to four-legged land animals known as tetrapods.
Other scientists said that in addition to confirming elements of a major transition in evolution, the fossils were a powerful rebuttal to religious creationists, who have long argued that the absence of such transitional creatures are a serious weakness in Darwin's theory.
The discovery team called the fossils the most compelling examples yet of an animal that was at the cusp of the fish-tetrapod transition. The fish has been named Tiktaalik roseae, at the suggestion of elders of Canada's Nunavut Territory. Tiktaalik (pronounced tic-TAH-lick) means "large shallow water fish."
"The origin of limbs," Dr. Shubin's team wrote, "probably involved the elaboration and proliferation of features already present in the fins of fish such as Tiktaalik."
In an interview, Dr. Shubin, an evolutionary biologist, let himself go. "It's a really amazing, remarkable intermediate fossil," he said. "It's like, holy cow."
Two other paleontologists, commenting on the find in a separate article in the journal, said that a few other transitional fish had been previously discovered from approximately the same Late Devonian time period, 385 million to 359 million years ago. But Tiktaalik is so clearly an intermediate "link between fishes and land vertebrates," they said, that it "might in time become as much an evolutionary icon as the proto-bird Archaeopteryx," which bridged the gap between reptiles (probably dinosaurs) and today's birds.
It's intriguing to speculate why these fish developed limbs in the first place. One clue is evident in the article when it states that it was a "shallow water fish." Perhaps these fish fed upon smaller fish or insects present in very shallow waters, and routinely had to struggle in the mud (closer and closer to shore) in order to find food. Over time, those fish with stronger fins (later fore-limbs) held an advantage in this regard, reproduced more readily, and so advanced the process of evolving limbs.
Norm Nason at April 7, 2006 11:36 AM
But how did they become mouth breathers?
Mad Hungarian at April 7, 2006 2:36 PM
I like your theory, Norm!
And I LOVE Tiktaalik's little knuckles!
Lena at April 7, 2006 2:51 PM
But how did they become mouth breathers?
Too much junk food and wasting time on the Internet.
LYT at April 7, 2006 7:55 PM
'In an interview, Dr. Shubin, an evolutionary biologist, let himself go. "It's a really amazing, remarkable intermediate fossil," he said. "It's like, holy cow."'
Am I the only one who thinks it's hilarious that an evolutionary biologist would use the term "holy" for anything like this? Perhaps he's a closet "fundanutter"? Possibly Hindu?
mbm at April 8, 2006 12:35 AM
Norm: The same way the lungfish did. It was expedient for survival in its environment.
LYT: For god's sake man, it's just an expression. Bye the way, I'm athiest. One last point, evolution is not an athiestic thing. It's science. Plenty of religious people -- in fact, all but the self-blinded -- believe in it.
Oligonicella at April 8, 2006 7:30 AM
Oli:
Thanks, but I think your comments were directed at the Mad Hungarian and me.
.....and it was a JOKE. See, I was thinking about....well, never mind. Little of what I do could be termed "thinking", in even the loosest sense. I will freely admit, it's not much of a joke, but then, my sense of humor is still evolving....
mbm at April 8, 2006 10:25 AM
"The same way the lungfish did. It was expedient for survival in its environment. "
Can you suggest any goood articles on this???
Mad Hungarian at April 8, 2006 12:39 PM
My chickens' feet look like tiny Tyrannasaurus Rex feet, and when they run across the pasture it's like watching that wonderful scene in Jurassic Park of the dinasours running. I love it. Personally I believe in God as the great designer who utilized evolution in the overall set up.
In the beginning God created the heaven and the earth. And God said, "Holy cow!"
chicknlady at April 9, 2006 11:00 PM
In the beginning, there was nothing. And God said, "Let their be light, and there was light." And there was still nothing, but you could see it better!
Patrick at April 10, 2006 6:11 AM
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