January 13, 2014 — A fish with legs? It sounds preposterous, but ancient fossils unearthed in the Canadian Arctic reveal a fish that had skeletal features similar to animals with legs, researchers said Monday.
The find challenges the widely held view of evolution that hind limbs did not begin to form until creatures left the oceans and began living on land.
And it provides a powerful insight into the pivotal episode when creatures emerged onto land: If the authors are right, we can trace our arms — and our legs — to fish fins.
“That wrist you use to write with, the neck you use to move your head around with, the lungs you’re using to breathe . . . all derive from parts in the bodies of fish. Your hands and arms derive from parts of the fins,” said Neil Shubin, a professor of anatomy at the University of Chicago who was one of the leaders of the work. “What the fossil record tells us is how deeply we are connected to life on the rest of the planet. In this case, this tells us how closely we are related to fish.”
The 375-million-year-old fish Tiktaalik roseae was first written into biology textbooks in 2006, when a team of three paleontologists discovered a fossil of the curious crocodile-like fish, showing it had front fins resembling limbs, with elbows and primitive wrists. The same team — which included a renowned Harvard paleontologist who has since died — said in Monday’s announcement that Tiktaalik also had surprisingly large pelvic bones. That suggests the transitional creature did not just have what researchers often refer to as “front-wheel drive,” but was shifting to “all-wheel drive” although it still lived in the water.
Read the full story at the Boston Globe