Started out as a fish. How did it end like this?

Tiktaalik first became known to humans in 2004 after skulls and other bones from at least 10 specimens appeared in ancient openings in the Nunavut Territory of the Arctic. The discoverers, a team of paleontologists including Neil Shubin of the University of Chicago, Ted Daeschler of the Academy of Natural Sciences in Philadelphia and Farish Jenkins of Harvard University, described their findings in two 2006 Nature articles.

A local council of elders known as the Inuit Qujimajatuqangit Katimajiit was consulted, and they gave Tiktaalik its name, which can be translated to a large freshwater fish living in the low tide, in the Inuktitut. The fossils have since been returned to Canada.

Scientists had been looking for a fossil like Tiktaalik, a creature on the edge of limbs, for decades. And where other fossils required some explanation, Tiktaalik’s obvious anatomy – a fish with (almost) feet – made it the perfect icon for evolution, located right between water and land.

Even then, the fossil fish hit a popular nerve and arrived on the heels of the case of a lawsuit in Pennsylvania that ruled against teaching creationism as an alternative to evolution in high school biology. For Dr. Shubin’s society’s collective desire to throw Tiktaalik back into the water is a bit of a relief: You would only want to throw the fish if you believed in evolution, “which to me is a beautiful thing,” he said.

Da Ms. Deretsky illustrated Tiktaalik, she portrayed it with its derrière immersed in water, as the back half of the fossil was a mystery at the time. But in the years since, scientists have collected more than 20 samples and seen more of its anatomy, including its pelvis, dorsal fin and skull joints.

In particular, computed tomography scans taken by Justin Lemberg, a researcher at Dr. Shubin’s laboratory, has made it possible for scientists to look into rocks to see the bones inside. The scans spawned 3D models of Tiktaalik’s invisible parts. Some scans revealed that Tiktaalik had unexpectedly massive hips (more like Thicctaalik) and a surprisingly large pelvic fin. The fish, instead of pulling itself with only its forefingers, like a wheelbarrow, seemed to use all four fins to get around, like a jeep.

Other scans revealed the delicate bones in its pectoral fin. In contrast to the symmetrical rays of the fish fins, Tiktaalik’s fin bones were noticeably asymmetrical, allowing the joints to bend in one direction. “We think it was because these animals interacted with the earth,” said Thomas Stewart, a future evolutionary and evolutionary biologist at Penn State University.

Leave a Comment

Your email address will not be published.