The Indian Express , 07 April 2006
Discovered: The possible missing link between sea and land animals
NEW York: Scientists have discovered fossils of a
375-million-year-old fish, a large scaly creature not seen before, that they say
is a long-sought missing link in the evolution of some fishes from water to a
life walking on four limbs on land.
In two reports today in 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.
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.” —JOHN NOBLE WILFORD