By Casey Frye, CCNN Writer
According to a new paper published in Proceedings of the National Academy of Sciences, researchers have found fossils of a 375-million-year-old organism that looks part fish, part legged-animal.
The creature is named Tiktaalik roseae, and it had several features that seem like a cross between a fish and a land animal. For example, it had scales, gills, and fins, which make it similar to underwater creatures. Meanwhile, Tiktaalik also had a neck, primitive lungs, and a ribcage. Altogether, the creature may have looked something like a present day crocodile, but these aren’t the features which interest the scientists most.
The presence of shoulders, elbows, and wrists challenge the idea that animal species only acquired these features after they evolved on land. “Previous theories, based on the best available data, propose that a shift occurred from ‘front-wheel drive’ locomotion in fish to more of a ‘four-wheel drive’ in tetrapods (four-footed animals),” said co-author Neil Shubin, who is a professor of Anatomy at the University of Chicago. “But it looks like this shift actually began to happen in fish, not in limbed animals.”
Now, researchers believe that Tiktaalik may have used its limbs to slither, and later animals waddled to land where they eventually evolved into land animals.
Images courtesy of the University of Chicago.