Turtle genome comes out of its shell

12 May 2013
Posted by Kat Arney.

New data from the turtle genome has helped to shed light on the evolutionary mystery surrounding these unusual creatures, thanks to a paper published in the journal Nature Genetics by the Joint International Turtle Genome Consortium, led by researchers in Japan, China and the UK.

Turtles have a unique body plan, and a highly intriguing shell structure, and the new evidence suggests that they're actually related to birds and crocodiles, not to mention extinct dinosaurs, rather than being primitive reptiles as was previously thought. The scientists studied the green sea turtle and Chinese soft-shell turtle, and think that turtles must have split off from their dinosaur-like relatives around 250 million years ago, during the worst ever mass extinction - a catastrophe known as the Permian-Triassic extinction.

The research also helps to explain how the turtle's shell evolved, by hijacking genetic information normally used to encode limbs, providing more clues as to how subtle genetic changes can drive dramatic changes in what an organism looks like. And as an added bonus, the scientists discovered that turtles have an unusually large number of olfactory receptors, allowing them to sniff out a huge variety of different things. The soft shell turtle has more than a thousand - among the most ever found in a non-mammalian vertebrate - although quite what it's doing with them all isn't known.

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