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Re: questions about the Odontochelys study



Tim Williams wrote:

With the disclaimer that I don't know all that much about turtles... I do know that the snapping turtle and mata mata are ambush predators, so protecting the underside may not be so important. Or at least, belly armor (plastron) is not as important as it is to aquatic turtles that spend more of their time swimming in the water column. In other words, if such aquatic ambush predators spend much of their time motionless, with their bellies close to the sediments underneath, then their bellies are not as vulnerable to attacks from below - hence the secondarily reduced plastron.

I think you're more or less right on the money. In fact, mata-matas and alligator snappers both rarely swim in the water column even while moving about; they move along largely by punting, and so they are almost always near the substrate. The reduced plastron is therefore of limited cost, while it provides substantial benefits in allowing a transiently higher "walking" gait for punting along the bottom - improved mobility for marginal cost. Common snappers free swim more often, but still spend large amounts of time bottom resting, and have the added advantage of intense offensive weaponry.


Cheers,

--Mike


Michael Habib, M.S. PhD. Candidate Center for Functional Anatomy and Evolution Johns Hopkins School of Medicine 1830 E. Monument Street Baltimore, MD 21205 (443) 280-0181 habib@jhmi.edu