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Re: questions about the Odontochelys study




Augusto Haro wrote:


All right, but it was just an example that turtles with a heavy
cuirass are relatively fast, and that I doubt that turtles with less
completely covering shells, as the snapping, can really be faster.
Just to say I do not know exactly to what is decreased coverage of the
bony shell in turtles related.


Is there a particular reason that you doubt a chelydrid could be faster? In any case, the shell reduction, especially in the plastron, might have more impact on aquatic locomotion than terrestrial walking. For mata-matas, as least, the plastron reduction allows the animals to take a somewhat more erect stance when punting along the bottom, and appears to greatly increase effective stride and speed (they're actually quite rapid movers when need be). This is all unpublished, personal observation, however (albeit many years of personal observ. for that particular taxon).

For pelagic aquaflyers, specifics of shell reduction or expansion might be related to required forelimb excursions, as well as the specific bracing important for mirrored stroke utilization (I recommend taking a look at Stephen Godfrey's 1984 manuscript on plesiosaur locomotion and aquaflying).

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