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RE: Arboreal Theropods: The prize at the bottom of the cracker jack box






>Yes, good point. Still, 3my is a lot of elephant generations, too. You'd
>think there'd at least be a change in average crown height before that!
>
>Jason Brougham
>Senior Principal Preparator
>American Museum of Natural History
>jaseb@amnh.org
>(212) 496 3544
>
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>On 7/24/13 11:57 AM, "Mike Keesey" <keesey@gmail.com> wrote:
>
>>Whoops, meant to reply to the list.
>>
>>On Wed, Jul 24, 2013 at 8:56 AM, Mike Keesey <keesey@gmail.com> wrote:
>>> On Tue, Jul 23, 2013 at 6:19 PM, Jason Brougham <jaseb@amnh.org> wrote:
>>>>
>>>> Some on this thread have mentioned that, if an animal is using trees
>>>>in its biology, it should show specializations.
>>>>
>>>> Recent work has found an ingenious way to test the time between a
>>>>behavioral shift and a clear morphological specialization.
>>>>
>>>> In fossil proboscideans that switched from a tree leaf diet to a grass
>>>>diet (as marked by carbon isotope ratios) the answer is 3 million
>>>>years.
>>>>
>>>> I bet that is a long interval but, then again, tooth crown height
>>>>should increase faster (by shifting to the taller end of the
>>>>pre-existing distribution of tooth crown heights in the population)
>>>>than complete descent and reversal of a toe.
>>>>
>>>> 
>>>>http://www.nature.com/nature/journal/vaop/ncurrent/full/nature12275.htm
>>>>l
>>>
>>> That's really cool! But consider that basal eumaniraptors probably had
>>> much shorter generation times (not to mention more offspring) than
>>> proboscideans.
>>>
>>> --
>>> T. Michael Keesey
>>> http://tmkeesey.net/
>>
>>
>>
>>-- 
>>T. Michael Keesey
>>http://tmkeesey.net/
>