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Re: Digits, Digits, Digits!!




Steve Brusatte wrote:

There is a relief pitcher on the Florida Marlina named Antonio >Alfonseca. Other than being an excellent closer, he also has six >fingers! [snip]
Many listmembers have commented that it would be very difficult to >provide enough mutations to create a totally new functional digit >after that digit has been lost (this was a response to me asking: why >didn't tyrannosaurs and other theropods re-evolve digits?). >Obviously, the mutations were there to create this totally new finger >for Alfonseca, as they were to create the sixth finger of philidor and >Jaime's cats.


I'm not particularly knowledgeable on the topic of the molecular basis of supernumerary digits (hyperdactyly). However, are you certain this trait is heritable? Will Mr Alfonseca's children have six fingers??

Maybe the extra digit results from a snafu during development, and not as a result of any mutated or duplicated gene.

In this case, a secondarily tridactyl tyrannosaur would be a "one-off", and could not become the first of a new lineage of three-fingered tyrannosaurs.


Tim


------------------------------------------------------------

Timothy J. Williams

USDA/ARS Researcher
Agronomy Hall
Iowa State University
Ames IA 50014

Phone: 515 294 9233
Fax:   515 294 3163

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