[Taxacom] 53 million year rabbit foot

Michael Heads michael.heads at yahoo.com
Fri Nov 18 22:00:14 CST 2011


Hi Ken,
 
Why assume that the fossil is basal (stem-lagomorpha) just because it's a fossil? In fact, the authors concluded that the fossil wasn't stem group, and it indicates that 'diversification within crown Lagomorpha and possibly divergence of the family Leporidae were already underway in the Early Eocene'.
 
Michael Heads


Wellington, New Zealand.


My papers on biogeography are at: http://tiny.cc/RiUE0
Information on my new book, 'Molecular panbiogeography of the tropics', is at: http://www.ucpress.edu/book.php?isbn=9780520271968



________________________________
 From: Kenneth Kinman <kennethkinman at webtv.net>
To: taxacom at mailman.nhm.ku.edu 
Sent: Saturday, 19 November 2011 4:38 PM
Subject: Re: [Taxacom] 53 million year rabbit foot
 
Hi John,
      I think your conclusion that this contradicts molecular data may
be a bit exaggerated, and I'm not even sure the authors of the study
were correctly quoted.              

      In any case, whether the rabbits and hares diverged about 35
million years ago (although even you should be the first in line to
question that date), the origin of crown Lagomorpha is no doubt older
than that.  Anyway, the important question is whether these foot bones
are early crown Lagomorpha or older stem-Lagomorpha.  In the case of
stem-Lagomorpha, your comments would be totally inappropriate, and even
vis-a-vis early crown Lagomorpha, it's uncertain.      
      
       Not a case that I would point to as a grand failure of molecular
dating (although even I might be somewhat suspicious of the 35-milion
year figure).  On the other hand, you seem to jump onto it like it is a
total failure of molecular dating.  I suggest that the dating MIGHT need
some minor recalibration.  But in such cases, you seems prone to
reactionary exaggeration. Calling this a "rabbit-foot" is not
particularly useful, especially if it is stem-Lagomorpha which predates
the origins of rabbits.    
            -----------Ken                              
----------------------------------------------------------

John Grehan wrote: 
      Here's a recent example of an older fossil predating the molecular
date. Note their comment that " previous fossil and molecular data
suggested that rabbits and hares diverged about 35 million years ago". 

John Grehan 

Good Luck Indeed: 53 Million-Year-Old Rabbit's Foot Bones Found 
One day last spring, fossil hunter and anatomy professor Kenneth Rose,
Ph.D. was displaying the bones of a jackrabbit's foot as part of a
seminar at the Johns Hopkins University School of Medicine when
something about the shape of the bones looked oddly familiar. 
That unanticipated eureka moment has led researchers at the school to
the discovery of the oldest known record of rabbits. The fossil evidence
in hand, found in west-central India, predates the oldest previously
known rabbits by several million years and extends the record of the
whole category of the animal on the Indian subcontinent by 35 million
years. 
Published online in the February Proceedings of the Royal Society
<http://royalsociety.org/> , the investigators say previous fossil and
molecular data suggested that rabbits and hares diverged about 35
million years ago from pikas, a mousy looking member of the family
Ochotonidae in the order of lagomorphs, which also includes all of the
family Leporidae encompassing rabbits and hares. 
But the team led by Johns Hopkins's Rose found that their rabbit bones
were very similar in characteristics to previously unreported Chinese
rabbit fossils that date to the Middle Eocene epoch, about 48 million
years ago. The Indian fossils, dating from about 53 million years ago,
appear to show advanced rabbit-like features, according to Rose. 
"What we have suggests that diversification among the Lagamorpha
group-all modern day hares, rabbits and pikas-may already have started
by the Early Eocene," says Rose, professor in the Center for Functional
Anatomy and Evolution 



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