[Taxacom] The real story (53 million year rabbit foot)

Michael Heads michael.heads at yahoo.com
Sat Nov 19 13:05:01 CST 2011


Hi Ken,
 
That's good. I was a bit worried by your last sentence: 'Calling this a "rabbit-foot" is not particularly useful, especially if it is stem-Lagomorpha which
predates the origins of rabbits'. The minute a fossil is involved, everyone starts talking about stem groups. Why? There was never any suggestion that these fossils were stem group. So you'd agree that it's not parsimonious to assume a fossil is a basal (stem) member of its group?   
 
Michael
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: Sunday, 20 November 2011 6:05 AM
Subject: [Taxacom] The real story (53 million year rabbit foot)
 
Hi Michael, 
       I just read the article, and John got it all wrong (getting his
information from a news story).  But to answer your question first, I
did not assume that the fossil is basal (stem-lagomorpha).  Note that I
actually said that the important question is whether these foot bones
are early crown Lagomorpha OR stem-Lagomorpha.  And as you note, they
are the former.    

      Now for John's confusion.  Nowhere in the article does it say that

rabbits and hares diverged 35 million years ago.  It merely says that
these foot bones extended the fossil record of lagomorphs on the Indian
Subcontinent (the oldest had been 18 million years old, and these being
53 million years old, it extended the Indian Subcontinent's record by 35

million years).    

       And just to counter John's charge that the molecularists got it
wrong, take a look at Springer et al., 2003 (Proc. Natl. Acad. Sci.,
100:1056-1061).  Their Figure 2 (Molecular Time Scale) shows crown group

Lagomorpha (Leporidae splitting from Ochotonidae) originating at 50
million years ago.  The "rabbit" foot bones show that it was at least 3
million years earlier.  I could find noone having suggested that crown
group lagomorphs originating as late as 35 million years ago, and John
jumped to a erroneous conclusion based on an erroneous news story.  

      Actually, the 2003 molecular estimate of 50 million years is
pretty darn good considering that it was made 8 years ago, before all
these fascinating new lagomorph fossils started coming out of Asia.  So
thank you John for having unwittingly brought forward this case where
the molecularists did a darn good job.  
             ------------Ken                              
-----------------------------------------------------------
Michael Heads wrote:
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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