[Taxacom] dinosaurs and wolves

Stephen Thorpe stephen_thorpe at yahoo.co.nz
Wed Oct 3 15:38:20 CDT 2012

> In all cases, however, the authors note that the hypothesis of a single re-evolution of legs is more parsimonious than the alternative of multiple losses<
I worry that such statements take parsimony out of proper context of a *whole phylogeny*, and not just one aspect of the phylogeny, i.e., multiple losses of legs may be a feature of the most parsimonious overall phylogeny for snakes ...

From: Wolfgang Wuster <w.wuster at bangor.ac.uk>
To: Ken Kinman <kinman at hotmail.com> 
Cc: "taxacom at mailman.nhm.ku.edu" <taxacom at mailman.nhm.ku.edu> 
Sent: Thursday, 4 October 2012 7:06 AM
Subject: Re: [Taxacom] dinosaurs and wolves

On 03/10/2012 18:17, Ken Kinman wrote:


Pachyrhachis and relatives tend to float a bit, grouping variously as 
sister to the Macrostomata, within them, or slightly further out near 
the base of the Alethinophidia. In all cases, however, the authors note 
that the hypothesis of a single re-evolution of legs is more 
parsimonious than the alternative of multiple losses. Obviously, the 
most parsimonious solution is not *necessarily* the correct one, but at 
the end of the day we will have to await new fossil discoveries for more 
conclusive evidence.

The paper itself ("Assembling the Squamate Tree of Life: Perspectives 
from the Phenotype and the Fossil Record") is well worth reading, 
containing a host of new morphological characters, and also discussing 
the extreme lack of congruence between molecular and morphological data, 
particularly in relation to the position of the Iguania in squamate 


> Hi Wolfgang,
>      I haven't seen the newest phylogeny (by Gauthier et al., 2012), 
> but I assume that it further solidifies the general consensus that 
> Pachyrhachis and relatives are macrostomatan snakes (not sister group 
> to all snakes).  However, even that would not necessarily mean that 
> they re-evolved legs.  Isn't there also a general consensus that it 
> only indicates that snakes lost their legs numerous times (in 
> different lineages)?
>              -------------Ken
> ---------------------------------------------------------------------------------------------------------
> > Date: Wed, 3 Oct 2012 07:47:21 +0100
> > From: w.wuster at bangor.ac.uk
> > To: taxacom at mailman.nhm.ku.edu
> > Subject: Re: [Taxacom] dinosaurs and wolves
> >
> > On 03/10/2012 04:58, Ken Kinman wrote:
> > > Stephen,
> > > I didn't say anything about reversals requiring reactivation of 
> genes. I certainly know of no snakes or marine mammals reactivating 
> leg genes and the reinvention of legs.
> >
> > Actually, there is reasonable evidence that simoliophiid snakes
> > (Pachyrhachis, Haasiophis) may have re-evolved hind limbs, based on
> > their possession of these appendages and their nesting deep in the
> > ophidian phylogeny. See Gauthier et al., Bulletin of the Peabody Museum
> > of Natural History 53(1), April 2012.
> >
> > Wolfgang
> >
> >
> > --
> > Dr. Wolfgang Wüster - Lecturer
> > School of Biological Sciences Bangor University
> > Environment Centre Wales
> > Bangor LL57 2UW Wales, UK
> > Tel: +44 1248 382301 Fax: +44 1248 382569
> > E-mail: w.wuster at bangor.ac.uk
> > http://pages.bangor.ac.uk/~bss166/
> >
> >
> >
> >

Dr. Wolfgang Wüster  -  Lecturer
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Environment Centre Wales
Bangor LL57  2UW                Wales, UK
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