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Re: Turtles and Crocodylians are not Reptiles - no? What are they?



On Thu, Jul 24, 2008 at 8:45 PM, Tim Williams
<twilliams_alpha@hotmail.com> wrote:
> If turtles and crocs are being drawn together by long-branch attraction, and 
> neither birds nor
> squamates can break this up, then all other options are exhausted.

Well, as I said few clades is not a big problem per se, it could be
problematic if there are many homoplasies - long-branch attraction is
an artifact resulting from homoplasies. It could be reduced by some
analytical techniques.

>> My fault here. Normally "fossil" DNA reffer to a conserved DNA
>> sequence - somewhat molecular fossil - it could help in somecases. But
>> what I've meant is what Boehm said: DNA preserved in fossil.
>
> This hasn't happened yet (for fossil vertebrates, anyway), except for certain 
> subfossil taxa.

Yes, that is the reason for I have said *eventually* and in parentheses.

>> Closer to hippos thant to mesonychids anyway.
>
> Actually, no.  Under Thewissen &c's phylogeny, there is a 3-way polytomy 
> (trichotomy)
> composed of Mesonychia, _Andrewsarchus_ and the Cetacea+Artiodactyla clade.  
> The
> hippopotamids are inside the crown Artiodactyla, in the Suina clade.  Because 
> the whales
> are recovered in a Cetacea-Raoellidae clade at the base of the Artiodactyla, 
> cetaceans are
> *not* closer to hippos than to mesonychians.  Not according to this 
> phylogeny, anyway.

As Pharris and Keesey noted, *closer* in a phylogenetical/hennigian
context: shared the same evolutionary history for a longer time.

[]s,

Roberto Takata