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

Mike Keesey wrote:

> I'm very confused, because what you just said sounds consistent with
> what Nick just said. And your second sentence seems to contradict
> itself.

I don't see how.  If Mesonychia is the sister taxon to a Cetacea+Artiodactyla 
clade (which Thewissen et al. call Artiodactyla, and you call Cetartiodactyla), 
then Mesonychia is equally close to whales and to crown Artiodactyla (which 
includes hippos).  Mesonychia precedes the basal split that led to the 
Raoellidae+Cetacea (your 'Pan-Cetacea') on the one hand and the crown 
Artiodactyla on the other.  Which is what you convey here...

> According to you, the topology is (Andrewsarchus, Mesonychia, (crown 
> Artiodactyla*, (Raoellidae, Cetacea))). 

Yes, exactly.  

> Therefore, cetaceans share a clade with hippopotami (and other [crown] 
> artiodactyls) which excludes
> mesonychians.

True.  Again, Nick said the same thing, and I agree with it.  But I disagree 
with the inference that this makes cetaceans *closer* to hippos than to 
mesonychians.  Just because Mesonychia is outside the least inclusive clade 
that contains whales and hippos does not necessarily make whales *closer* to 
hippos.  To use an analogous example, _Deinonychus_ is outside the least 
inclusive clade that contains _Archaeopteryx_ and _Passer_; but _Archaeopteryx_ 
is still *closer* to _Deinonychus_ than it is to _Passer_.  (Phew, I finally 
managed to work in something to do with dinosaurs!)  

> * which I think should just be called "Artiodactyla"

Yes, I think it's a nice idea to limit Artiodactyla to the crown artiodactyls.  
But as I said in a previous message, raoellids (but not whales!) have 
traditionally been put in crown Artiodactyla, as members of the Suina; so this 
might have been a factor in Thewissen &c's decision to favor a more inclusive 
Artiodactyla (i.e., including both raoellids and whales).

> Put it all on a tree:
> "Pan-Cetartiodactyla"
> |--Andrewsarchus
> |--Mesonychia
> `--Cetartiodactyla
>     |--Artiodactyla (incl. Hippopotamidae)
>     `--"Pan-Cetacea"
>         |--Raoellidae
>         `--Cetacea

You could also represent the topology this way...

      `--Artiodactyla (incl. Hippopotamidae)

or you could simplify it a bit:

      |--"Pan-Cetacea" (incl. raoellids, cetaceans)
      `--Artiodactyla (incl. Hippopotamidae)

Thus, the "Pan-Cetacea" (Raoellidae+Cetacea) is sister taxon to Artiodactyla.  
Under this scheme, and following you (M. Keesey), the name Artiodactyla is 
restricted to the crown Artiodactyla.  However, Thewissen &c use Artiodactyla 
for a more inclusive group - which you call Cetartiodactyla.  But this doesn't 
change anything.  The centrepiece of my argument was that Thewissen &c's 
phylogeny buries Whippomorpha.  There's no way you can reconcile their 
morpho/fossil phylogeny with any molecular phylogeny that includes a 
Whippomorpha/Cetancodonta clade.  If you defined Whippomorpha as the least 
inclusive clade that includes whales and hippos, Whippomorpha becomes the same 
(in content) as your Cetartiodactyla (Thewissen et al.'s Artiodactyla).


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