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RE: Turtles and Crocodylians are not Reptiles - no? What are they?
Robert Takata wrote:
> Sure. And all fossil represent only a fraction of diversity that had
> ever existed too. Few taxa could be more problematic if we have much
I think you're missing the point. When it comes to Sauropsida/Reptilia, it's
not just that the vast majority of species have gone extinct, but the vast
majority of major clades as well. 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.
> 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
> 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.
Mike Keesey wrote:
> Wouldn't it be better to restrict Artiodactyla to the crown and just
> say that cetaceans are not artiodactyls; but are their extant
> sister group;, and raoellids are very basal stem-cetaceans.
That would seem to be a very good idea. Artiodactyla could be restricted to
the crown artiodactyls; Cetacea could similarly be restricted to the crown
cetaceans, and another name (Cete?) could be used for Cetacea and
stem-cetaceans (raoellids, 'archaeocetes'); and the name Cetartiodactyla could
be co-opted for the least inclusive clade that includes artiodactyls and
cetaceans. However, raoellids have traditionally been considered artiodactyls
(as members of the Suina clade), so this may have influenced Thewissen &c's
decision to keep Raoellidae inside Artiodactyla (and pull Cetacea along with
To be honest I don't know how Artiodactyla, Cetacea, and Cetartiodactyla are
each currently defined. Thewissen &c studiously avoided the term
'Cetartiodactyla', even though it's an obvious choice for the
Cetacea+Artiodactyla clade. This may have something to do with the fact that
the Cetartiodactyla concept came about from molecular analyses (just a guess).
> No Whippomorpha. Kind of sad....
Not to me. :-) I never bought the entire Whippomorpha (=
Hippopotamidae+Cetacea) thing anyway - despite what (some) molecular
phylogenies said. BTW, there are some people who favor(ed) a
Hippopotamidae-Cetacea clade, but hate(d) the name 'Whippomorpha', and so came
up with a new name: Cetancodonta.
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