Re: New paper on fish fingers

[David Marjanovic <david.marjanovic@gmx.at>]

> > Maybe it is to be expected that new clades with major
> > morphological novelties will arise from "bushes" in which there
> > has been extensive "experimentation."

My impression is rather that such chaos rules everywhere, not just at the 
origin of arbitrarily selected "major morphological novelties". That has to 
be expected -- natural selection goes into whatever direction the 
environment determines, and few environments are seriously stable. Compare 
any two analyses of the same dinosaur clade... hadrosaurs for example... off 
the top of my head, a non-dino example is the origin of Permian 
captorhinids, which corresponds to nothing spectacular at all 
morphology-wise, yet there are two taxa (*Protocaptorhinus* and 
*Rhiodenticulatus*) that switch places from any phylogenetic analysis to the 
next.

> Indeed.  As another example... how else can you explain the situation in 
> early turtle evolution?  You have two Late Triassic forms (_Odontochelys_ 
> and _Chinlechelys_) which show strikingly different morphologies of the 
> dorsal carapace, with both interpreted as incipient.

Not really. I see just three differences: *Odontochelys* lacks sutures 
between the costal plates, appears to have more fusion between the ribs and 
the costals (though it's squished flat, while *Chinlechelys* is not...), and 
*Chinlechelys* shares with more derived turtles the condition of having the 
dorsal ribs articulate at the boundaries between the vertebrae rather than 
on a single vertebra. In sum, I predict that my thesis will find:

--+--*Odontochelys*
 `--+--*Chinlechelys*
    `--+--*Proganochelys*
       `--rest (Rhaptochelydia if you like).

We'll see, though. :-)