[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: New paper on fish fingers

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:

       `--rest (Rhaptochelydia if you like).

We'll see, though. :-)