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

Re: Re-evolving bones?



Tracy Ford wrote:

>Horeses regrew there toes? Which hen's have teeth? Which bones so I may
>be enlightened?

I think it was clear what I meant. If the developmental potential is there,
we have good reason to suspect that the evolutionary potential is there.
For example, pseudogenes can be transcribed again, initiating cascades of
developmental processes that result in reversals. This has clearly been
demonstrated.

If we have no idea about the developmental potential of a specific
structure, it's fair to that say we cannot claim special knowledge of it's
evolutionary potential. Sure, that doesn't mean we should close our minds
to the possibility that it didn't happen that way, but to assume that it
just plain couldn't is pure speculation.

>So what happens when Paleontologist, nearly completely ignore a group
>of animals, Prosauropods from their cladagram, because they can't
>concive them being the ancessor? Clark, Perle and Norell, only mention
>a what Sereno,
> (only 6 things), and not do a detailed cladisitc anaylasis of
>Therizinosaurioidae and Prosauropoda? What would they have to loose? To
>COVER all the ground is the BEST way to be the MOST scientifically
>correct.

And the phylogeny you cite is from whose comprehensive phylogenetic
analysis? This is published (with a data matrix and character analysis) in
which peer-reviewed journal? Without invocation of special knowledge of the
genetic / developmental mechanisms underlying the evolution of
therizinosauroids? I haven't seen that one, but I'd like to.

Sure, paleontologists could be wrong about therizinosauroids; you could be
right. It certainly seems a little more intuitive to derive them from
"prosauropods", at least from a distance, but at a finer focus I'm not so
sure. I trust the characters and the methods more than my gut-feeling based
on a few phenetic resemblances. Most good paleontologists today won't be
easily convinced by scenarios that pretend to explain why things can't
evolve into other things by using incorrect information or speculative
stories. Makes good fantasy, but not good science.

It's paleontology after all, and part of what makes it challenging is
dealing with a relative dearth of data without crossing the line from the
realm of science into the realm of science fiction. Paleontologists
certainly don't have the same breadth of data that biologists studying
extant taxa do (they study extinct organisms), but they have the distinct
advantage of having a profoundly ancient chronicle of life to study. At
least that's the way I see it.

Sorry if I insulted anyone, but I speak from experience on this list: if
you get busted wandering off into wonderland, someone is bound to call your
bluff. The controversies surrounding the phylogenetic affinities of
therizinosauroids, alvarezsaurids, herrerasaurids, etc. are interesting
subjects, but they will be resolved by science, not just by gestalt.

                       --John R. Hutchinson