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

Re: Reevolving bones?

Dinogeorge wrote:
>>What cartilaginous metatarsal I? Name one other vertebrate that has a
>>cartilaginous metatarsal I!
        According to Ostrom 1969, reiterated in Holtz 1994(b), _Deinonychus

>>         Name them (I know you can). Has it occured to you that some of these
>> "reversals" might be part of the same reversal either developmentally or
>> funcitonally?>>
        I'm sure there is jargon for this somewhere.
        "Developmentally": In this case, I mean homoplaisy which coems about
as a result of the developmental pattern of another, adaptive homoplaisy. A
simple example might be if whales redeveloped legs for mating. They might
not need kneecaps, but the kneecap might go along part-in-parcel with the
leg (don't nobody flame me on this, I don't know anything about whale kneecaps).
        "Functionally": In this case, I mean a homoplaisy which results from
a reversal to an ancestral state followed by convergence for similar
purposes. FOr example, if yon whales redeveloped their legs for walking,
they might reduce their tail. It would then appear as though they possesed
two reversals (tail reduced, legs) when they really have a reversal and a
convergence. Weak example...

>         Horse droppings...>>
>What kind of comment is this? Are you trying to elevate the level of this
>discourse or something?
        An inappropriate one. I withdraw the remark. Sorry.

>So are segnosaurs maniraptorans? Maniraptoriforms?
        No to the first, yes tot he second.

>So are segnosaurs dromaeosaurs? What's a dromaeosaur, anyway?
        No. I was not making a comment about phylogeny. You stated:
"There's the problem of the segnosaur pelvis. It looks nothing like a
theropod pelvis:"
        I was merely listing ways in which it *does* look like a theropod

>This is a clear segnosaur apomorphy. Cladists should care.
        Cladists look at SYNapomoprhies to elucidate phylogeny.
>So are segnosaurs oviraptorids? Ornithomimids? I thought they were
        Probably form a clade with oviraptorsaurs.

>><< >Reversals are a red flag in phylogenetic analysis--a signal that
>>something may
>> >have gone wrong in the analysis.
>>        You have *NO* theoretical basis for making this claim.>>
>Sure I do. Or is cladistics infallible after all??
        No. As John Hutchinson and I have gone to great pains to point out,
there is nothing inherently wrong with a reversal.

>         Let's all flip to the systematics channel, shall we?>>
>What kind of comment is this?
        A spurious and disrespectful on. Ignore it, please.
>><< >Using a computer program that simulates evolution
>>         Can we really do this? Forgive, but I rather thought that if we
>> could do this, I wouldn't have to go to grad school. >>
>You obviously have no idea about what I'm talking about here, do you? Back to
>square one, if you please.
        What I meant was, we do not understand how evolution works, and I'll
bet some would suggest that we ccould not ever write a program which will
acccurately reflect evolutionary patterns. If this is the case, any program
we design will be a product of the model which created it, and may not
accurately reflect evolutionary processes. The results of your test will be
skewed based on the programmer's biases, and may not reflect the power or
lack thereof of cladistic methodolgy. Still, it would be interesting, I guess...
      Jonathan R. Wagner, Dept. of Geosciences, TTU, Lubbock TX 79409
      "The cost of living hasn't affected its popularity." - Unknown