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

Re: ORNITHOMIMID THERIZINOSAURS



Matthew Troutman wrote
>Actually, I think that Pete decided that therizinosaurs are 
>bullatosaurian ornithomimid relatives, [...]
        Ok, I'm feeling a little left out here. George and I have been very
good boys and not cluttered the list with our "oviraptorsaur" versus "no way
they're theropods" threads for a long time, and this is what we get for it?
I think we've put in enough time for at least an honorable mention. :)

>The most recent, thorough analysis of this idea was Sues' 1997 _JVP_ 17:4 
>description of _Chirostenotes_.  However, I think that the analysis was very 
>flawed because of its poor coding, retention of function-related characters, 
>and characters that are found in few members of a taxon.
        I would be interested in your line-item appraisal of the dataset. As
for function-related characters, as long as they do not overweight a
function (e.g. four characters describing bipedality), there's nothing wrong
with them. A good way to test for overweighting is to see if characters
seemingly related to each other always occur with the same character states
in the same taxon. If they do, they may be linked. However, there is nothing
wrong with function-related characters in and of themselves.
        Characters found in too few members of a taxon? What's wrong with
this? Do you mean lots of "?"s in the dataset, or only a few "1"s? either
way, it hardly matters. Data are data, as long as they aren't autapomorphies...

>(The analysis also found Dromaeosauridae and Troodontidae sister-groups, 
>something that I think makes the cladogram suspect).
        Because we all KNOW that they aren't after all...
        Dr. Holtz is a smart guy, and I like his work, but personally I am
not going to go badmouthing somebody's analysis just because it doesn't
agree with Holtz 1994(a)! There is some evidence to support this tree
topology, you know... something about a hyperextendable digit II... :)

>I still stick by the position that therizinosaurs are ornithomimid relatives 
>based mainly on the braincase features (the inflated parabasiphenoid for one). 
        It is not a difficult position to defend, after all. :)

Peter Buchholz wrote:
>To date, no cladistic analysis has shown that therizinosaurs do NOT fall
within 
>Theropoda.
        I know George will say this, so I think I'll try to beat him to the
punch: has there been a cladistic analysis designed specifically to test
this assignment?

>I do not wish to have this become a debate between George, Tracy, Jon
>(Wagner), and I. 
        There! Finally, some credit for the scrapes and hard feelings... ;)
 
>Jon Wagner still apparently thinks my name is spelled with a T
        Aw jeez! I haven't misspelled the boy's name in four months, but he
has to go dragging this up again. Fer cryin' out loud Pete, don't you have
some obscure asian hypsilophodont to read about?

>I had previously spoken to Jaime privately about the posibility that perhaps
>oviraptors and therizinosaurs were sister groups within the Ornithomimosauria.
        As a quick aside, basal maniraptorform phylogeny is in such flux
that it is probably best represented by a trichotomy of Maniraptora,
Ornithomimisauria, Troodontidae, Tyrannosauridae, Therizinosauroidea, and
Oviraptorsauria (did I forget anybody?). Mix and match to your heart's
content, and wait for the next Holtz monograph... hopefully it'll be out
before the next Star Wars movie (nice safe time fram for you there...).

>There are a lot of weird features of the basal ornithomimosaur that suggest
        *Which* basal ornithomimisaur?

BTW: Thanks to whomever dug up the Oviraptorsauria definition...
        :)
        Wagner
----------------------------------------------------------------------------
    Jonathan R. Wagner, Dept. of Geosciences, TTU, Lubbock, TX 79409-1053
                    "...To fight legends." - Kosh Naranek