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Re: they keep on growing despite early fusion
-------- Original-Nachricht --------
Datum: Fri, 25 Jan 2008 08:58:44 -0600 (GMT-06:00)
Von: david peters <firstname.lastname@example.org>
> re: squamates. Anybody can discover what I did, just by plugging
> in taxa.
That sounds simple, but you're talking about a PhD thesis in terms of amount of
work. The fact that you expended far less effort than a thesis does not bode
well for the quality of your work.
> In fact, Benton 1985 nested pterosaurs next to lepidosaurs and far
> from archosaurs in the only published cladogram that had all three
> taxa included.
Do you mean this paper?
Classification and phylogeny of the diapsid reptiles, Zool. J. Linn. Soc. 84:
97 -- 164 (1985)
Because this one has Pterosauria as the sister-group to the rest of
Archosauromorpha (fig. 17 and p. 154).
Also note that it does not present a cladistic analysis. I don't know if the
computing power for a matrix with that many taxa was even available in 1985.
Instead, Benton presented subtrees (called "cladograms") and supplied a list of
apomorphies for each node, without trying to find out if his subtrees together
were in fact the most parsimonious tree that explains the data. There is no
data matrix, just those lists!
At the time, it was the most thorough treatment of the question that had ever
been made. For today's standards, it's _not even publishable_ in the form it
was published. (Even though the data -- the mentions of which character states
are present in which taxa -- must not be ignored in modern studies.)
Here's the section of the text on Pterosauria (pp. 134 and 136) in its entirety:
" Pterosaurs have typically been regarded as archosaurs that had their
ancestry among the thecodontians (e.g. Romer, 1966; Wellnhofer, 1978). However,
Wild (1978) has described two late [sic] Triassic genera on the basis of good
material (*Eudimorphodon*, *Peteinosaurus*), and he has made the proposal that
the pterosaurs arose directly from 'eosuchians' and are not true archosaurs.
Pterosaurs possess an antorbital fenestra, but Wild (1978: 247) considered that
this may be a convergence. Further, Wild (1978: 246â253) reviewed numerous
similarities between the early pterosaurs and various 'eosuchians' and
differences from early thecodontians. [Sounds phenetic to me.] The characters
shared with *Youngina*, *Prolacerta* and others are all primitive to diapsids
as a whole, except for the reduced quadratojugal, the ossified sternum, the
'hooked' 5th metatarsal [which is now considered an autapomorphy of the diapsid
crown-group, now that the younginiforms have been thrown out
of that clade], and the 3-pointed teeth seen in *Eudimorphodon*.
Pterosaurs display all of the characters of the Neodiapsida as far as can
be determined, except B2 (ventral processes on parietals) and B6 (emarginated
quadrate). [B is the list of autapomorphies of Neodiapsida.] They show some
archosauromorph synapomorphies (C4--10), but lack others: C1--3, 11--14.
Pterosaurs share two characters with the Lepidosauromorpha [including
Younginiformes]: the single ossified sternum, and specialized sternal
attachments for the ribs. The most parsimonious position for the pterosaurs at
present [based only on the mentioned characters!] is within the
Archosauromorpha, as sister-group of all other archosauromorphs. Further work
is needed on this question as well as on the [surprisingly ignorant] suggestion
that Pterosauria are the sister-group of Aves (Gardiner, 1982)."
My thesis supervisor's EndNote file only mentions one other "Benton 1985", and
that one is titled "Mass extinction among non-marine tetrapods". It's not
likely that he'd publish two big treatises in the same year on the same topic,
so I conclude the paper I quote above is what you mean and misremember. It is,
after all, the closest the pterosaurs have ever come to the lepidosaurs -- and
to the younginiforms! -- in a published paper.
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