[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: Vancleavea campi - what is it? - not an archosauriform.
As descendants of the sister to Petrolacosaurus, thalattosaurians are
definitely diapsids with a reversed temporal condition, same as Araeoscelida
and mesosaurs and a bunch of others with absent lower temporal bars.
The antorbital fenestra goes with Dakosaurus, not above named taxa, but you
apologized earlier for that.
If you're not sure what I mean about thalattosaurians, check out the previously
listed refs. It's all there ready to test.
On Dec 5, 2009, at 4:00 AM, Jaime Headden wrote:
> David, I am not sure what you mean about thalattosaurians, but
> thalattosaurus (from *Askeptosaurus* to *Dakosaurus*) possess both
> supratemporal fenestrae as well as antorbital fossa and fenestrae. The former
> feature makes thalattosaurs (if non paraphyletic) firmly ensconced with the
> diapsid condition, and therefore members of Diapsida. If, as previously
> argued, you think the diapsid condition cannot reverse to the anapsid
> condition, this should be pretty firm evidence for placement of thalattosaurs
> (again, if nonparaphyletic) within Diapsida (but don't take my word for it,
> read the Rieppel works instead). The latter feature is a common argument for
> archosauriform phylogeny, and does not seem to occur outside of it (based on
> the common occurance of crania with the fenestra to be found instead the
> structure assumed to be Archosauriformes by its definition).
> Jaime A. Headden
> "Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)
> "Human beings, who are almost unique in having the ability to learn
> from the experience of others, are also remarkable for their apparent
> disinclination to do so." --- Douglas Adams (Last Chance to See)
> "Ever since man first left his cave and met a stranger with a
> different language and a new way of looking at things, the human race
> has had a dream: to kill him, so we don't have to learn his language or
> his new way of looking at things." --- Zapp Brannigan (Beast With a Billion
>> Date: Fri, 4 Dec 2009 21:59:07 -0600
>> From: firstname.lastname@example.org
>> To: email@example.com
>> Subject: Vancleavea campi - what is it? - not an archosauriform.
>> One of the reasons why Vancleavea campi does not have an antorbital fenestra
>> and upper temporal fenestrae is because it is not an archosauriform. It is a
>> askeptosaurid thalattosaur and a sister taxon to the short-snouted
>> Miodentosaurus. [Links below]
>> The scales are still weird.
>> The neomorph bone between the orbits is nothing more than the ascending
>> process of the premaxilla.
>> For those who still think you have to stare at a specimen in person to
>> publish on it, well, now you see how that can prove to be a wee bit myopic.
>> David Peters
>> Cheng, Y.-N., X.-C. Wu, T. Sato. 2007. A new thalattosaurian (Reptilia:
>> Diapsida) from the Upper Triassic of Guizhou, China. Vert PalAsiatica 45:
>> Nesbitt, S. J., M. R. Stocker, B. J. Small and A. Downs. 2009. The osteology
>> and relationships of Vancleavea campi (Reptilia: Archosauriformes).
>> Zoological Journal of the Linnaean Society 157, 814-864.
>> Parker, W G. & Barton, B. J. 2008. New Information on the Upper Triassic
>> archosauriform Vancleavea campi based on new material from the Chinle
>> Formation of Arizona. Palaeontologia Electronica 11 (3); 14A: 20p.
>> Wu, X.-C., Y.-N. Cheng, T. Sato and H.-Y. Shan. 2009. Miodentosaurus brevis
>> Cheng 2007 (Diapsida; Thalattosauria): Its postcranial skeleton and
>> phylogenetic relationships. Vertebrata PalAsiatica 47:1-20.
> Windows Live Hotmail is faster and more secure than ever.