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Re: Alamosaurus as biggest North American sauropod
----- Original Message -----
From: Jaime Headden <email@example.com>
> The best strategy, in my opinion, is to simply do away with crap taxa.
Well then, I look forward to your paper on the subject.
> I prefer the use of type specimen comparison over any other process so far
used to "assess" the _reasonableness_ of a "genus"'s validity, including but
not limited to ontogeny, stratigraphic and geographic distribution.
Right. Pick one. Only idiots would try to assess all the available data.
>Morphologic comparison, placed first and foremost, assures us that degree of
>unique features can affirm characters distinguishing organisms.
It's common in your posts to see your writing descend into incomprehensible
gobbledegook when you are just making stuff up (sometimes, whole words). This
sentence makes no sense. how do you be assured of something in science? do you
now what hypothesis testing is?
>At this point, ontogeny can only inform,
> and stratigraphy and geography can only expand or reduce the range of the
> taxon, rather than provide real evidence to distinguish taxa in the absence
> of other data.
I give up trying to figure out what you're saying here.
> The weight of the latter points can increase with age and distance, such as a
> ceratopsian from the Oldman Formation (Alberta, Canada) and one from the
> Judith River Formation (Montana, USA) [ignoring the Two Medicine Formation
> for the moment as it is effectively an extension of the JRF]
I am guessing that you don't actually understand what a clastic wedge is, or
how basin flexure affects deposition.. or in fact, very much at all outside of
taxonomy, but do go on...
>; when the two are morphologically similar, enough so that features may be
>ontogenetically or individually variable when compared to the same range in
>other taxa, provenance and horizon are irrelevant.
Nope. I am guessing you haven't actually studied ontogenetic and stratigraphic
effects on morphology. Or maybe you will surprise us all with some insightful
h that you write.
(I gave up on the rest of that paragraph as it was just garbage; hypothetical
> As it is somewhat common to note, the holotype of *Alamosaurus sanjuanensis*
>is apparently based on a juvenile, and it lacks distinctive characteristics
>permitting it's segregation from other particular titanosaurs.
Non-mature. I am generally uncomfortable with anything other than mature and
non-mature since people's interpretations of these terms vary, but we can say
juvenile (I probably do elsewhere). Further, body size variation is generally
undocumented in dinosaurs, such that relative size may not be a very reliable
indicator of relative age.
Anyway, Wilson spoke about the holotype scapula at SVP2011. I think, if you
want to get to the bottom of this problem, answer this: are sauropod specimens
found in the North Horn and Javelina Formations (ie. outside of the type
stratum: the Naashoibito) referable to Alamosaurus using any kind of parsimony?
>As the lack of reasonably complete material for the taxon exists,
Not really. if you think that the Texas and Utah material is referable then
there is quite a bit of material.
> and that large sauropod skeletons are difficult to find in the latest Late
> Cretaceous of southern Laramidia
The super-giant biggest material yes, but smaller material is pretty common.
Which, if you read the press release, you would know.
(Gave up again on the remaining convoluted text).
I'll agree that maybe we should have written c.f. Alamosaurus in the paper, but
the text explains in detail the rationale behind the referral. Even Wilson now
agrees that there is no evidence for more than one taxon of sauropod in the US
Jaime A. Headden
The Bite Stuff (site v2)
"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)
"Ever since man first left his cave and met
fferent 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, 9 Dec 2011 11:25:23 +1100
> From: firstname.lastname@example.org
> To: email@example.com
> Subject: Re: Alamosaurus as biggest North American sauropod
> Matthew Martyniuk <firstname.lastname@example.org> wrote:
> > I don't see the issue with using parsimony. In fact I have kind of an
> > issue when people don't use it. If the remains can't be differentiated
> > from _A. sanjuanenis_, and there is no evidence to suggest multiple
> > taxa were present in this environment, it should be considered _A.
> > sanjuanenis_ until evidence to the contrary can be produced.
> As a rule of thumb, this "rule" is unevenly applied. For example,
> Carpenter and Tidwell (2004) referred all sauropod material from the
> Arundel Formation to a single taxon. All the Arundel sauropod
> material was consistent with the presence of a single species, which
> took the name _Astrodon johnsoni_. In the process, _Pleurocoelus
> nanus_ and _P. altus_ were considered to be subjective junior synonyms
> of _Astrodon johnsoni_, a taxon that was originally established on
> material that is not diagnostic at the genus level (tooth + tooth
> On the other hand, Wilson and Upchurch (2003) did *not* combine
> _Titanosaurus indicus_ and _Antarctosaurus septentrionalis_ into a
> single taxon in their revision of the titanosaur material from the
> 'Sauropod bed' of the Lameta Formation at Bara Simla. This was
> despite the fact that this study found no reason to recognize more
> than one species at Bara Simla. The Conclusion makes this clear:
> "The discussion above, however, demonstrates that
> Huene & Matley’s (1933) decision to separate the
> ‘Sauropod bed’ specimens into several individuals
> from two taxa is not supported by the available
> evidence. It is possible that
> present, as originally suggested by Matley (1921).
> Even if more than one individual is represented,
> two or more taxa cannot yet be reliably distinguished.
> However, although morphological and geological data
> do not argue against the presence of a single species
> at Bara Simla, there is simply no positive evidence
> supporting this hypothesis."
> Because _T. indicus_ was based on material (two caudal vertebrae) that
> Wilson and Upchurch (2003) found to be non-diagnostic at the genus
> level, these authors declared _T. indicus_ to be a nomen dubium. _A.
> septentrionalis_ had been previously assigned its own genus
> (_Jainosaurus_; Hunt et al., 1994), which was the name adopted by
> later studies for the "valid" titanosaur from Bara Simla (e.g., Wilson
> et al., 2009, 2011 - the latter study assigned additional titanosaur
> material from a separate site [Chhota Simla] to _J. septentrionalis_
> ). However, I'm confused as to why all the titanosaur material from
> Bara Sima wasn't simply assigned to a single taxon that carried the
> name _T. indicus_, with _Jainosaurus septentrionalis_
> (=_Antarctosaurus septentrionalis_) as a junior synonym.