[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: Pleurocoelus question
On Tue, 12 Jun 2001 23:47:37
Tompaleo wrote:
>In a message dated 6/12/01 9:00:51 PM Eastern Daylight Time,
>dinoland@lycos.com writes:
>
>>
>> Okay, fine, but who is to say that Astrodon is a nomen dubium. I was just
>> talking about this with Ray Stanford off list (feel free to jump in, Ray
>:-).
>> I've done a lot of reading on the early discoveries of this dinosaur for a
>> project during the past week or so.
>
>So have I and many others, both on and off this list, and over a
>considerably longer time ;-)
Oh, yeah, I'm just getting started. That's why I turned to all of you experts
on the list :-)) I just wish that there were some dinosaur-bearing deposits in
Illinois. I'll just have to stick to brachiopods for awhile, I guess.
>> To me, the species is diagnostic, unless tooth evidence does not count...
>> >
>
>BINGO! In the case of sauropods, it does not! Sauropod teeth in general are
>not distinct enough for taxonomic distinction. The "Astrodon" form is a
>general form expressed by other genera not necessarily related to it. Though
>star shaped in x-section, it is still a peg like in overall shape which
>might indicate basal titanosaur or brachiosaur.
I do realize that its general shape is still peg-like. However, I agree with
Ray. Somebody should try to conduct a study on the cross section of these
sauropod teeth, at least in brachiosaurids, and see how prevalent this star
shape is. Like Ray, I also don't doubt the fact that the star shape may be
widespread, but we'll never known until somebody does some research.
Matt Wedel refers to the
>"Astrodon" morph as a "form genus" . I can see why, I have also seen and
>recovered these _exact_ shaped_teeth from the Antlers Fm. of Oklahoma (home
>of _Sauroposeidon_) and in the Cloverly Fm. of MT (along with a considerable
>number of postcrania and verrts of a yet to be described sauropod that are
>NOT pleurocoelus sensu Pleurocoelus sp.) If the teeth from these localities
>were mixed in with my Arundel material, it would be impossible to distinguish
>them! But it is a near certainty that they belong to entirely different
>genera.
That's interesting. If you find some time and don't mind "destroying"
perfectly fine specimens, cut a few of them up and examine them under a
microscope!
>
>Additionally, regarding the Maryland taxon, _P. altus _ (Marsh) was named for
>the material belonging to a larger (ie. more adult) sauropod than that which
>belonged to the smaller (more juvenile)_P. nanus_. Virtually all who have
>seen the material, including myself, recognize the likelhood that the two
>represent ontogenetic variants on the same Pleurocoelus sp.(?) theme. Alas,
>the teeth we now refer to as Astrodon, likely belonged to Pleurocoelus
>(likely _altus__ ) INMHO.
I haven't seen the specimens, but I have seen pictures. Pleurocoelus is a
small sauropod, which is where some of the confusion may have stemmed from.
>
>Conclusion: All sauropod material from the Arundel should now be referred to
>Pleurocoelus, and _P._altus_ at that - the more valid nomen.
This may very well be true, and would make sense. But, I still abide by my
first post, and think that some sort of study should be done. If somebody
shows me evidence that Pleurocoelus, and other brachiosaurids, have these
star-shaped cross sections, I will then forget about Astrodon!
>
>Finally, all of the above represents a turn around in my thinking regarding
>Astrodon. I used to regard the "Astrodon" problem much the same way you do
>now Steve. But with recent discoveries, and work by Salgado, Wedel and
>others, and my own pers. obs., I have seen the light. My "Maryland Pride"
>has been humbled!
You may very well be right, but show me the papers! Honestly, I think that
Pleurocoelus and Astrodon are poor choices for state fossils, especially
Pleurocoelus. Texas would have been much better off designating Brontopodus,
or maybe Eryops.
Steve
---
***************************************************************
Steve Brusatte-DINO LAND PALEONTOLOGY
SITE: http://www.geocities.com/stegob
ONLINE CLUB: http://clubs.yahoo.com/clubs/thedinolanddinosaurdigsite
WEBRING: http://home.wanadoo.nl/dinodata.net/
INTERNATIONAL LANGUAGE SITE: http://www.geocities.com/stegob/international.html
****************************************************************
Get 250 color business cards for FREE!
http://businesscards.lycos.com/vp/fastpath/