Jump to content

Recommended Posts

Could someone help me with the identification and position of this vertebra.  I was thinking it was procoelous and maybe crocodylomorph?  Scale bar = 1mm.

 

SmallVertLabeledComposite.thumb.jpg.d074fca4e493d1609eeff319eee37abf.jpg

  • I found this Informative 2
Link to post
Share on other sites

Not a croc.  Crocs have real ball and socket ends to their verts... at least buy the late Cretaceous they do.  And the squarish bottom edge is not crocky.  I have some like this as well, and I do not know what to call them... turtle maybe.  This is a caudal, I am pretty sure I see attachments for chevrons in the ventral view.  

  • I found this Informative 4
Link to post
Share on other sites

I would lean toward a Baenidae type turtle.  That what I call the ones in my collection.

 

Screenshot_20170315-121513.thumb.jpg.50832553d9c2ea5687234aa678b698f2.jpg

  • I found this Informative 6
Link to post
Share on other sites

Thanks very much @jpc and @Troodon for helping me wade through this Hell Creek material.  So it sounds like I should label the vertebra as "cf. turtle caudal vertebra (Baenidae?)".  Here are a couple eroded verts of what I have labeled crocodylopmorphs (also Hell Creek).  It sounds like I should expect similar strong convexity on the socket on all vertebrae in the spinal column of a croc.

 

HellCreekCrocVerts.thumb.jpg.11adffce79a39af1e1785f6cad3c4f2a.jpg

 

Thanks again for your help.

Link to post
Share on other sites

Agreed.  Here is some supporting documentation from Tom Carrs unpublished book.  Sorry quick phone images from when I saw the book this past collecting season.

 

20160917_045354.jpg.0e20ceaafc29210e09e1eb504a33eeb8.jpg

  • I found this Informative 2
Link to post
Share on other sites

Whoa... wait a minute here... Tom Carr's unpublished book!!??  I want one.  What is it?  a field guide to late K  bones?  

Link to post
Share on other sites
20 minutes ago, jpc said:

Whoa... wait a minute here... Tom Carr's unpublished book!!??  I want one.  What is it?  a field guide to late K  bones?  

 

It was to come out in the fall but looks like it's late, ha ha 

 

 

 

Link to post
Share on other sites

Thanks, I had missed that one.  I am both a pro (museum) and a private collector, and I believe nanotyrranus is a valid genus.  I am confused if I should get the book or put it down immediately.    

Link to post
Share on other sites
37 minutes ago, jpc said:

Thanks, I had missed that one.  I am both a pro (museum) and a private collector, and I believe nanotyrranus is a valid genus.  I am confused if I should get the book or put it down immediately.    

I'm with you,  he's missed the boat on that one but there may be a few things in there worth seeing.  Let see what the finished product looks like and price.

Link to post
Share on other sites
48 minutes ago, Troodon said:

I'm with you,  he's missed the boat on that one...

 

 

There are others besides Carr that are not on the "Nano Wagon"; Brochu, Brusatte, Holtz, to name a few.

 

 

 

Link to post
Share on other sites

Yes there are a few naysayers  but there is a much longer list of notable theropod paleontologists that support the species.  Everyone is entitled to their opinion and that is what makes science tick.   I've listened to both sides of the argument, spoken personally to paleontologists that have examined the complete skeleton not just the skull and not that I'm an expert but have have examined it myself and have come away with my opinions.  That's more than most who have an opinion on this subject.

  • I found this Informative 2
Link to post
Share on other sites
5 minutes ago, Troodon said:

Yes there are a few holdouts but there is a much longer list of notable theropod paleontologists that support the species.

 

 

Without consensus the issue remains unsettled.

If Nanotyrannus is valid, why are we still waiting for a hidden cache of juvenile T. rex specimens to be discovered?

 

 

Here is a portion of a Stephen L. Brusatte book review of Peter Larson's book: “Tyrannosaurus rex, the Tyrant King”
 
"As a tyrannosaur systematist, I was particularly annoyed that the book completely lacks cladistic studies or robust quantitative analyses of any kind.  Furthermore, it is clear from the tone of many chapters that several authors are staunch believers in the validity of Nanotyrannus, the so-called pygmy tyrannosaur that has been thoroughly discredited as a juvenile Tyrannosaurus based on careful consideration of ontogeny and variation (Carr, 1999; Carr and Williamson, 2004).  Nowhere in the book do authors provide a firm rationale for re-erecting Nanotyrannus as a valid taxon, despite the fact that the onus is them to argue against the thoughtful arguments of Thomas Carr and colleagues.  The one specific feature that is constantly stated as a ‘key’ character separating Tyrannosaurus and Nanotyrannus is tooth count, specifically that the latter animal has more teeth than adult Tyrannosaurus. However, Carr and colleagues have interpreted this difference as ontogenetic variation: teeth are lost during growth.  In his chapter on variation, Larson asserts that no extant animal loses teeth throughout ontogeny, but provides no citations to back this strong claim.  Not only that, but Carr (1999:table 2) actually provided concrete evidence that Albertosaurus, a close relative of Tyrannosaurus, loses teeth throughout ontogeny.  These data are rarely cited by proponents of Nanotyrannus, which befuddles me."

 

  • I found this Informative 1
Link to post
Share on other sites

I've added some additional comment to my prior post.  I'm not sure you will ever get consensus to many ego's at work...

 

 

Link to post
Share on other sites
1 hour ago, Troodon said:

Yes there are a few naysayers...

 

 

The number of opponents vs proponents is not as lopsided as you suggest.

Actually, there are quite a few naysayers, six (6) in fact, on this recent paper.  

 

Brusatte, S.L., Carr, T.D., Williamson, T.E., Holtz, T.R., Hone, D.W., & Williams, S.A. (2016)

Dentary groove morphology does not distinguish ‘Nanotyrannus’ as a valid taxon of tyrannosauroid dinosaur. Comment on:“Distribution of the

dentary groove of theropod dinosaurs: Implications for theropod phylogeny and the validity of the genus Nanotyrannus Bakker et al., 1988”.

Cretaceous Research, 65:232-237

 

 

The million dollar question remains: If Nanotyrannus is valid, where are all the juvenile T. rex specimens hiding?

 

  • I found this Informative 1
Link to post
Share on other sites
Susan from PA

There is a juvenile T.rex out there, Baby Bob.  Once the Dueling Dinos and Baby Bob are studied by the Paleontological world, this matter will finally be put to rest.  They hold the key to this whole debste.  I've read as much as I can, or have access to on this debate, and I do believe, as others do, that Nanotyrannus is a valid genus.  I would love them to be one and the same, as I have lots of Nanotyrannus fossils in my collection, but that is not going to happen.  

  • I found this Informative 1
Link to post
Share on other sites

The Hell Creek Formation is noted for poor preservation of theropod skeletons.  Very few,  outside of adult Trex's, have been found and juvenile specimens are unheard of.  So finding juvenile specimens of any species is not something that is typically expected, it's the Hell Creek.  Juvenile and infant Rex isolated bones have been found and are available for study from the Black Hills Institute and infant teeth are common and I have lots in my collection.  Like Susan mentioned Baby Bob is a confirmed baby Rex skull and along with the Dueling Dino's needs to be studied.

 

Aside from the need or desire to see juvenile Rex specimens in the end that's not what will describe the genus.  The postcranial skeleton of the Dueling Dino's is all that is needed to do that.  Those arms are so different that its is a slam dunk.  Susan reminded me how different the 3D braincase are between Nano and Rex's. 

  • I found this Informative 1
Link to post
Share on other sites
FossilDudeCO

@Peat Burns

A turtle vert from Hell Creek is pretty cool!

I'd be stoked to have that in my collection!

  • I found this Informative 2
Link to post
Share on other sites
33 minutes ago, FossilDudeCO said:

@Peat Burns

A turtle vert from Hell Creek is pretty cool!

I'd be stoked to have that in my collection!

Thanks FossilDudeCO!  Yes, I love it anytime I can add to my collection a new taxon for a site / formation or a new element of a taxon (like turtle verts in addition to just shell fragments).  I also love how such additions increase the value of the collection for reference and comparative work.  People think I'm nuts when I get excited about obscure brachiopods, etc. :)

 

(P.S. I'm also enjoying the Nanotyr. Vs. T. rex debate.  I had the privilege of seeing "dracorex" before it was revealed and find these ontogenetic vs. separate species investigations interesting).

Link to post
Share on other sites
FossilDudeCO

Haha, yes I am enjoying it as well, but I don't know enough to comment either way! 

 

  • I found this Informative 1
Link to post
Share on other sites

Ehhhh my take on the nano debate is that like 80+% of theropod specialists favor the juvenile rex hypothesis. Speaking of, I just saw the beautifully preserved juvenile T. rex "Jane" at the Burpee Museum just about a week ago - the only "nano" that has been studied histologically and determined to still be rapidly growing.

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...