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ID: Large Dinosaur Caudal Vertebra


BigJim2500

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I just bought a large, fairly well preserved vertebra from a rock shop in Tucson. It was found in the Aguja Formation in Texas, a formation that isn’t especially well researched. My diagnosis is that the vert is most likely theropod, and the only theropod that large that is in the area and comes to mind for me is the Acrocanthosaurus. This diagnosis is leaving me skeptical. Acro bones are pretty rare to my knowledge (there are only 5 articulated specimens discovered as of now), and I don’t see any documentation of them being found in Aguja, though as I said before it is not well researched. My only other theories are that this is from a Kritosaurus (which seems unlikely based on the size and shape), or that it is some other saurischian that isn’t documented in the formation yet. If I could at least get verification that it is theropod that would be very nice. This purchase will either have been a pretty good deal, or an absurdly amazing one. We’ll see, and thanks for helping!

 

Bone is 6.75” long, 4.5” wide at widest point, and 4.75” tall at tallest point.

F77C91E9-7A5A-40EB-97DE-C5B73ECB5E41.jpeg

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It's Aguja, so definitely not Acrocanthosaurus. Acrocanthosaurus is much older. Very little has been described from Aguja. It's a tail vert, but that's all I can say. Could be dromaeosaur, oviraptor,  ornithomimid, or  even a tyrannosaur. 

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Just a guess, but first impression is this is a sauropod caudal vertebra; otherwise may be a tyrannosaur caudal vertebra. I believe some daspletosaurid material is known from the Aguja.

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Thanks! I remembered that Acro is 80 and Aguja is more like 70 mya. I think there was daspletosaur described at one point, but this is so big it rules out anything that isn’t either very big theropod or sauropod.

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Are you sure it’s from the Aguja Formation?

Because it sure does look like a mid-caudal centrum of a diplodocid, or titanosauriform sauropod to me...

 

 

At almost 10 inches in length it looks to be too large for any theropod caudal vertebra once they start to elongate like this one. The largest caudal centrums in any Tyrannosaurs are the proximal caudals. And the centrums in that part of the tail are more like a boxy rectangle, if that. 

 

So my feeling is is that this is from a sauropod. If truly Cretaceous, than an indeterminate titanosauriform sauropod. There are reports of fragmentary remains of titanosauriform sauropods from Cretaceous beds in Texas. Many have been referred to Alamosaurus. But this may likely be an example of a known genus being used as a wastebasket for these indeterminate remains. 

 

Below are the tail vertebrae of a Japanese Cretaceous Titanosauriform sauropod called Tambatitanis amicitiae.

And then the proximal caudals of Tyrannosaurus rex, for comparison:

014CD579-0B88-4B9D-AF3B-7603F0EC7271.jpeg

777C8A65-AE81-4AC9-9AF3-D1D96A8D500B.jpeg

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4 hours ago, hxmendoza said:

Are you sure it’s from the Aguja Formation?

Because it sure does look like a mid-caudal centrum of a diplodocid, or titanosauriform sauropod to me...

 

 

At almost 10 inches in length it looks to be too large for any theropod caudal vertebra once they start to elongate like this one. The largest caudal centrums in any Tyrannosaurs are the proximal caudals. And the centrums in that part of the tail are more like a boxy rectangle, if that. 

 

So my feeling is is that this is from a sauropod. If truly Cretaceous, than an indeterminate titanosauriform sauropod. There are reports of fragmentary remains of titanosauriform sauropods from Cretaceous beds in Texas. Many have been referred to Alamosaurus. But this may likely be an example of a known genus being used as a wastebasket for these indeterminate remains. 

 

Below are the tail vertebrae of a Japanese Cretaceous Titanosauriform sauropod called Tambatitanis amicitiae.

And then the proximal caudals of Tyrannosaurus rex, for comparison:

014CD579-0B88-4B9D-AF3B-7603F0EC7271.jpeg

777C8A65-AE81-4AC9-9AF3-D1D96A8D500B.jpeg

Yeah, my thoughts exactly; this is a very large amphicoelous or amphiplatyan vertebra that morphologically looks like a distal titanosaur caudal (Tambatitanis is a good example). Alamosaurus was the first thing that came to mind, but the Aguja may be a bit older than it if I recall correctly.  

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Very little is described from the Aguja Formation and no Tyrannosaurids but its a similiar age as the Judith River of Montana so one would expect comparable dinosaurs.  This looks like a Titanosaurid vert like others have said.

 

I think hxmendosa asked the correct question is it from the Aguja formation?  A dealer at the tucson show who collects the Aguja also finds Javalina Fm material on his property at different exposures you just need to know where to look.  The Aguja underlies the Javalina a so it would not be out of the question to mix up the formation of material found.   Alamosaurus is described from the Javalina.  Unfortunately I cannot find any good pictures of preserved distal dorsals or caudals but have another Titanosaurid to look at.

 

I would like to see an end shot and straight on picture of you first photo not at an obtuse angle. 

 

 

Almosaurus appears to be a sister taxon to yes Mendozasaurus.  :o

 

Screenshot_20180502-043605.jpg.4ba1c76914dd756c5e6bd582bb737421.jpg

 

 

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14 minutes ago, Troodon said:

Very little is described from the Aguja Formation and no Tyrannosaurids but its a similiar age as the Judith River of Montana so one would expect comparable dinosaurs.  This looks like a Titanosaurid vert like others have said.

 

I think hxmendosa asked the correct question is it from the Aguja formation?  A dealer at the tucson show who collects the Aguja also finds Javalina Fm material on his property at different exposures you just need to know where to look.  The Aguja underlies the Javalina a so it would not be out of the question to mix up the formation of material found.   Alamosaurus is described from the Javalina.  Unfortunately I cannot find any good pictures of preserved distal dorsals or caudals but have another Titanosaurid to look at.

 

I would like to see an end shot and straight on picture of you first photo not at an obtuse angle. 

 

 

Almosaurus appears to be a sister taxon to yes Mendozasaurus.  :o

 

Screenshot_20180502-043605.jpg.4ba1c76914dd756c5e6bd582bb737421.jpg

 

 

 

Awww, how nice of them to name a sauropod after me!

A475A3C6-6ECB-4BB7-9A4B-2FEF6E289427.jpeg

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2 minutes ago, hxmendoza said:

 

Awww, how nice of them to name a sauropod after me!

 

I'm jealous 

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Troodon, 

 

I think that Alamosaur or similar titanosaur makes the most sense. The guy I got the bone from and the collector he got it from didn’t seem to know to much in regards to dinosaurs (they were the ones who guess Acrocanthosaurus), so it’s possible that the collector just found something in the general area and called it Aguja. Only reason I’m skeptical about that is that he did also have a dorsal vert from Agujaceratops, but it could be he just mixed some things up. Either way sense it seems to be titanosauriforme I still got a good price for it. I don’t think that there is any way it could be from somewhere like the Morrison, because it doesn’t seem like saying it’s from a formation that obscure would drive up the value in anyway.

 

I’ll get those photos to you soon, but looking at your pictures it seems like a strong match.

 

Thanks!

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That might also be a croc vert... have you looked into the tail of Deinosuchus?  

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Jpc,

 

I don’t think it’s crocodilian, those usually have a more pronounced difference between the socket on the back and the ball in the front. Pretty sure that this is dinosaur. Could be possible though, I haven’t seen a lot of known deinosuchus material.

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12 hours ago, jpc said:

That might also be a croc vert... have you looked into the tail of Deinosuchus?  

 

Doesn’t match up with any crocodilian dorsal or caudal verts. Plus there is no rounded end on the centrum as seen on Deinosuchus caudals or other crocodilians.

 

Croc dorsals have mostly square shaped dorsals and though the mid-distal caudals

Start to elongate. If took this very as a Deinosuchus caudal, and extrapolated, then this Croc would be ridiculously too big. Deinosuchus grew to between 25 and 33 feet.

 

Below are pics of Deinosuchus verts. The centrums don’t match. 

 

This is is definitely a Titanosauriform Sauropod caudal centrum.

 

36E4F969-30E2-4218-9970-E668C778F33A.jpeg

BAD0C56A-545A-403F-A49D-B06567E2633A.jpeg

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eudygesllifernakristlanthc.jpg

 

 

edit:oops,same imagery as previous poster.Apologies to all concerned,will let it stand because of the map of D. dsitribution

 

 

 

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3 minutes ago, doushantuo said:

eudygesllifernakristlanthc.jpg

 

Again, the centrums don’t appear to match match up. Plus these illustrated centrums are only 5 inches in length. The centrum in question is almost twice that.

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i am not into identication,HXM.

And do i know what the axial vertebrae of Mendozasaurus look like?

maybe:P

 

 

 

 

 

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Also, the neural arch and complex tend to shift forwards (roster ally) on titatanosauriform sauropods as the vertebral centrum in question also appears to show.

15F2C1B5-DFC5-408E-8EA1-B36BA345E98A.jpeg

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3 minutes ago, doushantuo said:

i am not into identication,HXM.

And do i know what the axial vertebrae of Mendozasaurus look like?

maybe:P

 

 

 

I wasn’t calling anyone out. Just kept adding more info. Sorry if you misunderstood my intention. 

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Thanks for the Deinosuchus pix.  I have some Eocene croc tail verts that are totally  flat on the ends... no ball and socket like the dorsals.   

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Definitely agreeing with hxmendoza here. Both for the reasons I stated before and that this hypothetical deinosuchus seems like it would be record breaking-ly large if this was is tail vert. Thanks for the suggestion though!

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