The Missouri Tyrannosaur

[Joseph Fossil]

In a previous post, I discussed if Tyrannosaurus rex (Tyrannosaur, Western North America) (Late Cretaceous 68-66 Million Years ago) was able to colonize Eastern North America as the Western Interior Seaway retreat by the early Maastrichtian (I received excellent feedback from other four members, notably @Troodon, that this was prevented by the KT Mass Extinction event 66 Million Years ago). As a result, I don't believe Tyrannosaurus rex was able to effectively colonize Eastern North America (as far as I'm currently aware).

 

However, looking over some records of Late Cretaceous Tyrannosaur fossils, I do believe that a Tyrannosaurid (Yes a Tyrannosaurid) was able to colonize part of Eastern North America in the area of what is today Chronister well, Bollinger County, Missouri! Not much is known about this Tyrannosaur genera, but here is the info I could find on it!

 

Unnamed Tyrannosauroidea genus (Tyrannosaur) (McNair Sand Member of the Ripley Formation-Missouri, US, North America) (Late Cretaceous, 70-66 Million Years ago)

(Size unknown)

http://www.fossilworks.org/cgi-bin/bridge.pl?a=collectionSearch&taxon_no=38606&max_interval=Cretaceous&country=United States&state=Missouri&is_real_user=1&basic=yes&type=view&match_subgenera=1

 

https://www.lakeneosho.org/Ozarks/Chronister2.html

 

https://www.sos.mo.gov/CMSImages/Publications/symbols/dinosauressay.pdf

 

 

Photographs of the Chonister well Tyrannosaur specimens have also been tricky to find, the only ones I've found were shown during an August 2016 Science in St. Louis Seminar series lecture by Geologist Dr. Micheal Fix, Ph.D., Associate Teaching Professor, Department of Physics of University of Missouri-St.Louis titled Monster in the Hollow: The Story of Missouri's Ozark Dinosaurs.

 

 

 

 

 

 

The presentation also showed a photograph of a decent sized Dromeaosaurid tooth from the same site in Missouri!

 

 

 

[Joseph Fossil]

What I'm wondering is based on the photographs shown, can a guess on the overall size of the Missouri Tyrannosaur genera be extrapolated and are there any features in the specimen that can help determine if it's just a member of Tyrannosauroidea or part of the more advanced Tyrannosaurid?

 

Also, can an overall size for the Missouri Dromeaosaurid be extrapolated based on the tooth size?

 

@Troodon What do you think?

[Troodon]

Sorry cannot help much

On the surface that bone does not look like theropod.  The tooth is not really in focus to say much....  Cannot even determine if that tooth belongs to a Dromaeosaurid other than being small, not very recurved and cannot see the other carina or base profile.   You cannot determine size looking at teeth, they vary with position and are constantly being replaced and can be unerupted.

[jpc]

I also don't see theropod in that bone.  

[Joseph Fossil]

On 4/28/2023 at 1:00 PM, Troodon said:

Sorry cannot help much

On the surface that bone does not look like theropod.  The tooth is not really in focus to say much....  Cannot even determine if that tooth belongs to a Dromaeosaurid other than being small, not very recurved and cannot see the other carina or base profile.   You cannot determine size looking at teeth, they vary with position and are constantly being replaced and can be unerupted.

 

@Troodon That's ok! Thanks for the input though, I really appreciate it!

 

Won't lie though, kinda disappointed that there isn't more information available on this Missouri Tyrannosaur (The lack of photographs - with the ones above being the ONLY ones I could find after a year's worth of searching - is just bizarre). You would think that who ever discovered these remains would want it published and publicized on a wider basis. Tyrannosauroidea fossils (especially anything else besides the occasional fossil tooth) are pretty rare in Eastern North America and Tyrannosaurid fossils in the region are almost unheard of. 

 

I looked and I couldn't even find museum catalog numbers for these specimens, despite being discovered all the way back in 1945 and erroneously being labeled as Albertosaurus sp. fossil remains. It would be expected that at least after so much time, someone would at least have given the specimens a museum catalogue number by this point?

 

 (E. B. Branson, 1942.) Dinosaur from the Cretaceous of Missouri. Bulletin of the Geological Society of America, 53:1841

 

(C. W. Gilmore, 1945.) Parrosaurus, n. name, replacing Neosaurus Gilmore, 1945. Journal of Paleontology, 19:540

 

I'll see what else I can find on these specimens, but this whole thing is just confusing on why more data ins't available on this potentially ground backing discovery in the field of Eastern North American Tyrannosaurs?

[Joseph Fossil]

On 4/28/2023 at 1:24 PM, jpc said:

I also don't see theropod in that bone.  

 

@jpc It's hard to tell, but I do see some Theropod characteristics in the leg bone (mainly the hole structure of the inside and its slight narrowness). But I have to be honest, it's so fragmentary it is very very hard to tell without taking a real close look at it. Also, the photographs of the leg bone could've been much better and more close up (I'm also frustrated the lectures didn't explain what part of the leg this fossil bone comes from)?

 

Have any guesses?

[Joseph Fossil]

6 minutes ago, Joseph Fossil said:

 

@Troodon That's ok! Thanks for the input though, I really appreciate it!

 

Won't lie though, kinda disappointed that there isn't more information available on this Missouri Tyrannosaur (The lack of photographs - with the ones above being the ONLY ones I could find after a year's worth of searching - is just bizarre). You would think that who ever discovered these remains would want it published and publicized on a wider basis. Tyrannosauroidea fossils (especially anything else besides the occasional fossil tooth) are pretty rare in Eastern North America and Tyrannosaurid fossils in the region are almost unheard of. 

 

I looked and I couldn't even find museum catalog numbers for these specimens, despite being discovered all the way back in 1945 and erroneously being labeled as Albertosaurus sp. fossil remains. It would be expected that at least after so much time, someone would at least have given the specimens a museum catalogue number by this point?

 

 (E. B. Branson, 1942.) Dinosaur from the Cretaceous of Missouri. Bulletin of the Geological Society of America, 53:1841

 

(C. W. Gilmore, 1945.) Parrosaurus, n. name, replacing Neosaurus Gilmore, 1945. Journal of Paleontology, 19:540

 

I'll see what else I can find on these specimens, but this whole thing is just confusing on why more data ins't available on this potentially ground backing discovery in the field of Eastern North American Tyrannosaurs?

 

@Troodon Also, forgot to add this reference.

 

(B. L. Stinchcomb, 2006.) Chronister vertebrate site. In D. Hoffman, B. L. Stinchcomb, and J. R. Palmer (eds.), Association of Missouri Geologists, 53rd Annual Meeting and Field Trips, Sikeston, Association of Missouri Geologists, 5-8

 

 

The only other fossil sites I've found so far that may hold Tyrannosaurid fossils in Eastern North America (and these maybe just misidentified Appalachiasaurus fossils) are the Campanian aged Cape Fear River Mileboard 56 in North Carolina (with Tyrannosaur remains there being erroneously labeled as Gorgosaurus sp. fossil remains) and the Tar Heel Formation Campanian aged Phoebus Landing, Black River in North Carolina.

 

http://www.fossilworks.org/cgi-bin/bridge.pl?a=collectionSearch&taxon_no=53193&max_interval=Cretaceous&country=United States&state=North Carolina&is_real_user=1&basic=yes&type=view&match_subgenera=1

 

(H. W. Miller, 1967.) Cretaceous Vertebrates from Phoebus Landing, North Carolina. Proceedings of the Academy of Natural Sciences of Philadelphia, 119:219-23

 

http://www.fossilworks.org/cgi-bin/bridge.pl?a=collectionSearch&collection_no=57918

 

(D. Baird and J. R. Horner, 1979.) Cretaceous dinosaurs of North Carolina. Brimleyana, 2:1-28

 

 

I'll try to look into the fossil remains from these other two sites and let you know what I find (the second one maybe promising, one of the authors of the paper describing the site is none other than renowned and brilliant Paleontologist Jack Horner, University of Montana). Maybe the fossil remains of tyrannosaurs here are more well studied than those at Missouri!

 

[Joseph Fossil]

Here's a link to the Cretaceous fossils of Phoebus Landing, North Carolina Paper!!!

 

https://digital.ncdcr.gov/digital/collection/p16062coll9/id/22621