Source of urban legend about the 1916 AMNH Tyrannosaurus rex mount?

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Russell Engelman

May 29, 2024, 6:08:55 PMMay 29
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I had a question regarding the history of the first mount ofTyrannosaurus rex, the famous one the AMNH put up back in the 1910s. This is something I had heard a few times when I was much younger and still getting started in paleontology, but now that I am older and want to take another look at it am having trouble tracking it down.

So, supposedly the story goes that when the first mount of Tyrannosaurus rex was being created at the AMNH in 1916 H.F. Osborn deliberately padded out its length to make it 50 feet (15 m) long. According to the storyteller, he did this for two reasons...
  1. Osborn wanted to say the AMNH had found the largest carnivorous dinosaur ever. While T. rex was already large he wanted to be able to say it was substantially larger than already known taxa like Allosaurus, Ceratosaurus, "Epanterias", etc., so there was no doubt in anyone's mind who had the largest theropod.
  2. Fifty was a nice, round even number that made the size of T. rex easy to remember by the public.
The exact wording I had heard was when the AMNH preparators asked Osborn how long the mount was supposed to be he told them to "just keep adding caudal vertebrae until it was exactly 50 feet long". So the AMNH T. rex was reconstructed with an...ahem...generous amount of plaster caudal vertebrae. Not necessarily beyond the scope of reason but still a bit eyebrow-raisingly long given what was known at the time.

The story ends with Newman (1970) figuring out the last 12 feet or so of the tail of the famous AMNH mount were plaster, based at least in part on the fact that complete skeletons of Gorgosaurus didn't have a tail anywhere near as long. He excluded the plaster part of the tail and all of a sudden you get a T. rex capable of balancing horizontally over its hips. As a result, many museums quietly changed their displays from stating the length of T. rex as 50 feet to 40 feet (12 m), until the discovery of extremely large individuals of T. rex like Sue and Scotty bumped that up to 45 feet (~14 m).

I had heard this many years ago in casual conversation with other paleontologists, but when I actually tried to find a source documenting this story I couldn't find anything. I could find Neuman (1970) well enough, but not the part about Osborn padding out the length of T. rex intentionally to make it look more impressive. It certainly sounds like something H.F. Osborn would do but "sounds likely" is not the same thing as "actually happened". It's not hard to find sources for Osborn wanting to be able to say he had the largest carnivorous dinosaur of all time, but whether he would go so far as to fudge the numbers is murky. The first place I looked was on the Extinct Monsters blog, since that is usually a good place for anecdotes about Osborn, but I couldn't find anything on that story specifically. I am wondering if I might have seen it on one of those blogs on museum science from the golden age of paleo-blogging now lost to the Internet, like Chris Norris' Prerogative of Harlots. I was wondering if anyone knew a source for this apparent urban legend?


May 30, 2024, 6:50:15 AMMay 30
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Have you contacted Jane P. Davidson?  I know she specialized in Cope, but she may know something about this Osborn story.

Jacqueline Silviria

May 30, 2024, 2:14:31 PMMay 30
to Russell Engelman,
Good morning,

Frustratingly, I’m having trouble finding primary sources on the preparation and mounting of AMNH 5027 beyond Osborn’s accounts. The short lay-reviews by Burger (2015) and Miller (20152022) either don’t mention Hermann’s plaster tail at all or seemingly don’t add much to what Newman observed.

Bob Evander might know something, given he wrote an article on Hermann’s destructive techniques (Evander, 2009). I can provide his contact info upon request.

On a related note, I’m also having trouble finding the origin of Brown’s "king of the period and monarch of its race” quote that was featured in The Ultimate Guide to Tyrannosaurus Rex (1996)Wikipedia cites Dingus & Norell (2010) rather than a primary source.


Jacqueline S. Silviria
The Last King of the Jungle

Department of Earth & Space Science
University of Washington
Seattle, WA, USA

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Ben Creisler

May 30, 2024, 3:39:38 PMMay 30
Ben Creisler

The Barnum Brown quote is from 1915, unless he used the phrase earlier:

Barnum Brown (1915)
Tyrannosaurus, the largest flesh-eating animal that ever lived
American Museum Journal 15(6): (270) 271-279


Pg. 274:
Tyrannosaurus is a giant reptile distantly related to lizards, crocodiles and birds. Its hind legs are formed like those of birds and the bones are pneumatic. It was a powerful creature, doubtless swift of movement when occasion demanded speed, and capable of destroying any of the contemporary creatures, a king of the period and monarch of its race.

Gregory Paul

May 30, 2024, 3:58:47 PMMay 30
That Osborn was a notorious white elitist racist and eugenist very likely has a lot to do with his terminology of racial dominance applied to the Tyrant Lizard King -- although 5027 is not a T. rex;  probably too early and its low postorbital bosses are not at all like the much taller and more prominent Mickey Mouse ear like discs of T. rex Scotty and Tufts-Love. 


Russell Engelman

May 30, 2024, 10:49:28 PMMay 30
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"Have you contacted Jane P. Davidson?  I know she specialized in Cope, but she may know something about this Osborn story."

That is a good idea. I will try that.

"Frustratingly, I’m having trouble finding primary sources on the preparation and mounting of AMNH 5027 beyond Osborn’s accounts. The short lay-reviews by Burger (2015) and Miller (20152022) either don’t mention Hermann’s plaster tail at all or seemingly don’t add much to what Newman observed."

That is what I noticed as well. I wonder if the information might be somewhere in the AMNH archives? The museum keeps a lot of information around on its activities and expeditions. I highly doubt Osborn would openly remark about the caudal vertebrae in internal documents, but it's possible given so many people at the museum seemed to have disliked him (e.g., Edwin Colbert) that one may have mentioned it afterwards. I did read Roland Bird's Bones for Barnum Brown, but unfortunately it seems to be mostly focused on other aspects of the AMNH.

Thomas Richard Holtz

May 31, 2024, 9:24:50 AMMay 31
By the way, you referenced The Monster's Bones in the initial post. While it is an entertaining read, some of it is historically inaccurate, especially with regards to the science of the times, the sequence of discovery of Tyrannosaurus fossils, and related matters. I briefly cover this in my review in the Quarterly Review of Biology 


Thomas R. Holtz, Jr.
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Dept. of Geology, University of Maryland

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                        Thomas R. Holtz, Jr.
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Wendell Ricketts

May 31, 2024, 12:02:21 PMMay 31
A few books came to mind:

Preston’s Dinosaurs in the Attic

Lance Grande’s Curators

Hone’s Tyrannosaur Chronicles

Fortey’s Dry Storeroom No. 1

I haven’t read any of these recently, so offer them only as possibilities. I know Fortey’s book is about the British Museum, but he might have mentioned it in passing.



Ben Creisler

May 31, 2024, 3:02:21 PMMay 31
Ben Creisler

Ben Creisler

Various sources state that 50 caudal vertebrae were average for theropods. I don't have the original source for this idea, though. Note that SUE was found with 36 caudals but restored with 47.

Here's what Osborn has to say about the length of the tail in T. rex, restored with 53 caudals, the last 20 being "conjectural":

Henry Fairfield Osborn (1916)
Skeletal Adaptations of Ornitholestes, Struthiomimus, Tyrannosaurus
Bulletin of the American Museum of Natural History 35(Art. 43): 733-771
Pg. 770

Caudal vertebra (Fig. 17, Plate D). The anterior caudal, C1 (Fig. 17), partly unites by its caudal rib with the horizontally expanded internal plates of the ilium (Fig. 17, Amer. Mus. 5027). The caudal series so far as preserved in the specimen (Amer. Mus. 5027) is represented in the shaded vertebræ figured in Plate D, namely C1-C 15, C 17, ?C 21-22. The intermediate vertebræ as well as the terminal vertebræ, C 23-53, are conjecturally restored. As in other carnivorous dinosaurs the caudals gradually diminish in size and increase in relative length. The centra are amphiplatyan or slightly procœlous. Neuro-central sutures are observed in Cd 2, Cd 11. The tail is an elongate balancing organ for the anterior part of the body, having considerable flexibility and exhibiting no indications of the extreme rigidity observed in the inflexible tail of the Ornithomimida.

Mickey Mortimer

Jun 3, 2024, 4:34:00 AM (12 days ago) Jun 3
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Well if you consider theropod specimens known at the time with fairly complete tails, I think there's only the Ceratosaurus type which is estimated to have 51 caudals (only one missing).  Poekilopleuron has 21 preserved, Allosaurus' neotype 33, Ornitholestes 27, Compsognathus 15, Eustreptospondylus has 12 that might get us out to caudal 21, 13 in Podokesaurus, 17 in Struthiomimus AMNH 5339...

So fifty caudals would probably be perfectly reasonable, especially if you're comparing other large theropods without the elongated distal vertebrae of Ornitholestes, Podokesaurus or Struthiomimus.

Mickey Mortimer

Jun 4, 2024, 4:02:15 PM (10 days ago) Jun 4
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Comments from Jane P. Davidson, who is not currently a member of the DMG.  Posted with permission from Dr. Davidson.

“I think we have some blending of stories here.  I would ask your reader to read my discussions in ‘The Bone Sharp’ (1997), ‘A History of Paleontology Illustration,’ and ‘Patrons of Paleontology,’ all by me.
Osborn for example knew perfectly well that the animal was not bipedal in the 1912 mounting.   Since you can buy gummy bipedal specimens today a story goes a long way.”

“I do not think there is anything to Osborn competing with extra vertebrae.  Nobody knew what they were doing anyway. The position of bipedal they knew was wrong right along.  If someone wants to contact me that is fine.” (
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