"Celebrating the Richness of Paleontology through Fossil Hunting"

fossilera logo


The Bizarre Discovery and Rediscovery of the most famous dinosaur!

Article written by: Jayson Kowinsky -

Discovery of Tyrannosaurs rex

The author holding the Holotype fossil of Tyrannosaurus rex, CM 9380 (AMNH 973), at the Carnegie Muesuem of Natural History in Pittsburgh.
No, I didn't drop it!

Discovery of T. Rex - The first fossil Tyrannosaur Dinosaur

Like most things in science, Tyrannosaurus rex's discovery is not straight forward; it was actually discovered and independently named 3 different times!

1. The first time T. rex was discovered... But it doesn't count!

Othniel Marsh, in the back center, posing in 1872 with his fossil assistants armed with guns. Marsh and Cope were arch rivals during the Bone Wars. They would go as far as blowing up each others fossil finds with dynamite. This is Image is Public Domain in the U.S.

The discovery of T. rex begins during the Bone Wars of the late 1800's. In 1892, during the heat of the bone wars between Edward Cope's and Othniel Marsh's fossil hunting armies, Cope discovered two partial vertebra. He haphazardly studied them and made the assumption they came from a new ceratopsid dinosaur. He named it "Manospondylus gigas", which means "Giant Porous Vertebra." Cope then continued his frantic and reckless pursuit of dinosaur specimens and this new beast was all but forgotten for over 100 years.

Onward to over 100 years later... In 2000, Peter Larson from the Black Hills Institute found the spot where the original Manospondylus gigas was discovered. They excavated and found more of the original animal. Larson realized the animal Cope described over one hundred years ago is a T. rex!

Since "Manospondylus gigas" is the actual first T. rex discovered, the name T. rex would normally be deemed invalid and all T. rex's would become M. gigas. However, the International Code of Zoological Nomenclature (ICZN), which has the rules to naming animals, did an update in 2000. Any name that has been published enough and has been considered valid for 50 years can't be replaced by an older name. Since, T. rex fits these rules, the "tyrant lizard king" dinosaur will not be renamed.

1892 specimen found by Cope: "Manospondylus gigas". At the time, the two vertebra were not diagnostic enough to determine they were from a large dinosaur theropod.

2. The second time T rex was discovered. This is the one that counts!

This vintage photo is from 1905, Barnum Brown is shown in the white shirt working in the Hell Creek quarry in Montana where he found the holotype. This is Image # 28767 from the American Museum of Natural History

After the bone wars of the late 1800's was winding down, fossil hunters continued quenching the public's thirst for dinosaurs. Museums were still looking for trophy specimens to mount. Fossil hunters like Barnum Brown and Charles Sternberg rushed to collect specimens for major museums. In 1902 Barnum Brown, working for the American Museum of Natural History (AMNH), was led to some bones eroding out of the earth by a local land owner. These bones turned out to be something not seen before near Hell Creek in Montana. It was a large theropod with a huge skull and giant teeth. It took a full 3 years to excavate the beast. In 1905 when it was fully excavated (all 10% of it), Barnum transported the specimen to Osborn, the paleontology curator at the AMNH. There, Osborn studied and described it. He named it Tyrannosaurus rex (Tyrant Lizard King). It is specimen AMNH 973, and is now the holotype specimen for T. rex.

The reconstructed holotype was displayed at AMNH for a few years, until larger and more complete ones were found. It eventually got packed away and placed into storage. In 1941, when the United States entered WWII, the holotype T. rex was sold to the Carnegie Museum in Pittsburgh to protect it from being bombed by the Germans in New York (which was a real possibility). The holotype was then renamed CM 9380. This reconstructed specimen is still on display at the Carnegie Museum of natural history. They have no plans to ever move it. This fine holotype is pictured at the bottom of this article.

3. The other other first time T. rex was discovered. This one really should have been the real first one that counts... if it wasn't for a page number!?!?

This is a photo of Barnum Brown from 1914 in Montana. He is wearing his flashy fur coat, which he often wore to the dinosaur dig sites. This image is Public Domain in the United States.

Barnum actually discovered another T. rex two years before his discovery of the holotype specimen. However, due to not sending it to AMNH in a timely manner, and a small mistake by Osborn, it ended up not being the first official T. rex.

In 1900, Barnum was doing excavations in Wyoming, looking for a trophy Triceratops skull for the AMNH. There, he discovered a large carnivorous theropod, that was around 13% complete. Instead of shipping this intriguing fossil back to New York, Barnum continued looking for a trophy Triceratops skull. When he finally shipped it back the AMNH, Osborn saved it for a paper on "Tyrannosaurus and Other Cretaceous Carnivorous Dinosaurs" that would be published in 1905. In this paper, the 1902 specimen was also described. Unfortunately, Osborn thought the specimen found in 1900, labeled AMNH 5866, was from a different carnivorous dinosaur. He named this dinosaur Dynamosaurus imperiosus the "Imperial Powerful Lizard". The main reason for thinking it was a different animal was there were ankylosaur armor plates found with the specimen. He thought this specimen was covered in armor plates. In fact, the armor plates found with the specimen were probably the stomach contents of this tyrannosaur.

Later, after the paper was published, Osborn realized Tyrannosaurus was actually the same animal Dynamosaurus. As nomenclature rules go, the name of the specimen in the first publication is used. However, since both specimens were published in the same paper, the page numbers were used to determine the correct name of this type of animal. The 1900 specimen was described a pages after the 1902 specimen. Thus, even though Dynamosaurus was found first, Tyrannosaurus became the official name. Dynamosaurus is now lost to the annals of history, and Tyrannosaurus is a house hold name... all due to a page number.

Jaw section of the 1902 specimen found by Barnum Brown: "Dynamosaurus imperiosus". Osborn thought it was from a different dinosaur carnivore than the 1905 specimen, and named it Dynamosaurus imperiosus. A year later he realized it was from the type of animal the 1905 specimen came from; a T. rex.
These images are Public Domain in the United States


Thus ends the story of the first T. rex, or the first 3 T. rex's.
Luckily, T. rex has its nice, easy sounding name... If it wasn't for Cope rushing and not further excavating the "Manospondylus" dig site, or no one noticing a forgotten bone for over 100 years, or Barnum not sending the "Dynamosaurus" specimen back to New York in a timely manner, or because "Dynamosaurus" just happened to be placed a few pages after "Tyrannosaurus" in a publication, we are left with the name "T. rex"... the name that almost wasn't!

1905 Holotype found by Barnum Brown; CM 9380 (AMNH 973): "Tyrannosaurus rex". This historic photo shows the holotype T rex dinosaur specimen at the Carnegie Museum. It was reconstructed with with an incorrect upright posture. Image Credit: Carnegia Museum of Natural History

This is the Holotype of Tyrannosaurus rex, CM 9380 (AMNH 973), as it's currently mounted at the Carnegie Muesuem of Natural History in Pittsburgh. The holotype is now mounted in a much more accurate possition.

Recommended Tyrannosaur Books and Fossils:

The Bone Hunters: The Heroic Age of Paleontology in the American West
This book gives an overview of american paleontology and its beginnings with Thomas Jefferson. It concentrates on the 19th century paleontologist rivals O.C. Marsh and Edward D Cope. It's a quick read and recommended to anyone with an interest in the 19th centruy bone wars!

Tyrannosaurus rex, the Tyrant King (Life of the Past)
Peter L. Larson, Kenneth Carpenter (Editors), 2008

This is one of the best Tyrannosaurus rex books out there. It is a collection of everything T. rex, from it's range based on stratigraphy, why it has short arms, to soft tissue reconstruction. It includes many tables, drawings, and photographs. The book also comes with an accompanying CD. The CD has loads of images and animations, including a simulation of the famous T. rex, Stan. This is a wonderful resource for all things T. rex! The book is, however, very technical and not for the casual audience. If you are a T. rex enthusiast, this book is for you.

Elenco Science Tech T-Rex Skeleton 36" Scale Replica Model
This is a 3 foot, true to scale, Tyrannosaurus skeleton with 51 realistic pieces. This is one of the most realistic replicas I have found on the internet. It's an awesome educational piece for any T-rex fanatic, young or old!

Get An Authentic Tyrannosaurus rex Tooth:

T. rex is so popular it's hard to imaging you can actually have a real tooth from one! Tyrannosaurus teeth are not that common. Usually you can find teeth from its distant cousin Carcharodontosaurus for sale. However, Fossil Era has a selection of real Tyrannosaurus teeth. Check 'em out!

References / Works Cited

Rothschild, B. M. & Molnar, R. E. (2008) Looking again at the forelimb of Tyrannosaurus rex. In: Tyrannosaurus rex, the tyrant king. Larson, P. & Carpenter, K. (eds.). Indiana University Press. Bloomington, IN. pp.287-304.

About the Author

Contact Us

To ask Questions about Paleontology, Fossil Identification, Image Use, or anything else, email us. is very active on Facebook, you can also message us there!

We don't buy or sell fossils, so please don't email us asking about the value of a fossil or fossil purchases.

Visit us on Social Media:

Enjoy this website?
Consider a Paypal / Credit Card donation of any size to help with site maintenance and web hosting fees:

Privacy Policy and Legal Disclaimer

Back to the TOP of page

© 2000 - 2023 : All rights reserved


fossilguy logo is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to