Tyrannosaurus rex is the quintessential dinosaur. However, its discovery and initial description have been clouded by legends and fanciful stories. Letters, field notebooks, reports, published descriptions, field photographs and even receipts, have been consulted to reveal to a true as possible story about the discovery and subsequent description of the first Tyrannosaurus rex.

In 1897, Henry Fairfield Osborn sent Barnum Brown (a graduate student at the University of Kansas) and H. Menke to open up the famous Jurassic Morrison Quarries near Como Bluff, Wyoming. It was hard work, involving the removal of tons of rock to expose large dinosaur bones, which at times ran deep underground. The bones had to be jacketed, packed and transported to the rail station at Aurora, Wyoming before being carried by train back to New York. Once they arrived at the museum they had to be prepared, at a painstakingly slow pace, and mounted for the exhibit planned for the fourth floor of the museum. Barnum Brown was able to do it better they anyone else, and Osborn enjoyed his frequent visits to the quarries. During the 1898 field season the team discovered a large accumulation of dinosaur bones, which they opened up, calling it “Bone Cabin Quarry” for a small cabin at the site, which a shepherd had built, unwittingly, of dinosaur bones. This new quarry gave the crew an immense amount of work. Others from the museum joined the field crew including Walter Granger, William Matthew, Peter Kaisen, Jacob Wortman, and Al Thomson. After the season ended in July, Barnum Brown accompanied William Matthew and other members of the crew to Nebraska, Kansas and Colorado to do surface collecting for fossil Miocene mammals.

After graduating college in 1898, Barnum Brown was hired by the American Museum of Natural History. His first expedition was to South America, for two years of fossil collecting and anthropological research. He left on December 7, 1898 and returned on June 18, 1900.

The Museum had changed while Barnum Brown was away. The dinosaurs Barnum had collected for the museum had caused a stir with Andrew Carnegie, who wanted dinosaurs for his fledgling museum in Pittsburgh. Andrew Carnegie had lured Dr. Jacob Wortman away from the American Museum, giving him a curatorship. Jacob was a good choice; he had work for eleven years for Edward Drinker Cope, and nine years at the American Museum. He had grown up out west, the son of a 49’er. Carnegie’s Museum was quickly joined by John Bell Hatcher, who had collected dinosaurs for O.C. Marsh at Yale University for many years. Osborn had cause to worry, none of the dinosaurs collected in 1897 or 1898 had been mounted yet, and he did not want Carnegie’s collection to out shine the American Museum.

Osborn immediately sent Barnum west to Wyoming, but this time to find a Triceratops skull from the late Cretaceous, while work stilled continued at Bone Cabin Quarry in the Jurassic Morrison Formation. Barnum arrived at Edgemont, South Dakota, in early July. He hired an assistant H. M. Smith, and a cook named Armstrong. They traveled up the Cheyenne River toward the junction with Alkali Creek, which they followed for 15 miles. The crew of three men camped there for just four days, only finding a fragmentary Triceratops. The crew traveled on, finding a source of water at the head of Seven Mile Creek. Here they camped for the rest of the summer. They did not find much, fossil leaf impressions, a turtle, Triceratops pubis, and a carnivorous dinosaur (Field # 12). The carnivorous dinosaur was found on a small tributary of the Seven Mile Creek, 2 and half miles north of the Cheyenne River,

Barnum Brown wrote the following description of Field # 12:

“The bones of this specimen were disassociated and scattered necessitating the removal of a bank of clay forty feet along face of exposure and back into hills a distance of fourteen feet. In many respects this interesting specimen resembles Ceratosaurs of the Jurassic formation. It consists of lower jaws, having large foramen characteristics of Ceratosaurus, serrated teeth of uneven height joined by cartilage, not anchylosed. Concavo-concave and plano-concave vertebrae of lumbar-dorsal region are deeply excavated on sides and bottom rising to plane surface in region of canal; extremely hollow and as in Morosaurus not having spines and transverse processes united to centra. Sacral vertebrae 3?, postsacral vertebrae of which seven were embedded in stone matrix show plano-plano surfaces. Transverse processes united to centra. Nature of cervical vertebrae not determined. Ribs large, not greatly curved in dorsal region, tapering gradually to those of cervical region. But few chevrons were found, those of extreme length in proportion to size of vertebrae. Numerous plates varying from a half inch to six inches across always found closely associated with ribs formed the dermal armature. On some of these plates there are crossed markings as in Nodosaurus, but it does not appear on all. Numbers of other bones impossible to determine in their matrix complete the specimen. Among the bones were the teeth of Hadrosaurus, Palaeoniscus, the most numerous a species undetermined, scales of fish and small bones, evidence of the animal’s last meal.”

Barnum’s comparison of this specimen to the primitive Late Jurassic genus Ceratosaurus, was based upon the work of O.C. Marsh, who had described and figured several specimens from Canyon City, Colorado.

The crate containing field # 12 was shipped to the museum. The lower jaw was given to E.S. Christman to illustrate in detail for a planned publication authored by Henry Osborn. (see illustration)

In 1901, Barnum took a break from field work, spending just a few weeks with William Matthew, collecting Miocene mammals in Colorado. The dinosaur hunting expedition of 1901 was turned over to Dr. G. R. Wieland, a recent graduate from Yale University, who had collected with O.C. Marsh. Wieland’s expedition proved disappointing, a hind-limb, pelvis and caudal vertebrae of a sauropod and several carnivorous teeth were all that were found.

While hunting deer along the Missouri River in Montana, Dr. William T. Hornaday, then the director of the New York Zoological Park (Bronx Zoo), discovered the horn of a Triceratops. He brought it back with him to New York and had Barnum Brown identify it. Dr. Hornaday was an expert on the Great Plains having dedicated himself to the preservation of the American Bison for the last 20 years. Hornaday was good friends with a number of the land owners in Montana, As the president of the American Bison Society he had convinced the federal government to establish the “National Bison Range,” securing various ranges in Montana for buffalo habitat. Hornaday’s good friend Mr. A. Huffman, had photographed the area where Hornaday had made his discovery 130 miles north of Miles City, Montana. Barnum after examining Huffman’s photographs, was eager to explore this wilderness of Montana.

Barnum arrived in early June, staying at the American Hotel in Forsyth, Montana. He met up with Hornaday’s friends who gave him much needed information about the area. At the National Bank in Miles City fossil bones were on display in the lobby. Barnum heard about another dinosaur discovery five miles away. It proved to be a Claosaurus or more likely Edmontosaurus (Duckbilled Dinosaur), which had been destroyed by souvenir hunters. The skull was sold to the Smithsonian in 1898. Hornaday had written enthusiastically about another dinosaur discovered west of town, which Barnum investigated. The dinosaur turned out to be a mosasaur (Aquatic Reptile), in the marine Fort Pierre Shale. Barnum wrote to Osborn “I was greatly disappointed as you can well believe for I had expected this to be a good specimen from the description of it.” Osborn wrote back to Barnum, “It is certainly remarkable that we should have hit right off upon one of the localities I especially desired to find, namely, the site of the skull [of Claosaurus] in the Smithsonian Institution, which is in beautiful preservation and which I have always admired very much. Judging from your report, you are in what Marsh used to call the “Holy ground”; and there is every reason to think that by careful inquiry among the natives by making friend wherever you can, and by energetic prospecting you may find something of real value. Keep me well informed of your progress.” Barnum started traveling south, along the Powder River, but without much luck. It rained for seven days, and he managed to find a badly crushed Triceratops skull, and a few bits of a turtle carapace. The high shipping cost of these specimens back to New York, later angered Osborn. He thought these specimens were too poor to even bother collecting, much less shipping across the continent.

When Barnum returned to Miles City on his horse, he was met by Richard Swann Lull. Lull had just taken leave of his position as assistant professor at Amherst, Massachusetts to work for the American Museum for a year, while he finished his schooling at Columbia University. He had spent the summer of 1899 working at Bone Cabin Quarry when Barnum was in South America. It was the first time these two men met.

In his later years, Barnum joked about working with Richard S. Lull in 1902,

“One of my assistants at the excavation was Prof. Richard Sawnn Lull of [later hired by] Yale who was a pompous man, and so deaf he could not hear his own footsteps. One day while prospecting he made such a clatter coming down a hill that a big buck deer bounded out from the rocks with great leaps as tho he was on springs. We measure his tracks which were 24 feet apart in each jump. Pro. Lull wanted to take back a souvenir to his wife, and went to Meany’s saddery to buy a belt. “What size?” said Meany. “About 40” said Lull. “Is she a large woman?” said Meany, “No, she’s very small” said Prof. Lull, “I think I ought to know my wife’s size for I have lived with her for 30 years. So Mrs. Lull received a belt size 40 which, as Meany said, would do for a belly-band for a horse.”

Richard Lull signed on an eager student named Phillip Brooks, who arrived a few weeks later on July, 16th, and they headed north into the great badlands that lay between the Yellowstone and Missouri Rivers. They traveled 130 miles on horseback, living on pronghorn antelope that they shot for food. Most of the area was covered by grassland. When the small tributaries, that they were following north, opened into a rugged series of canyons, they discovered the great exposures of Cretaceous rocks photographed by A. Huffman. The crew camped at old Max Sieber’s ranch, at the head of the Hell Creek. Today the land is part of the Charles M. Russell National Wildlife Refuge. The first morning at the camp, July 14th, they made two discoveries. First was a Triceratops located in a clay butte, near Red Butte, southeast of their camp. The skeleton contained a lower jaw, humerus, ulna, radius cervical vertebrae and some fragmentary ribs with several undetermined bones running in the bank. All were crushed more of less and covered with a concretionary matrix. The second discovery was Torosaurus consisting of two femurs with two large vertebrae in a hard sandstone. Barnum knew that with a small crew of three that they would not be able to excavate as much as he would like. He wrote to William Matthew, who was working near Bozeman, Montana looking for early Oligocene fossil horses. Barnum beg him to bring his crew north, however Matthew joined the joint American Museum and United States Geological Survey crew collecting fossil mammals in the Bridger Basin of the Southern Wyoming that year. Barnum’s next discovery was a beautiful skull of Triceratops, including the upper and lower dentition, 120 feet above the Fort Pierre shale. Nearly six feet long, the skull also preserved the base of the horns, base of skull and rostrum. A tibia, humerus, radius and part of the foot were also found. The crew of three were now working at three quarries, the first quarry (Quarry No. 1) the crew begin to uncover bones of a large carnivorous dinosaur, in addition to the Triceratops bones already uncovered. But it was tough work with such a small crew.

While working at this quarry, Barnum Brown came down with a bad case of gout, such that he could barely ride his horse and needed help each night to get into his bed. It was extremely painful for him to work in the quarry.

Barnum wrote to Osborn “the bones are separated by two or three feet of soft sand usually and each bone is surrounded by the hardest blue sandstone I ever tried to work in the form of concretions. There is no question but what this is the find of the season so far for scientific importance. From the pubic [bone] one would think it a Jurassic Dinosaur. It is necessary to shoot [into] the bank from now on and as it is not accessible to horses. Work goes slow. I sent the pubic [bone] and femur in last load in one block which made nearly all the team could pull. Cook just returned and reports safe arrival at Miles [City].” The transportation of the blocks of rock 130 miles to Miles City, Montana was no easily venture. Once in Miles City, Osborn arranged for an empty freight train car to be sent west. Richard Lull and Phillip Brooks headed back east, leaving Barnum in Miles City to explore on his own, and wait for the empty freight car. It was late September and winter was fast approaching. In his heart, Barnum knew that there more to find, so he rode out of town, toward Jordan, Montana. There he collected several Cretaceous Champosaurs (Primitive Crocodiles). In early October, Barnum left all the boxes of fossils collected during the summer in a wool house. Twenty one boxes, weighting over 7,950lbs. The boxes were left in charge of M.G. Maples, a lumber merchant who had visited the American Museum, and was happy to insure the boxes made it on the train. Barnum was instructed by Osborn to check out a Jurassic locality in South Dakota before it got much later in the year.

For the next two years, Barnum Brown was too busy to return to Quarry No 1. The new carnivorous dinosaur from the quarry was slowly being prepared at the museum by Richard Lull. In the meantime, Barnum Brown collected aquatic reptiles in the Fort Pierre Shales in South Dakota, and did a quick survey of the Power River area of Wyoming.

In 1904, Marion Brown, Barnum’s first wife traveled with him and Leroy Perkins. Marion detailed the journey in her diary. They traveled 120 miles from Billings, Montana following the Yellowstone River, toward the Musselshell River, examining the Judith River beds. A Trachodon partial skeleton was excavated, but left covered for a later season.

In 1905, Barnum desperately wanted to return to the Hell Creek. The bones collected from Quarry No. 1, which Osborn now had informally identified as Deinodon (a dinosaur previously only known by fragmentary teeth). As preparation continued the fossil was proving an interesting discovery, and half of the skeleton was still in the rock. Richard Lull had managed to uncover the following bones at the museum: pubes, ischium, angular, distal end of femur, metatarsal, five vertebrae, a postorbital bone, and a mysterious humerus, radius which seemed too small to belong to the specimen.

On the onset of the summer of 1905, the crew left from Fort Benton, heading east along the Missouri River toward Jordan, Montana. It was again a small crew of three people, Barnum Brown, Leroy R. Parkin from South Dakota and a cook. In Billings, Barnum bought a team of two horses. The horses were large and fit from hauling heavy loads of gravel for construction of the new court house. The horses were named Dick and Blue. Dick was a large male with a mange of white hair around his neck. Despite being tied up each night, Dick would always escape and steal a meal of oats from the back of the wagon. Barnum had to keep the sacks of oats in his tent at night. In the mornings Dick would stick his head in the stovepipe hole of the tent, and whinny for a meal of oats.

Heavily rains slowed their progress and in early June disaster struck. A new motorcycle raced by the wagon scaring the team of two horses. The picket pin, which held them to the wagon, broke loose. Blue was badly injured when he ran into a barb wire fence. Barnum had to sew the gash in Blue’s shoulder with a curved needle and rode Dick all the way back to Billings to get another horse. Blue recovered from his injuries and followed along the wagon, but the ordeal cost the crew a month of time.

On arrival, the crew discovered that William Utterback from the Carnegie Museum had been hunting for fossils along the Hell Creek, just a few weeks before they arrived. In addition, word reached New York that the Carnegie Museum was finishing the last of its preparation of an articulated skull, and partial skeleton of a new carnivorous dinosaur from the Cretaceous (CMNH 1400). Olof Peterson had collected the specimen in Wyoming during a brief expedition in 1902. The specimen contained the skull, both lower jaws, two dorsal, seven caudal vertebrae, ribs, chevrons, pubis, ilium, femur and associated fragmentary bones.

Henry Osborn was a little worried, he had planned on writing the definitive paper on carnivorous dinosaurs, and now it looked as if the Carnegie Museum was going to beat him to it. The America Museum did not have a single skull of any Cretaceous carnivorous dinosaur, and the best specimen was still mostly unexcavated.

Barnum and Leroy set up camp at the Hell Creek site on June, 24. They were both relieved to see that Quarry No. 1 was not disturbed since it was last visited by Barnum three years ago. Leroy was given the hard task of digging up the rest of the skeleton, referred to in Barnum’s letters as the “Old Deinodon Skeleton.” The quarry sat precariously on a cliff face, 75 feet above the Hell Creek. Horses were used to plowed the top of the quarry open, but at a depth of 9 feet hard sandstone was hit. Barnum wrote back to A. Hermann, the chief preparator to send some chisels and awls tempered for the hardest of rock. Word of the discovery of more bones reach Henry Osborn on July, 6 who wrote to Barnum “I was very glad to receive your letter from Jordan, Montana and to learn of your success in finding more of the “Deinodon” bones. I think it is well worth while making a good deep cut and hunting for more of that animal, every portion of which will be valuable.”

In early July, Leroy struck the other femur, and another small humerus. Barnum wrote to Osborn to caution him from publishing anything about the specimen until he could be certain that the skull bones, small humeri and other bones belonged to the same animal.

At this point the quarry extended for 30 by 15 feet, and was 11 feet deep. A skull bone was discovered in a hard concretion descending down into the hard sandstone. This skull bone later turned out to be the ilium (part of the pelvis).

It was a great race to see if the skull was still in the rock and learn as much about this new creature before Olof Peterson could publish his paper on the skull at the Carnegie Museum.

It was now time to use drastic measures. Dynamite was used to blast the out the remaining nine feet rock and Barnum hired two addition men to help in the excavation.

Back in New York, Henry Osborn set to writing his paper on Cretaceous carnivorous dinosaurs. E.S. Christman had finished his illustration of the jaw (Field # 12), from Wyoming. Osborn gave this specimen the name “Dynamosaurus imperiosus.” The new specimen, currently being excavated by Barnum in Montana, Osborn gave a more familiar name – “Tyrannosaurus rex.”

Osborn doubted that the humeri belonged to the same specimen. On the hastily drawn illustration Osborn’s caption reads: “The association of the small forearm is probably incorrect.” The skeleton figured is a composite of both specimens. (Field # 12; AMNH 5866 and the new skeleton from Quarry No. 1; AMNH 973).

On July, 15th 1905, Barnum wrote to Osborn, “Am now at work on the second large cut in the Deinodon quarry, which is 100 feet long, 20 feet deep, 15 feet wide; hard sandstone, which has to be blasted before it can be plowed. This is a heavy piece of work, but Deinodon bones are so rare that it is worth the work. Since writing to you I have made the important discovery that the large limb bone thought to be a femur is a humerus and only slightly shorter than the femur judging from the femur from Wyoming. The large bone, which I thought a skull bone at first turns out to be an ilium when taken out. This will change our idea entirely of the structure of Deinodon.” Osborn wrote back “Your letter is interesting. I have just described the big dinosaur under the name Tyran[n]osaurus rex. I hardly believed it possible that the humerus you have found belongs to this animal. It will upset absolutely all that is known of the osteology of these carnivorous animals. Of course it will give Tyran[n]osaurus a very clear and marked separation, but considering the many points of close resemblance between this animal and Allosaurus I hardly think it possible that it has a long fore arm. If you strike another animal in this quarry you will of course have a somewhat less clear path ahead of you, so I hope you will prove to be right and the bone you have found will prove to belong to Tyran[n]osaurus, paradoxical as it may appear. I have been thinking a great deal about your work.”

Despite having named the new carnivorous dinosaur specimens, Osborn was still greatly worried that the Carnegie Museum was out pacing the America Museum in its collection of dinosaurs, particularly from the Cretaceous period. J. B. Hatcher from the Carnegie Museum had already published a monograph on the ceratopsian [horned] dinosaurs, which are only found in rocks of the Cretaceous period.

Osborn gave the following advice to Barnum; “It simply wets my desire to get a collection of these animals for our Museum. I think this can only be done by prospecting, and that it is poor policy for us to do any more digging than is absolutely necessary in order to see that specimens are well taken out; so I say once more, prospect, prospect, prospect! Granger was digging instead of prospecting when he let Wortman [working for the Carnegie Museum] slip in and find that big Diplodocus. As regards the Claosaurus skeleton you must keep your eye on that, and see that it does not slip out of our hands to some other parties, that is, if it is really valuable.”

The crew, rather than taking Osborn’s advice to prospect, kept working hard at the quarry. Barnum wrote to Osborn in early August “The work on Tyran[n]osaurus is being pushed rapidly. I have a force of three men besides myself and it is imperative that I supervise this work till completed; that is till this 20 feet cut is taken out and then if the bones continue into the bank as I think they will I shall let a contract to have the upper 20 feet of sandstone removed this winter for that will be cheaper than keeping an expensive outfit on the ground….. I trust this meets your approval and I should like your opinion immediately, It means a great deal of expense, but this is the rarest animal in the Laramie and I have never seen another fragment of it anywhere. Up to date, I have taken out femur, humerus, scapula?, metapodial, several ribs, skull bones, both lower jaws, ilium, and some bones not identified on account of [the] matrix. There is no question regarding the association of the humerus for the only other animal in this quarry is the little carnivore of which we have the humerus and end of the femur. This specimen is entirely distinct from the carnivore secured in Wyoming [Field # 12] and will prove a different genus as I remember the shape of teeth and femur? in that specimen. Moreover, I have not found any plates with this animal and the other is a plated dinosaur. I am confident it is a mistake to combine the remains of the two.”

By the end of August 1905, the bones contained in Quarry No. 1, were fully removed, boxed and transported back to Miles City, Montana.

As the winter months set in, Paul Miller and Peter Kaisen begin to prepare the specimen collected from Quarry No. 1, AMNH 973. They also starting working on cleaning up Field # 12, AMNH 5866, from Wyoming. The extremely fragile bones of Field # 12 were loosely held in a soft matrix of clay, making preparation difficult. Many unassociated bones were found mix in with the creature now called Dynamosaurus, including the frill of a Triceratops, and a jaw of a hadrosaur. The dermal plates caused some confusion, for no dermal armor was found with AMNH 973, from Quarry No.1, and that specimen was much more complete, yet the bones of both specimens appeared to be nearly identical. Osborn, in his follow up publication of 1906, recognized both specimens under one species name; Tyrannosaurus rex.

Barnum continued to work in the Hell Creek beds for the next several seasons, discovering a number of Triceratops and hadrosaurs. In 1908, Barnum was accompanied by Peter Kaisen, and C.H. Lambert as the cook and teamster. On July 1st, Barnum opened up a quarry, which contained various dinosaur bones. On the way back to camp one day 1 mile east of the Big Dry Creek (30 miles south of the Missouri River), Barnum came across four weathered caudal (tail) vertebrae that were running into the side of a sandstone hill. Following the bones into the sandstone, Barnum uncovered a series of 15 articulating vertebrae. It appeared that the vertebrae bones belonged to a third skeleton of Tyrannosaurus rex. With the use of a plow and lots of dynamite, the vertebrae bones were followed into the rock, reviling a pelvis, then articulating ribs, and finally a complete skull.

During this time the crew stayed near the Twitchel and Willis ranches, land now flooded from the Fort Peck Dam, on the Missouri River.

Barnum Brown in 1960 recounted several antidotes about staying on the Twitchel and Willis ranches:

“Once our camp was located a few miles from the John Willis ranch where we want for mail and supplies. One day while riding to the ranch, I was on a high plateau where I saw horse tracks headed for the ranch. I followed them, but to my consternation the horses had plunged over a cliff 75 feet high and almost vertical. It took a half hour searching to find a safe trail off the plateau. When I reached the ranch I told the family what an extraordinary occurrence I had seen where a bunch of horses had gone over a cliff. “Yes”, said Bessie Willis, the daughter, “I drove them over and went over after them.” Her father only laughed, for Bessie was dauntless, and this was to her no unusual exploit. The horses had broken back many ties refusing to leave the plateau, and when Bessie saw an opportunity to force them over the cliff in a bunch, she was too mad to hesitate or consider for she was bound to get that particular bunch corraled. Bessie was a noted rodeo-rider, and fearless…… I’d ride to the Willis ranch for mail, if a storm was brewing I would see many cattle running down the hills, kicking up their heels – a sure sign of a coming storm. One day, when I stayed for lunch with the family, “Billious Bill”, a CK (brand for Conrad Kore) cowboy rode up and said, “John, I was driving a bunch of cattle along your north fence, and they tore down a couple of yards of it.” “All right, Bill, I’m glad you told me,” said John Willis, and to his son he said, “Claud, if Bill said a couple of yards he meant a quarter of a mile at least, so after lunch hitch up the team, take wire and posts, and repair the fence.” Bill was a comical fellow with a protruding teeth, and when talking he always held his hand over his mouth to hide this defect…. [In 1904], my first wife, Marion, was with me. She had never been west before this trip, and I wanted her to taste fresh meat from the range. Riding over to the 79 Roundup Camp nearby, I explained the circumstances to the cook, and wanted to buy some meat. “Hell, no, you can’t buy this meat”, said the cook, as he tied a hind quarter of a yearling steer onto my saddle – meat that is rare, if unattainable in New York City. Fair for the most part; just and generous, were these early pioneers of the west. If there was sickness in your family, someone came from miles away to help. If you rode up to a house and no one was at home, you usually found a note tacked on the door. “Help yourself to what you need, but leave the dishes clean.” In those days it was not all work on the ranches, or in fossil camps. We had a dance once at the Twitchel ranch – a three roomed log house. The music was a phonograph, and Bessie Willis rode all over the country collecting records. She was the only unmarried female in the region. The babies were ricked along the floor on bed rolls, and as the women played out they took to beds, as the men retired to the haymow of the barn. This dance was a gala 4th of July [1908] affair, starting the afternoon of Friday, continuing all that night; and a few women lasted till Saturday morning, or recovered after a sleep, to keep it going. Bessie Willis went all the way through, for it was her party.”

After the 1908 season, the American Museum of Natural History, had two nearly complete skeletons of Tyrannosaurus rex (AMNH 973, from Quarry No. 1 and now this new skeleton, AMNH 5027). By 1912, the Museum had discovered eight specimens of Tyrannosaurus rex from Montana and Wyoming. Using the new complete skull AMNH 5027, Henry Osborn described the cranial anatomy of Tyrannosaurus, making comparisons with the skull of Allosaurus. The publication featured not only detailed descriptions, illustrations and photographs of the cranial bones of Tyrannosaurus, but also a detailed study of the endocast of the brain from a recently recovered skull (AMNH 5029). (Osborn, 1912)

Work also immediately begin on mounting the two nearly complete skeletons of Tyrannosaurus rex (AMNH 973, and AMNH 5027). The staff artist, E.S. Christman was given the task of preparing a scale model of every bone in the skeleton mounted with flexible joints to enable to study of various poses for the skeletons. Raymond L. Ditmars, the Curator for Reptiles at the Bronx Zoo, came up with the winning pose.

Barnum would describe the pose in 1915 “It is early morning along the shore of a Cretaceous lake [sixty five] million years ago. A herbivorous dinosaur Trachodon venturing from the water for a breakfast of succulent vegetation has been caught and partly devoured by a giant flesh eating Tyrannosaurus. As this monster crouches over the carcass, busy dismembering it, another Tyrannosaurus is attracted to the scene. Approaching, it rises nearly to its full height to grapple the more fortunate hunter and dispute the prey. The crouching figure reluctantly stops eating and accepts the challenge, partly rising to spring on its adversary. The psychological moment of tense inertia before the combat was chosen to best show positions of the limbs and bodies, as well as to picture an incident in the life history of these giant reptiles.” (Brown, 1915).

Work began on the more difficult rearing posed of the Tyrannosaurus, using bones from AMNH 5027. Since this specimen did not preserve limbs, casts of the femurs, tibia, fibula, and pedial bones were made from the type specimen from Quarry No. 1. Since only the humerus was known of the forearm, casts were made based on the forearm of Allosaurus. As work proceed for the mount of Tyrannosaurus rex, it became apparent that the planned grouping of two fighting Tyrannosaurus rex skeletons would not fit in the current Cretaceous Dinosaur Hall. Over the past several years the museum had been working hard to raise 1 million dollars to build an addition wing and entrance on the Central Park side of the museum. In the autumn of 1915, seven years after its discovery, the museum finished its mount of AMNH 5027, the first Tyrannosaurus rex skeleton to ever be mounted in a life like pose. The skeleton was 18 and half feet high and 47 feet in length. Its skeleton posed as it reared up from it’s yet to be constructed adversary. To help raise the funds for the new wing of the museum, the mounted skeleton of AMNH 5027 was placed as the central attraction of the Cretaceous Dinosaur Hall, without the other planned skeleton. Charles Knight was commissioned to paint a mural to stand before the mounted skeleton.

After 1912 Barnum Brown started to intensely collect dinosaurs from the Cretaceous beds in Alberta, Canada, along the Red Deer River. With no room to mount the second “crouching” skeleton of Tyrannosaurus rex, the bones of AMNH 973 remained in the collection, until 1941.

In the fall of 1940, Barnum Brown was a much older man in his sixties, Henry Osborn his previous boss died in 1930. Barnum Brown was traveling across the country giving lectures on Dinosaurs, yet the attention of his audiences were distracted by the endless bombing of London by Nazis Germany. By October 1940 over 50 million pounds of bombs had been dropped on the city of London. Buckingham Palace, Westminster Abbey and the British Museum were under siege from the air.

In late December 1940, Barnum Brown met with James Leroy Kay of the Carnegie Museum. James L. Kay grew up in Vernal Utah, and had worked on the Carnegie Museum’s excavations at Dinosaur National Monument. He spent his summers collecting dinosaurs in Montana for Carnegie’s Museum. Despite a promising start, the Carnegie Museum still had no Tyrannosaurus rex skeleton. Kay was interested in acquiring a more complete skeleton of Tyrannosaurus rex any way he could. The American Museum had never finish mounting the skeleton from Quarry No. 1 as planned in 1915. The three best skeletons of Tyrannosaurus rex were all housed in New York City; the Carnegie Museum only had (CMNH 1400), in which the maxilla bone was on display. As the war raged in Europe the Barnum Brown agreed to sell AMNH 973, the holotype of Tyrannosaurus rex to the Carnegie Museum with the proceeds to establish an endowment for research at the American Museum. A couple years before his death, Barnum Brown wrote: “we were afraid the Germans might bomb the American Museum in New York as a war measure, and we hoped that at least one specimen would be preserved.”

 In 2003, the Carnegie Museum renovated the type specimen (AMNH 973) of Tyrannosaurus rex, removing many of the old metal mounts and plaster used to hold together the specimen. The skull bones are now restored in more correct position based on more complete skulls, and now two skeletons pose in battle at the museum.

However, in 2011 it was discovered that several bones of AMNH 973 remained at the American Museum, these bones were transferred to the Carnegie Museum so they could be reunited with the rest of the specimen (link).

The mounted skeleton AMNH 5027 at the American Museum was remounted in the late 1990s, to a more correct pose, with the tail fully off the ground and head pointed straight ahead, as if it was stalking prey.

References:

Brown, B. 1915. Tyrannosaurus, a Cretaceous carnivorous dinosaur, the largest flesh-eater that ever lived. Scientific American. v.63,15:322-323.

Osborn, H.F. 1905. “Tyrannosaurus and other Cretaceous carnivorous dinosaurs”. Bulletin of the American Museum of Natural History 21: 259–265. 

Osborn, H.F. 1906. Tyrannosaurus, Upper Cretaceous carnivorous dinosaur (second communication). Bulletin of the American Museum of Natural History 22: 281-296.

Osborn, H.F. 1913. “Tyrannosaurus: restoration and model of the skeleton”. Bulletin of the American Museum of Natural History 32: 91–92.