Summer 2008
Mural created by Walters & Kissinger in collaboration with Carnegie Museum of Natural History.
Clash of the "Tyrant Lizards"
By Reid R. Frazier

The climactic finale of Dinosaurs in Their Time showcases the museum’s original T. rex in a bitter brawl with a fierce new nemesis, and re-creates the lush world of the final period of the dinosaurs.

The massive thighbones. Those antenna-like forelimbs, improbably puny on such an enormous creature. Those six-inch teeth. The jaw-dropping power of a 40-foot-long, five-ton body.

It will all be instantly recognizable. But when unveiled again this June, the first skeleton of the world’s most famous dinosaur will still look plenty different.  

After a three-year makeover and spinal adjustment, Tyrannosaurus rex is back at Carnegie Museum of Natural History, culminating the museum’s groundbreaking, $36 million exhibit, Dinosaurs in Their Time. “Phase Two” picks up where the first part left off, showing North American dinosaurs from late in the Cretaceous Period, circa 66-68 million years ago, in the world they would have inhabited shortly before the mass extinction that ended their reign.

By now, more than 100,000 visitors have wandered through the opening phase  of the exhibit, a chronological journey through the Age of Dinosaurs that uses the museum’s extensive fossil collection and some impressive new additions to re-create the environments in which the dinosaurs lived. The path begins with the small, earliest dinosaurs that emerged during the Triassic Period, some 215-230 million years ago. From there, it snakes into the towering, cavernous Jurassic Atrium, which houses gargantuan sauropods that lived roughly 150 million years ago, and features old friends like Dippy and new treasures like the recently named Ajax—the only baby Apatosaurus on display in the world.

After the museum puts the finishing touches on the Late Cretaceous section of the exhibit, visitors will step into a fierce scene from the very end of the Age of Dinosaurs—a pair of Tyrannosaurus rex squaring off over the carcass of a fallen Edmontosaurus, a duck-billed, plant-eating dinosaur that was common prey for these giant carnivores. The pair will be surrounded by smaller dinosaurs, plants, and other animals they lived alongside in an environment that existed in western North America about 68-66 million years ago. This ancient ecosystem is preserved in what is now the Hell Creek Formation, a swath of rocks exposed in parts of Montana, Wyoming, and the Dakotas.

“It’s the grand finale of non-avian dinosaurs in North America,” says Matt Lamanna, assistant curator of vertebrate paleontology and the lead scientist behind Dinosaurs in Their Time. And he’s not just talking figuratively. “It’s quite likely Tyrannosaurus rex was still around when the big asteroid hit about 66 million years ago and wiped out all dinosaurs except some birds.”

Obviously excited about what the museum’s creating, Lamanna explains that the “tyrant lizard king” was the unquestioned ruler of the American West during the final few million years of the Age of Dinosaurs. It was one of the largest terrestrial carnivores to ever walk the Earth, weighing as much as a bull elephant yet supported by only two powerful legs. “Standing next to them, the way the legs are built, you get this feeling of colossal power,” says Lamanna. “It would have been terrifying to see in the flesh.”


To create the climactic fight scene, the museum remounted its famous T. rex skeleton, which has been part of its collection since the 1940s and is the holotype of the species—meaning, it is the definitive, name-bearing specimen, the one to which all others must be compared to determine whether or not they really belong to the species T. rex. Its equally gigantic opponent is a newly acquired cast of the Tyrannosaurus skeleton, nicknamed “Peck’s Rex” after the location where the original specimen was found, near Fort Peck, Montana.

The two tyrants face one another—frozen mid-roar, as it were—battling over dinner. And each specimen is dynamically posed, so visitors should brace themselves for a close-up of those six-inch-long teeth. In keeping with current scientific understanding, the T. rex skeletons are positioned such that their backs are nearly horizontal—their powerful jaws now just a few feet above eye level. Their tails are held parallel to the ground (picture a roadrunner with a head about half the size of a Volkswagen Beetle).

“Most modern reptiles drag their tails when they walk. So when dinosaurs were first discovered, the posture of T. rex was thought to have been Godzilla-like or kangaroo-like,” Lamanna says. To get a T. rex into that tail-dragging position, however, scientists had to stand it up with its torso more or less perpendicular to the ground. The problem was, Lamanna explains, paleontologists began to realize that fossilized dinosaur trackways, of which there are now thousands from all around the world, almost never included evidence of tail dragging. Paleontologists also began to suspect that dinosaurs were the direct ancestors of modern-day birds, leading to a revolution in the scientific perception of these animals. No longer were dinosaurs considered awkward, sluggish, and lizard-like; instead, they were recast as remarkably avian creatures with stances and gaits to match.

The fossils that surround the two T. rex in Dinosaurs in Their Time also come from the Hell Creek Formation. The sandstones and siltstones  of these strata were laid down on a steamy, semi-tropical floodplain on the western edge of an inland sea that extended nearly from the Arctic Ocean to the Gulf of Mexico, where T. rex and other dinosaurs thrived, explains Lowell Dingus, a research associate at the American Museum of Natural History. Dingus is writing a biography  of Barnum Brown, the renowned fossil hunter who discovered Carnegie Museum of Natural History’s holotype T. rex at Hell Creek, Montana, in 1902.

“The Hell Creek Formation gives us our last glimpse of the flora and fauna of what is now  North America, just before the Age of Dinosaurs comes to an end,” Dingus says. “Think of it as a few frames in a movie right before all the large dinosaurs went extinct.”

This ‘last glimpse’ includes several horned dinosaurs, most notably Triceratops, the most
ubiquitous dinosaur of the Hell Creek Formation. Dinosaurs in Their Time will showcase a mounted skeleton of this three-horned herbivore capped by an original fossil skull discovered by museum collector William H. Utterback more than a century ago. Visitors will learn how Triceratops descended from other horned dinosaurs that migrated to North America from Asia at least 100 million years ago.

Triceratops skull
This real Triceratops skull was found by a Carnegie Museum of Natural History collector more than a century ago. Here, Dan Pickering of the museum’s Paleolab readies it to be remounted.

Other specimens on display include an Edmontosaurus (the what’s-for-dinner specimen that has the two T. rex all hot and bothered); a skeletal mount of the “thick-headed lizard” Pachycephalosaurus—so named for its six-inch-thick skull; a still-unnamed, ostrich-like oviraptorosaur, which Lamanna himself is currently studying; and a gigantic flying pterosaur known as Quetzalcoatlus, the 35-foot wingspan of which places it among the largest flying creatures of all time.

Several of these skeletons (the T. rex holotype, Edmontosaurus, and Triceratops) include real fossils, while others are casts obtained from other institutions. In the case of the skull of the holotype T. rex, which contains only eight of the original 65 or so cranial bones, the museum combined casts of these eight bones, including those in front of the eyes and upper and lower jaw elements, with casts of other T. rex skull bones from the Museum of the Rockies in Bozeman, Montana, to build one complete skull. The eagle-eyed visitor may find the real fossils in the holotype mount by looking at its back, shoulder, hip, and leg bones.

Visitors will come face-to-face with other Hell Creek critters, too, including real fossils of a salamander, a lizard, a crocodile, and several mammals. Fossil Frontiers, a changing exhibit, will highlight the latest discoveries of the museum’s world-renowned paleontologists and evolutionary biologists.

Like the great Jurassic Atrium, the walls of the new Cretaceous Hall will feature a vivid mural that depicts the lush landscape inhabited by these creatures, along with two Triceratops, a herd of four Edmontosaurus, and a Pachycephalosaurus fleeing the dueling T. rex pair at the center of the scene. “The other dinosaurs in the exhibit are meant to look edgy, nervous,” Lamanna says. “They know there are two multi-ton carnivores about to tear each other apart over this Edmontosaurus.”   

Onlookers combing the Hell Creek mural for hidden surprises will discover something barely visible in earlier phases of the exhibit—flowers. It was only during the final stages of the Cretaceous Period that angiosperms—flowering plants—began to dominate the landscape. The T. rex duo will be surrounded by relatives of today’s magnolias and sycamores, along with ancestors of many other kinds of flowering plants.

“We hope it’ll be really thought-provoking,” notes Lamanna, “walking in this exhibit and seeing dinosaurs side-by-side with magnolia trees and buttercups and palms, things we’re used to seeing in our own landscapes. The modern world had its roots in the Age of Dinosaurs.”
T. rex vs. T. rex is presented by

Pittsburgh's famed T. rex, as depicted here in old Dinosaur Hall, has changed plenty.
Pittsburgh's famed T. rex, as depicted here in old Dinosaur Hall, has changed plenty.


The most important of the specimens to be unveiled in Phase Two of Dinosaurs in Their Time is, of course, the holotype T. rex, discovered in 1902 by Barnum Brown, a young paleontologist with an uncanny “nose” for sniffing out fossils. While scouting for the American Museum of Natural History, Brown got wind of a settler who had found a rich fossil deposit in eastern Montana. It didn’t take Brown long to find the site, and with it, an entirely new species of dinosaur.

Unlike other meat-eating dinosaurs, whose teeth were shaped like steak knives, the creature Brown had discovered had huge teeth shaped like spikes.

“Quarry No. 1 contains (several bones) of a large Carnivorous Dinosaur,” he reported from the field to his boss in New York, American Museum director Henry Fairfield Osborn. “I have never seen anything like it from the Cretaceous.”

Brown had discovered the T. rex holotype, but the skeleton presented scientists with a puzzle: How could something so big have such small forelimbs? Did the seemingly undersized arms belong to the same animal or to a different species?

Scientists think they’ve solved this puzzle, says Matt Lamanna, assistant curator of vertebrate paleontology at Carnegie Museum of Natural History. Over millions of years, as tyrannosaurs evolved larger heads and more powerful jaws, their forelimbs became less and less important for hunting and killing, and diminished in size.

At 40 feet long, the holotype remains one of the largest Tyrannosaurus specimens ever found. It preserves about 40 percent of the creature’s skeleton.

But the New York museum never displayed Brown’s great find, opting instead to mount and display another of his discoveries, a more complete skeleton of T. rex unearthed several years later. At the end of the Great Depression, with a dwindling research budget and fears of attack by German bombers, the American Museum decided to sell the T. rex holotype to Carnegie Museum of Natural History. The price? $7,000. That’s about $100,000 in today’s currency. For the price of a modest house, the museum had purchased arguably the most important dinosaur specimen of all time. By 1942, the holotype was on display in Pittsburgh, where it remained—upright—until 2005.

Lamanna hopes that, once again unveiled to the public, the near-mystical power of
T. rex will stoke some of the essential questions that dinosaurs always seem to provoke.

“There are a lot of parallels to today,” notes Lamanna. “The big dinosaurs seem invincible, but they all died 66 million years ago. You wonder, ‘If it happened to them, can it happen to us?’”
Also in this issue:

Celebrating the Mark that Makes Us Human  ·  Voices From Mars  ·  American Doggedness and the Carnegie International  ·  Hip to Be Square  ·  Special Supplement: Thanks to Our Donors  ·  Director's Note  ·  NewsWorthy  ·  Now Showing  ·  Face Time: Sam Taylor  ·  About Town: Robotic Wonder  ·  Field Trip: Red Hot Find  ·  Science & Nature: Ready, Set, Go! Sports Works 2.0  ·  Artistic License: Kinetic Energy  ·  Another Look: Section of Mollusks