Tyrannosaurus rex and its prey, a fallen Triceratops—a detail from a 1998 mural by artist M.W. Skrepnick. The full mural is displayed in Carnegie Museum of Natural History’s Dinosaur Hall.

By R.J. Gangwere

Carnegie Museum of Natural History is known locally and internationally for its research in biodiversity. Each year, the museum sends scientists into the field to locate and identify all the living species in a particular area, and to examine how living plants and animals relate to each other. Its “Bioblitzes”—24 hours spent in Pittsburgh’s parks, studying all the plants and animals—have turned up 1,200-1,800 species each year for several years. And week-long “BioForays” at the museum’s Powdermill Nature Reserve have studied the ecological relationships among many species. Internationally, the museum’s department of Invertebrate Zoology (insects) is on a five-year mission with Harvard University and the Smithsonian to document threatened native species on the island of Hispaniola—a Caribbean environment where some flora and fauna are on the brink of extinction.

Soon, the museum’s expertise in biodiversity will be showcased for all the world to see in a collection of exhibits called Dinosaurs in Their World, which is driving the museum’s biggest expansion since 1907. In fact, Carnegie Museum of Natural History expects the “world” aspect of its new display—the ecological environments in which dinosaurs lived—to be a tourist attraction for dinosaur lovers everywhere, and one that will draw visitors to Pittsburgh.

“The idea for Dinosaurs in Their World came to us when we reacted to the way the American Museum of Natural History recently restored its dinosaur halls,” says Bill DeWalt, director of Carnegie Museum of Natural History. “They developed their permanent halls around the scientific method of evolutionary descent [or cladistics]—explaining how you differentiate one kind of vertebrate from another. It’s scientific in a way that I think only a very small percentage of the public can get much benefit from.

“ We are trying to do something more appealing to a greater percentage of the public—that is, put dinosaurs into their world and emphasize biological diversity and how that changes through the years, rather than how dinosaurs evolved one from another. Ours is a more ecological approach.”

“ Dinosaurs in Their World is about more than just the animals and plants that make up the ecosystem,” says Curator of Vertebrate Paleontology Chris Beard. “It’s really about the world itself, which was evolving and changing under the feet of the dinosaurs. At the start of that time, modern continents did not exist but were all part of a giant land mass that scientists call ‘Pangaea’ [all earth]. Before we even talk about the plants and animals that made up the biodiversity of the dinosaurs’ worlds, the museum has to talk about those different worlds themselves.”

The subject is hard to grasp. With an expected lifespan of 60 to 80 years, a recorded “civilized” history that dates back only 5,000 years, and humanoid ancestors that evolved a mere three million years ago, the average person has a limited sense of the time involved in evolution. It takes a geologist or a paleontologist to comprehend the nature of life on Earth when the Age of Dinosaurs began some 248 million years ago and ended about 65 million years ago. To help us, geologists have divided that long period of the Mesozoic Era into three different worlds or periods: the Triassic, the Jurassic, and the Cretaceous. Dinosaurs in Their World will represent each of these periods in its exhibits. Those exhibits will start by explaining the climate and geology of the period, and then focus on one particular area where the scientific collections are excellent and the history of fieldwork by the museum provides special expertise.

Then, as now, plants of all types were dominant in terms of sheer biomass, both on land and in the sea. In addition, the myriads of insects, spiders, crustaceans, and similar animals are not fully seen in the fossil record.

The Triassic (248 to 206 million years ago)—42 Million Years of Transition

The Age of the Dinosaurs was held together at the ends by two great
mass extinctions of life forms. The “Permian Extinction” of 248 million years ago set the stage, killing off over 90 percent of living species in the seas and on land. What caused this extinction has long been debated, but there is no argument that the global climate became inhospitable or toxic to life.

Still, some marine and terrestrial species survived, and reptiles began to adapt to the world of the Triassic Period. Early dinosaurs appeared in a landscape much different from today’s. It was a transitional period, extremely hot in the middle of the giant land-mass, with smoking volcanoes and ever-widening oceans beginning to separate the land into continents. For 42 million years, this first world saw the progressive breakup of Pangaea into large pieces, which is the basis for the theory of Plate Tectonics. As the separate continents came to exist, terrestrial species began to differentiate themselves on each of them.

For the Triassic Period, the Dinosaurs in Their World exhibit will focus on Ghost Ranch, New Mexico, where Carnegie Museum of Natural History Paleontologist Dave Berman conducted extensive fieldwork in the 1980s, producing extraordinary collections for the museum. Ghost Ranch is one of the best North American sites of the Triassic Age, and the museum can tell the story of which animals lived there, and what life and the ecosystems of that period were like.

One of the earliest North American dinosaurs from this period, which lived about 220 million years ago, was the fast and agile dinosaur Coelophysis, a predator that probably hunted in packs, with powerful rear legs and razor-sharp teeth. Botanically, plants began to differentiate during the Triassic Period, and fern-like plants and conifers developed.

Curator Zhexi-Luo also points out that the evolutionary line of mammals began in this period. “Anatomically defined mammals appeared about the same time as anatomically defined dinosaurs,” explains Zhexi-Luo, who also serves as interim associate director of research and collections. “There is always this shared history of mammals and dinosaurs.”

Luo’s work in China has yielded some of the earliest mammal fossils, which were very small at the start. One example is Hadrocodium, a large-brained but tiny creature the size of a paperclip, from the Early Jurassic, and another is the 6-inch, one-ounce Sinodelphys, the most primitive ancestor of marsupials (animals with pouches for raising young). He notes that in the fossil collection is a Phytosaurus— “A very interesting animal that put its body and head in the water, and had a volcano-like nostril on the dorsal side of its head. These are common from the late Triassic time, when the dinosaurs originated. And there were lots of crocodiles—and we have a fine fossil of a baby crocodile from the Triassic.”

The Jurassic (206 to 144 million years ago)—High Tide for Dinosaurs

Biodiversity in the long Jurassic Period (about 62 million years) included the development of flowering plants. The familiar gingko tree is one species that survives from this period. In the air, winged lizards (Pterosaurs) began to glide, and true birds with feathers began to evolve from the scales of animals.

To tell the Jurassic story, the museum has excellent fossil collections from Dinosaur National Monument, which Carnegie Paleontologist Earl Douglass
discovered in 1909. That incredibly rich site of dinosaur fossils was declared a national monument in 1915 by President Woodrow Wilson, a friend of Andrew Carnegie’s, and the Carnegie Quarry continued to operate there until 1923. Today the 200,000-acre national monument extends into Colorado.

Many of Carnegie Museum of Natural History’s most dramatic specimens come from this amazing “bone bed,” which yielded 20 mountable skeletons representing 10 different species, including the long-necked, long-tailed, plant-eating sauropods: Apatasaurus, Diplodocus, and Camarasaurus. Stegasaurus, with its high backbone plates, and Allosaurus, the abundant predator and dominant meat-eater of its day, likewise come from Dinosaur National Monument.

The Cretaceous and Extinction (144-65 million years ago)

Tyrannosaurus rex, the classic predator and scavenger, evolved during the Cretaceous Period, as did another popular dinosaur, Torosaurus, a plant-eater with long horns and a giant frill over its eyes.

In the Cretaceous hall of exhibits, the museum will focus on Lance Creek, Wyoming, where its Triceratops specimen originated, and talk about the work of John Bell Hatcher (“Mr. Triceratops”), one of the museum’s most famous curators from the early 20th century. Triceratops was one of the last dinosaurs to live in North America, and its head was one of the biggest of any land mammal, with long horns, hooked snout, and wide, shield-shaped frill.

The coastal deltas were the home of plant-eating Triceratops 67 million years ago in what is now the Great Plains, but then was covered by a shallow sea. On these huge deltas, Triceratops’ home resembled the warm, wet bayou country of our modern Gulf Coast. Grass had not yet evolved, but the new flowering shrubs that Triceratops ate and the trees that shaded it were early cousins of today’s plants. Sequoia, sassafras, and relatives of the fig grew here in lush thickets and groves. Many species of reptiles, mammals, and birds had evolved into familiar forms, and rivers were full of fish: stingrays, perch, gar, and bowfin, along with turtles and frogs whose descendants live today.

In fact, an entire part of the Cretaceous gallery will be devoted to the Cretaceous North American marine seaway, the vast shallow sea that extended across the middle of the North American continent, covering places that we now know as Kansas, South Dakota, and Nebraska. This seaway teamed with marine life, including Mosasaurs (great lizards that returned to the oceans to swim), Icthysaurs (fish-like reptiles that no longer exist, but that looked like sharks and dolphins), and Plesiasaurs (the long-necked reptiles that gave rise to the Loch Ness monster story).

The most famous, if not the largest, of all mass extinctions marks the end of the Cretaceous Period, 65 million years ago. One theory contends that a giant asteroid hit the Earth near the Yucatan Peninsula in Mexico, sending debris into the atmosphere that affected the photosynthesis process globally, ending much plant life and the animals that depended upon it. This was the great extinction in which the dinosaurs died out.

But while many species disappeared, including marine reptiles and flying pterosaurs, there were other groups—such as flowering plants, snails, and clams, amphibians, snakes, lizards, mammals, and crocodilians—that “crossed the boundary” of the great extinction to live on and flourish in more modern times.

Show Me the Fossils

The best proof of what the world of the dinosaurs was like is to be found in the rare fossil evidence that only a few museums possess. All the overwhelming popular attention—the publicity, the games, and the movies—depends on this real fossil evidence, and Carnegie Museum of Natural History, with its 100 years of research and collections, has some of the best evidence to be found anywhere.

Says Carnegie Museum of Natural History Curator Emeritus Mary Dawson, “These are animals that once lived, breathed, walked around, ate, reproduced, and died—what can be more astounding than being in a room with 12 or 13 of such animals that were once alive? Seeing the real thing is important for people who really have an appreciation for life, for the past, and for the future. That you get from originals. You don’t get it from copies. A plaster cast is just an artifact. It is not a fossil.”

Dawson’s associate at the museum, Curator David Berman, explains that most people do not know how rare such fossil evidence is. “Most reconstructed dinosaur skeletons, like our own famous Diplodocus, are composites—made up of the bones of several animals. Having one complete specimen, like our juvenile Camarasaurus, is extraordinary.” Chris Beard adds that no matter how much money a museum has today, and how badly it may want the real thing, it’s usually impossible. “If you want the Mona Lisa, that object cannot be obtained because it hangs in the Louvre,” Beard says. “We have our own Mona Lisas in Dinosaur Hall.”

Dinosaurs in Their World will feature abundant fossil evidence of the biodiversity on land and at sea throughout the Mesozoic Era. And its exhibits will, of course, include great models, reconstructions, dramatic graphics, and a small theater.

But who are the real stars of the show? The fossils. Large or small, plant or animal, each is evidence of the real worlds that existed millions of years before us.

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