The World’s Largest Dinosaurs, a major exhibition on view at Baylor University’s Mayborn Museum from June 5 to September 26, 2021, explores the amazing biology of a group of uniquely super-sized dinosaurs: the long-necked and long-tailed sauropods.
Organized by the American Museum of Natural History in New York, the exhibition draws on paleo-biological research that looks in part to living organisms to make inferences about how these giants— some of which grew to be longer than 150 feet, or the length of four standard city buses—were able to thrive, as a group, for approximately 140 million years.
Introduction. When visitors enter the exhibition space, they will immediately encounter the enormous head of an Argentinosaurus, considered the world’s largest sauropod. Discovered in Argentina, this dinosaur probably weighed up to 90 tons and measured up to 140 feet long.
Size. This section explores the biological effects of size in animals both huge and tiny and living and extinct. To provide perspective, a 15-foot-tall replica of a Supersaurus hind leg is displayed among models, specimens and bones of living animals such as a hummingbird, dwarf gecko, African elephant and human.
Meet Mamenchisaurus. Standing 11 feet tall at the shoulders and measuring 60 feet long—approximately the size of a tractor-trailer—the centerpiece of this exhibition is a life-sized, fleshed-out model of an 18-year-old female Mamenchisaurus. Though not the largest sauropod, Mamenchisaurus is known for its remarkable 30-foot-long neck, which accounts for fully half of its body size. Textured skin on one side of the model gives visitors a sense of this enormous animal’s appearance; on the other side the animal appears to be dissected, with key organs, including the heart and lung, isolated and modeled at life size. A video projected on the animal’s midsection enables visitors to see how a Mamenchisaurus’s respiratory, circulatory, and digestive systems contributed to its enormous size.
Eat. What did a sauropod eat? How could sauropods possibly get enough food to survive? This section addresses how sauropods developed into hugely efficient eating machines by exploring their “fermentation tank” digestive systems, their herbivorous diet, incisor-like teeth, and the mechanics of ingesting by swallowing vegetation whole.
React. Sauropods had small brains in their relatively small heads. An Apatosaurus brain weighed at most 4 ounces compared to the 48-ounce human brain. This section addresses brain size and debunks the “booster brain” myth, which hypothesized that some sauropods possessed a second “brain” in their tail bone. On display is a cast of half of a Diplodocus braincase, which provided scientists with important clues about the large-scale brain structure of this extinct dinosaur.
Reach. With their crane-like necks, sauropods were able to reach food that other plant eaters could not. This section addresses the biomechanics and adaptive advantages of a long but surprisingly lightweight neck. The intricate structure of sauropod vertebrae is illustrated by a huge cast fossil neck bone; also explored is the effectiveness of long necks as cooling systems.
How Big. Over the course of 140 million years, sauropods evolved into a range of shapes and sizes with varying colors and ornamentation. Through fossil evidence and the study of living animals, scientists have been able to determine the approximate sizes and weights of various species of sauropods. A 60-by-16-foot mural on one wall of the exhibition depicts this group’s diversity.
Babies. Emerging from an egg smaller than a soccer ball, hatchling sauropods grew to an enormous size in a short amount of time. While hatchlings generally weighed less than 11 pounds at birth, within three decades, mature adult sauropods could weigh 10,000 times more, or as much as 55 tons. No other known land animal, bird, or reptile grew at such an exponentially rapid rate. Replicas of eggs from living and extinct animals—an elephant bird, the sauropod Ampelosaurus, the theropod Oviraptor, an osprey, and a ruby-throated hummingbird—are available for visitors to compare and analyze.
Skin. For scientists today, fossilized skin impressions are the only record of what a sauropod’s skin may have looked like. From these impressions, we know that sauropod skin was almost certainly dry and warm, and because dinosaurs had no sweat glands in their skin, they did not perspire. They were covered with small, bumpy and knobby scales that protected the dinosaur’s body and prevented evaporation of water from inside. No sauropods had hair or feathers. On display is a cast osteoderm, or bony skin growth, of a titanosaur, part of a sauropod group that reached the largest sizes and lived between 65 and 71 million years ago.
Beat. Human hearts pump 6.5 quarts of blood throughout the body, whereas a Mamenchisaurus heart pumped 630 quarts of blood. Although no fossilized dinosaur hearts have been discovered, scientists have been able to determine the size and structure of a sauropod heart by studying their closest living relatives—ostriches and crocodilians. A life-sized heart model is on display, and visitors can use a pump connected to a computer interactive to calculate the correct speed and pressure required to circulate blood throughout a sauropod’s large body.
Breathe. A resting human inhales one pint of air per breath, while a Mamenchisaurus took in about 174 pints. On display is a life-sized replica of the enormous and complex breathing system that made that volume possible. To understand sauropod respiratory systems, scientists looked to the breathing and anatomy of birds and crocodilians. These comparisons indicated that the highly efficient lungs of sauropods received oxygen-rich air during inhalation as well as exhalation. This continuous flow enabled a sauropod to spend less energy on breathing.
Fuel. With a diet that may have included horsetails, ginkgos, conifers, and ferns, a Mamenchisaurus needed 100,000 calories per day to survive. In contrast, an adult human needs just 2,200 calories per day. A 5½-foot cube of foliage on display represents how much plant matter—approximately 1,000 pounds—a Mamenchisaurus ate in a single day. An hour’s worth of food is encased in a smaller plexiglass column, while an interactive exhibit invites visitors to “feed” a hungry sauropod.
Who was that dinosaur? Sauropod tracks, which can be found on nearly every continent, have provided some of the best information about the animals’ daily life.
Search. There is still more to understand about sauropods and more specimens to be found. A wire outline of a vertebra hints at the dimensions of what may have been the largest sauropod to ever walk the Earth, Amphicoelias. In 1878, well-known fossil hunter E.D. Cope published detailed drawings and measurements of the specimen, but the fossil itself has since been lost.