National Geographic : 1954 May
We Captured a 'Live' Brontosaur 707 Ancient Footprints in Texas Rock Bring to Life a Grim Prehistoric Drama and Help Answer a Tantalizing Scientific Riddle BY ROLAND T. BIRD HIS story really begins 135,000,000 years ago. I didn't enter it until the fall of 1938. Above me in one of the huge halls of New York's American Museum of Natural History towered the gigantic skeleton of a brontosaur, typical of the sauropod dinosaurs. Some of these plant eaters were the largest animals that ever walked the earth. Fifteen feet high at the hips and nearly 70 feet in length, the museum's famous brontosaur was truly awe inspiring. Visitors milled past, gesticulating, gaping. The brontosaur's relatively small head, no larger than a bushel basket, was suspended eight feet above me at the end of the great snakelike neck. The forelegs rose like heavy pillars beneath the forward end of the huge rib-enclosed body cavity. I could have walked easily beneath the belly. To me it always suggested a hayloft, for it must have held prodigious amounts of vegetation pulled from the earth with the brontosaur's peglike teeth. The hind legs stood with knees level with my head; from the high-thrust rump near the ceiling drooped the tail, its slender tip lying some 30 feet farther on. Could the Brontosaur Walk? It excited me to imagine this mountain of animal, weighing perhaps 30 tons, walking into the hall alive. But in that vivid apparition I saw only what I wanted to see; how he actually had moved in life was still a mystery. Early paleontologist 0. C. Marsh had named him Brontosaurus, meaning "thunder lizard," on the dramatic assumption that the ground thundered under his tread. But had this dinosaur actually been too big to have walked on land? The legs of a dino saur were very large, but it was hard to be lieve they had borne so many tons. Had he crawled, instead, like an alligator, with legs projecting laterally? Or had he lived his whole life in the water? Scientists were uncertain. It is even possible to "prove" mathemati cally that a brontosaur could have grown too big for his legs to have supported him on land. If a growing sauropod doubled in length, his weight would increase eight times, though his legs-if they grew in proportion-would become only four times as strong. Nostrils of a brontosaur skull, set high up on the crown, suggest a life spent largely in water, for the dinosaur could have breathed with just the top of the head above the surface. When thus immersed and buoyed up, his great body would have floated readily. I passed the rounded forefeet, each pro vided with a long claw on the inner toe. I approached the hind feet, from which the term "sauropod," or "lizard foot," originated. The framework of each contained five meta tarsal bones of the toes, three of them termi nating in heavy claws. What function had these feet served if the dinosaur had not walked? It was difficult to imagine an animal always living in water not eventually losing such appendages in favor of fins or flippers. Preyed Upon by Dagger-toothed Foes Elsewhere about the hall stood other dino saurs, the various plant eaters and flesh eaters, large and small, some with flesh tearing dagger teeth, some with defensive horns, some with great plates of dermal armor. But the brontosaur seemed not to have been provided by Nature with any offen sive or defensive device other than tremendous bulk. As I walked out, I could not help but won der what a plant-eating brontosaur's chances might have been if caught on land by one of the huge theropod dinosaurs, the prehis toric flesh eaters. The Author Roland T. Bird began his career in the natural sciences at the age of 9, when he helped his entomolo gist father collect moths and butterflies. Later he turned to dinosaurs, entering that field under Dr. Barnum Brown. About 80 tons of dinosaur bones and fossil-bearing rock, now in the American Museum of Natural History and other institutions, are the re sults of their expeditions together throughout the western United States and Canada. During World War II, Mr. Bird's knowledge of fossil-bearing rocks helped him serve as a geologist in the Federal Gov ernment's quest for uranium.