About 150 million years ago during the Jurassic Period, the ground shuddered as though it would rip apart from an earthquake. It thundered as though pummeled by a crushing landslide. It jolted as if a volcano were blasting scorching lava skyward. Yet the culprit was not a natural disaster, but the mighty stomping of one of the most colossal animals to populate North America, the legendary Apatosaurus.
Originally called Brontosaurus, or "thunder lizard," due to a labeling mistake on a similar fossil specimen, Apatosaurus means "deceptive lizard." Nothing like the family pet on "The Flintstones," Apatosaurus was 70 feet long, had a shoulder height of 12 feet, a 17-foot neck and weighed 30 tons – as much as five full-grown elephants. It's likely that its tail weighed several tons, to balance the enormous dinosaur when it walked, and was about 30 feet long, to help distribute the creature's bulk. In order to maintain its massive size, Apatosaurus was constantly seeking food, feeding day and night.
Despite its formidable appearance, this gentle giant was an herbivore, or plant-eater, that roamed Utah, Colorado and Wyoming. It had chisel-like teeth that aided in stripping and consuming foliage such as conifers, various other tree leaves and ferns, and thick lips that also assisted in the food gathering process. It may have used its powerful tail as a third leg to access tall vegetation. Some paleontologists question how Apatosaurus could eat enough to sustain a 30-ton body. It's speculated that the lizard may have eaten a tremendous amount of plant materials whole, which were then ground up by stones called gastroliths that it swallowed to help digest dense plant matter or chunks that hadn't been chewed. This immense dinosaur also slowly lumbered on its yard-long feet and pillar-thick legs, possibly conserving energy from the food that it ate.
Apatosaurus was a sauropod (meaning "lizard-footed"), a class of huge, four-legged, long-necked, long-tailed, plant-eating dinosaurs. They were distinguished by small heads and a small brain, blunt teeth and large bellies for digesting vast quantities of plants. They plodded along on four massive, five-toed legs. On the upper sections of their skulls were nostrils, which were often very close to their eyes. Several of the later sauropods even had body armor.
Apatosaurus held their heads – and thus their brains – far above their hearts. This required them to have large, robust hearts and exceptionally high blood pressure in order to propel blood up the lengthy neck to the head and brain (although their intelligence was among the lowest of the dinosaurs, and their brain one of the smallest). Pumping an adequate amount of oxygenated blood to these regions demanded an enormous, powerful heart, immensely high blood pressure and expansive, muscular blood vessels with numerous valves, in order to stave off back-flow of blood. It's likely that Apatosaurus' blood pressure was three or four times as high as the average human's.
At the other end of Apatosaurus was its heavy, formidable tail, which could be used to whip the rare predator that dared to attempt an attack. However, hatchlings were more vulnerable, but could run quickly on their hind legs, like a modern basilisk lizard, to avoid becoming a carnivore's dinner, staying close to adults for protection. These babies hatched from massive eggs that were up to one foot wide, which were laid as the adult was walking. Not exactly parents of the year, it's likely Apatosaurus did not take very good care of their eggs.
However, they could take care of themselves in a brawl. The biggest North American meat-eater at that time was Allosaurus, which stood 15 feet tall, while Apatosaurus could raise its head 17 feet in the air. With height on its side, Apatosaurus' head and neck couldn't be attacked by carnivores like Allosaurus. And predators generally steered clear of Apatosaurus' immense, clawed feet and lashing tail. Computer modeling has indicated that Apatosaurus' tail could create a whip-like snapping sound topping 200 decibels, on a par with the volume of a cannon.
Studies have suggested that it only took Apatosaurus about 10 years to reach full size, and that some of these enormous lizards may have lived 100 years. Even though Apatosaurus has been extinct for millions of years, it lives on in science, education, fantasy – and the imagination.