Allosaurus, which predated Tyrannosaurus Rex by some 85 million years, was the largest land predator of the late Jurassic Period.
Dinosaur Days 3: Allosaurus
In the 1969 cult classic The Valley of Gwangi -animated by stop-motion maestro Ray Harryhausen -a circus owner and his crew abduct an Allosaurus from a hidden Mexican valley where prehistoric beasts have miraculously defied extinction. But the new owners are unable to contain their monster for long, who goes on a rampage, devouring a midget and slaughtering a full-grown elephant. Finally the dinosaur’s captors manage to trap the mighty carnivore in a burning building, where its agonized death bellows rise over the crackling of the terrible conflagration.
This was fiction, but the fact is that Allosaurus was the largest land carnivore of its time. The 38-foot long, 17-foot tall Allosaurus even towered over fellow predators like the horn-nosed Ceratosaurus, who was a fairly intimidating 10-12 feet in height and 15 to 20 feet in length. Four different species of Allosaurus have been classified, and the largest, Allosaurus Amplexus, may have weighed up to five tons. Allosaurus walked on two bird-like feet, balancing with its tail, and its short forearms ended in three six-inch talons. The three-foot long head contained dozens of serrated teeth. Above the eyes were bony ridges. A single Allosaurus probably was no match for the gargantuan herbivore Diplodocus, who was 90 feet from head to tail, or the "thunder lizard" Brontosaurs (70 feet), but Allosaurus may have hunted in packs, and was certainly a threat to young, injured or old sauropods. Even the spike-tailed Stegosaurus probably gave this carnosaur a wide berth, as one bite from Allosaurus could have easily severed the plant-eater’s tiny head.
Allosaurus’ heyday was during the late Jurassic Period, about 150 to 140 million years ago, where this theropod dinosaur trolled the lush swamps and sub-tropical forests in search of prey. The earth’s geography was very different; the great land mass known an "Pangea" (Greek for "all land") had gradually broken apart, causing the continents to slowly drift farther and farther from one another. Greenland was sandwiched between the eastern coast of North America and the western coast of Europe, and South America and Africa were about one-third their current distance. Huge sharks and marine crocodiles swam through the oceans.
Allosaurus was discovered and named in the 1870’s by paleontologist Othniel C. Marsh. Allosaurus means "different lizard," so called by Marsh because of the creature’s lighter vertebrae and s-shaped neck (Enchanted Learning). A great number of Allosaurus fossils, as well as those of Brontosaurus and many other dinosaurs, have been found in the Morrison Formation, a vast expense of rock extending over 12 states, primarily Montana, Wyoming Colorado and New Mexico, as well as into the Canadian provinces of Saskatchewan and Manitoba. This quarry is located on the former coast of a shallow sea that covered much of western North America about 200 million years ago. The soft sand at the edge of this ancient ocean provided an ideal environment for the preservation of fossils. A nearly complete Allosaurus skeleton was discovered by a Colorado rancher in 1883.
Sources
Benton, Michael. The Dinosaur Encyclopedia. New York:Wanderer Books, 1984. 20, 26-27, 37.
Bakker, Robert T. The Dinosaur Heresies. New York: William Morrow and Co., Inc., 1986. 34-38, 108, 264.
Hoesch, William A. and Steven A. Austin. "Dinosaur National Monument: Jurassic Park or Jurassic Jumble?" Institute for Creative Research. 8 April 2008.
"Allosaurus." Enchanted Learning. 8 April 2008.
