Kinds of Dinosaurs
Dinosaurs are divided into two orders---the Saurischia (derived from the Greek for lizard-hipped) and Ornithischia (birdhipped). The saurischians had hips that resembled those of lizards, while the ornithischians' hips resembled those of birds.
are divided into two groups---the theropods and sauropods. With few exceptions, theropods walked on their hind legs and used their forelimbs for grasping. Some theropods were small, others very large. Nearly all were meat-eaters and had long, pointed teeth. Many scientists believe that certain theropods evolved into birds. Examples of theropods are Tyrannosaurus and Allosaurus.
Orinthomimus was a very fast dinosaur of the Cretaceous period.Tyrannosaurus, or Tyrannosaurus rex, was probably the most ferocious of all dinosaurs. Fifty feet (15 m) long and weighing about 8 tons (7,300 kg), it was the largest meat-eater ever to live on land. Allosaurus was also a ferocious dinosaur. It was about 30 feet (9 m) long.
Tyrannosaurus rex was a theropod fifty feet long, weighing about eight tons.Sauropods walked on all four feet and had massive legs. Their teeth were suited only for eating soft, juicy plants. Among the sauropods were the largest land-dwelling animals. Examples of sauropods are Apatosaurus, Brachiosaurus, and Diplodocus.
Apatosaurus was for many years called Brontosaurus and is still sometimes called by that name. It was from 60 to 70 feet (18 to 21 m) long with a relatively short body and a long neck and tail. Its weight was probably 30 to 35 tons (27,200 to 31,800 kg). Another giant sauropod, 80 feet (24 m) long, was Brachiosaurus. Unlike other sauropods, it had forelegs larger than its hind legs and the body sloped toward the tail. The nostrils were above the eyes. Brachiosaurus was the largest dinosaur; some probably weighed more than 80 tons (72,600 kg). Diplodocus was longer, but not as heavy as Brachiosaurus. It was about 87 feet (27 m) long.
The brachiosaurus was a huge, herbivorous dinosaur.were plant-eaters. Some walked on their hind legs, others on all fours. Most ornithischians developed structures for defense against their enemies---primarily the meat-eating dinosaurs. Ornithischians are divided into four groups---the armored, plated, horned, and duck-billed dinosaurs.
Ankylosaurus, a typical armored dinosaur, had a broad, squat body with strong, stumpy legs. It was about 33 feet (10 m) long, 6 feet (1.8 m) wide, and about 4 feet (1.2 m) tall. The back, sides, and tail were covered with rows of raised bony plates. The tail ended in a large, clublike mass of bone that was probably used as a weapon.
Stegosaurus, a plated dinosaur, was more than 25 feet (8 m) long and weighed 2 tons (1,800 kg). It had massive hind legs that were twice the length of the forelegs. Extending down its back was a double row of triangular bony plates standing upright. The largest plates, above the hind legs, were 3 feet (90 cm) high. The plates possibly served as protection or as a means of regulating body temperature by heat exchange with the atmosphere. The tail had four spikes, and was probably used as a weapon.
Stegosaurus was a plated dinosaur more than twenty-five feet long.Triceratops was the largest of the horned dinosaurs. The largest known specimen was 30 feet (9 m) long and weighed approximately 12 tons (10,900 kg). It had three horns---a short one above the snout and a long one above each eye. The head was protected by a large bony structure that extended back over the neck and shoulders.
Anatosaurus, a duck-billed dinosaur, had an elongated skull with a broad, flattened snout and a toothless beak. It was about 30 feet (9 m) long and 13 feet (4 m) tall and weighed about 4 tons (3,600 kg). Anatosaurus usually walked on all four legs. Fossil remains show that it ate twigs, seeds, and fruits and that it had a thick, leathery hide.
Dinosaurs of the of the Cretaceous Period lived roughly 65 million to 150 million years ago.
Find Your Perfect Pet
Comments