While many dinosaurs towered above trees and stood high in the air. A smaller, bird-like class of dinosaurs have been found. The Eoraptor lived during the late Triassic period and measured just 3 feet long. The Deinonychus was just 4 feet tall at its shoulder and weighed about 175 lbs.
The size of a chicken, the Compsognathus was one of the smallest dinosaurs. With short arms and a long tail, the Compsognathus was 4 feet long and weighed under 7 lbs.
About the size of an ostrich, the Unenlagia is considered the most bird-like dinosaur due to its wing-like forearms and ability to move them up and down in a flapping motion.
The Velociraptor has been portrayed larger in Hollywood movies but actually measured just 3 feet tall. With an s-shaped neck and long, thin legs, the Velociraptor could run 40 mph.
A small, 9-foot-tall predator, the Coelophysis is known as the "Hollow Form" due to its hollow, light bones. The Coelophysis had a pointed head and small, serrated teeth. Two types of Coelophysis have been identified: robust and gracile.
Known as the "Great Lizard," the Megalosaurus was the first dinosaur fossil ever found and the first to be given a scientific name. It was discovered in England in 1676. The Megalosaurus had a short neck, long tail, serrated teeth and short arms. It measured up to 30 feet long and stood 10 feet tall.
The Dilophosaurus lived during the Jurassic period and measured 20 feet long and 5 feet tall at the hip. It had a dewclaw and claws on its fingers and toes.
Known as the "Lizard from Alberta" because the first Albertosaurus bones were discovered in Canada in 1884 and most of this dinosaur's bones have been found in Alberta, Canada, the Albertosaurus is a relative of the Tyrannosaurus Rex. The Albertosaurus measured 30 feet long and 11 feet tall. It weighed up to three tons and walked on two legs. Not unlike the Tyrannosaurus Rex, the Albertosaurus had saw-like teeth and clawed, 3-toed feet.
The Tyrannosaurus Rex stood up to 20 feet tall but had short, 3-foot-long arms. It weighed up to 7 tons and lived during the late Cretaceous period, between 85 and 65 million years ago. This dinosaur had bird-like feet with 3 clawed toes.
The Utahraptor was up to 23 feet long and weighed about a ton. It had bony rods running along its spine.
The largest-known carnivorous dinosaur, the Spinosaurus weighed up to 9.9 tons and was characterized by a large sail on its back. The Spinosaurus had straight, knife-like teeth and the longest head of any known carnivorous dinosaur, which measured 6 feet in length.
Known as the "Different Lizard," the Allosaurus was the largest carnivorous dinosaur in North America during the late Jurassic Period. The Allosaurus walked on two legs and had a large tail, a bulky body and heavy bones. This dinosaur had 6-inch claws on its hands and measured 38 feet long and 16.5 feet tall
The longest carnivorous dinosaur was the Giganotosaurus which measured 46 feet long and weighed about 8 tons. It was 12 feet tall at the hips. Its name means "giant Southern reptile."
The newest of the large dinosaurs discovered is the Suchomimus tenerensis and is believed to have been a 12-foot-tall fish-eating dinosaur. The Yangchuanosaurus walked on two large legs and weighed 5,200 lbs. It measured 33 feet long.