Dinosaur skull
Thousands of dinosaur fossils have been found in Arizona, making it one of North America's dinosaur hot spots. Fossil hunters began finding and naming dinosaurs in the mid-19th century, and the discoveries continue even today. From the early Triassic period (245 million years ago) to the late Cretaceous period (100 million years ago), dinosaurs roamed the area that is now Arizona, leaving behind a puzzle that scientists strive to put together.
Ammosaurus
From the early Jurassic period, the ammosaurus was a long-necked, small-headed herbivore. It was about 14 feet long and had a bulky body and long tail. Ammosaurus fossils have been found in Arizona, Connecticut and Nova Scotia, Canada.
Chindesaurus
The chindesaurus was a smaller dinosaur, measuring about 6 feet in length. Chindesaurus fossils have been found in the American Southwest, including Arizona and New Mexico. A fast-moving biped, this dinosaur probably weighed only about 65 pounds and lived during the late Triassic period.
Coelophysis
Hundreds of coelophysis fossils have been found in Arizona, New Mexico, and Utah. The coelophysis dinosaurs lived in the late Triassic period. These dinosaurs were carnivores and possibly scavengers, and they hunted in packs. Fossilized reptiles and fish have been found in stomachs of coelophysis dinosaurs, and they had light, hollow bones.
Dilophosaurus
Dilophosaurus dinosaurs lived during the early Jurassic period, and their fossils have been found in Arizona and China. The dilophosaurus was a fast-running carnivore and had bird-like footprints. The first dilophosaurus fossils were found in Arizona in the 1940s.
Massospondylus
The massospondylus was a large herbivore that lived in the early Jurassic period. It was about 13 feet long and had a long neck and very long tail. Like modern birds, the massospondylus swallowed small pebbles to help it digest its food. It had a five-fingered hands with a thumb-like appendage, which it may have used to tear its food.
Scutellosaurus
The scutellosaurus lived during the early Jurassic period in what is now Arizona. Only 18 inches tall, the scutellosaurus was an herbivore that probably weighed about 22 pounds. It could walk on two or four legs and had hundreds of bony plates along its back and tail.
Sonorasaurus
Discovered by geology student Richard Thompson in 1995, the sonorosaurus was a large, plant-eating dinosaur measuring about 50 feet long. It lived in the middle Cretaceous period. It had a giraffe-like neck, tiny head, and large, bulky body.
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