Science, Tech, Math › Animals & Nature 12 Frequently Asked Dinosaur Questions Be a Dinosaur Know-It-All With This Who, What, and Where Share Flipboard Email Print Animals & Nature Dinosaurs Basics Paleontologists Carnivores Dinosaurs & Birds Herbivores Marine Reptiles Prehistoric Mammals Amphibians Birds Habitat Profiles Mammals Reptiles Insects Marine Life Forestry Evolution View More By Bob Strauss Science Writer B.S., Cornell University Bob Strauss is a science writer and the author of several books, including "The Big Book of What, How and Why" and "A Field Guide to the Dinosaurs of North America." our editorial process Bob Strauss Updated September 27, 2019 Why were dinosaurs so big? What did they eat, where did they live, and how did they raise their young? The following are a dozen of the most frequently asked questions about dinosaurs with links to the best answers for further exploring. Learning about dinosaurs can be tricky—there are so many of them, and there's so much to know—but it's a lot easier when the details are portioned out in a logical way. 01 of 12 What Is a Dinosaur? Tyrannosaurus rex is one of the most well-known of all dinosaurs. Wikimedia Commons People sling the word "dinosaur" around an awful lot, without knowing precisely what it means—or how dinosaurs differed from the archosaurs that preceded them, the marine reptiles and pterosaurs with which they coexisted, or the birds to which they were ancestral. In this article, you'll learn what experts really mean by the word "dinosaur." 02 of 12 Why Were Dinosaurs So Big? The plant-eater Nigersaurus or (Niger reptile) from the Cretaceous period was about 30 feet long and weighed 4 tons. Wikimedia Commons The biggest dinosaurs—four-legged plant-eaters like Diplodocus and two-legged meat-eaters like Spinosaurus—were bigger than any other land-dwelling animals on Earth, before or since. How, and why, did these dinosaurs attain such enormous size? Here's an article explaining why dinosaurs were so big. 03 of 12 When Did Dinosaurs Live? This diagram shows the Mesozoic Era broken into the three periods, beginning with the most recent at the top: Cretaceous, Jurassic, and Triassic. ThoughtCo / UCMP Dinosaurs ruled the Earth longer than any other terrestrial animals, all the way from the middle Triassic period (about 230 million years ago) to the end of the Cretaceous period (about 65 million years ago). Here's a detailed overview of the Mesozoic Era, the period of geologic time comprising the Triassic, Jurassic, and Cretaceous periods. 04 of 12 How Did Dinosaurs Evolve? Tawa hallae is considered an evolutionary link between primitive carnivores and modern birds. ThoughtCo / Nobu Tamura As far as paleontologists can tell, the first dinosaurs evolved from the two-legged archosaurs of late Triassic South America (these same archosaurs also gave rise to the very first pterosaurs and prehistoric crocodiles). Here's an overview of the reptiles that preceded the dinosaurs, as well as the story of the evolution of the first dinosaurs. 05 of 12 What Did Dinosaurs Really Look Like? The face of the plant-eating Jeyawati dinosaur from the Cretaceous period. ThoughtCo / Lukas Panzarin This might seem like an obvious question, but the fact is that depictions of dinosaurs in art, science, literature, and movies have changed radically over the last 200 years—not only how their anatomy and posture are depicted but also the color and texture of their skin. Here's a more detailed analysis of what dinosaurs really looked like. 06 of 12 How Did Dinosaurs Raise Their Young? A titanosaur egg from one of the largest dinosaurs that ever lived. Getty Images It took decades for paleontologists just to figure out that dinosaurs laid eggs—they're still learning about how theropods, hadrosaurs, and stegosaurs raised their young. First things first, though: Here's an article explaining how dinosaurs had sex and another article on the subject of how dinosaurs raised their young. 07 of 12 How Smart Were Dinosaurs? Troodon is considered to be among the smartest dinosaurs because it had a large brain for its small size. ThoughtCo Not all dinosaurs were as dumb as fire hydrants, a myth that has been perpetuated by the spectacularly small-brained Stegosaurus. Some representatives of the breed, especially feathered meat-eaters, may even have attained near-mammalian levels of intelligence, as you can read for yourself in "How Smart Were Dinosaurs?" and the "10 Smartest Dinosaurs." 08 of 12 How Fast Could Dinosaurs Run? An Ornithomimus (bird mimic) may have been able to run 43 mph. ThoughtCo / Julio Lacerda In the movies, meat-eating dinosaurs are portrayed as speedy, relentless killing machines, while plant-eating dinosaurs are fleet, stampeding herd animals. The fact is, though, that dinosaurs differed enormously in their locomotive abilities, and some breeds were faster than others. This article explores how fast dinosaurs could really run. 09 of 12 What Did Dinosaurs Eat? A fern-like, seed-bearing cycad with a couple of large cones—food in prehistoric times. Wikimedia Commons Depending on their proclivities, dinosaurs pursued a wide variety of diets: Mammals, lizards, bugs, and other dinosaurs were favored by meat-eating theropods, and cycads, ferns, and even flowers figured on the menus of sauropods, hadrosaurs, and other herbivorous species. Here's a more detailed analysis of what dinosaurs ate during the Mesozoic Era. 10 of 12 How Did Dinosaurs Hunt Their Prey? The 8-inch arms and 8-inch claws on the omnivorous Deinocheirus mirificus (Greek for terrible hand) would have been perfect for gathering plants and catching fish. ThoughtCo / Luis Rey The carnivorous dinosaurs of the Mesozoic Era were equipped with sharp teeth, better-than-average vision, and powerful hind limbs. Their plant-eating victims evolved their own unique set of defenses, ranging from armor plating to spiked tails. This article discusses the offensive and defensive weapons used by dinosaurs, and how they were employed in combat. 11 of 12 Where Did Dinosaurs Live? A lush riparian forest is where dinosaurs would have congregated. Wikimedia Commons Like modern animals, the dinosaurs of the Mesozoic Era occupied a wide range of geographical regions, from deserts to tropics to polar regions, across all the Earth's continents. Here's a list of the 10 most important habitats prowled by dinosaurs during the Triassic, Jurassic, and Cretaceous periods, as well as slideshows of the "Top 10 Dinosaurs by Continent." 12 of 12 Why Did Dinosaurs Go Extinct? An aerial view of Arizona’s Barringer Meteor Crater is a small-scale example of the underwater Chicxulub crater in the Yucatan Peninsula—the meteor responsible for the K-T extinction event. U.S. Geological Survey At the end of the Cretaceous period, dinosaurs, pterosaurs, and marine reptiles seemed to have disappeared off the face of the Earth virtually overnight (though, in fact, the process of extinction may have lasted for thousands of years). What could have been powerful enough to wipe out such a successful family? Here's an article explaining the K-T extinction event, as well as "10 Myths About Dinosaur Extinction."