3 days ago · Dinosaur, the common name given to a group of reptiles, often very large, that first appeared roughly 245 million years ago and thrived worldwide for nearly 180 million years.

3 days ago · Dinosaur - Extinction, Fossils, Evolution: Dinosaurs lived in many kinds of terrestrial environments, and although some remains, such as footprints, indicate where dinosaurs actually …

Dinosaur, the common name given to a group of reptiles, often very large, that first appeared roughly 245 million years ago (near the beginning of the Middle Triassic Epoch) and thrived worldwide for …

3 days ago · Dinosaur - Evolution, Classification, Extinction: After dinosaurs were recognized as a new type of fossil animal, popular fascination with them reached a peak in the 1850s with the first …

Dec 22, 2025 · Dinosaur - Reptiles, Extinction, Fossils: The chief difference between the two major groups of dinosaurs is in the configuration of the pelvis. The two dinosaurian orders were named …

3 days ago · Dinosaur - Extinction Causes, Evidence, & Theory: The mass extinction of dinosaurs 66 million years ago remains a misconception; the fossil record shows that dinosaurs were already in …

This initial period of dinosaur evolution set the stage for their dominance in the Mesozoic Era. Throughout the Mesozoic Era, which lasted from about 252.2 million to 66 million years ago, …

dinosaur, Any of the extinct reptiles that were the dominant land animals during most of the Mesozoic Era (251–65.5 million years ago).

These lizardlike reptiles got the name dinosaur from Greek words that mean “terrible lizard.” The last dinosaurs became extinct, or died out, about 65.5 million years ago.

Dec 12, 2025 · Tyrannosaurus rex was a large dinosaur. Scientists estimate that the largest adults weighed 4,000 to 7,000 kg (about 9,000 to 15,000 pounds) and measure more than 12 meters (about …