Dec 22, 2025 · 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. Most died …

Dec 12, 2025 · Tyrannosaurus rex, species of large predatory theropod dinosaurs that lived during the end of the Cretaceous Period (about 66 million years ago) known from fossils found in the United …

Dec 21, 2025 · Triceratops, large quadrupedal plant-eating dinosaur that had a frill of bone at the back of its skull and three prominent horns. Fossils date to the final 3 million years of the Cretaceous Period …

Theropod, any member of the dinosaur subgroup Theropoda, which includes all the flesh-eating dinosaurs. Theropods were the most diverse group of saurischian (“lizard-hipped”) dinosaurs, …

Quetzalcoatlus is a genus made up of two species of giant pterosaurs, classified in the family Azhdarchidae, that lived during the Maastrichtian Age (72.1 million to 66 million years ago) of the …

Nov 8, 2025 · La tarde del dinosaurio (1976; “The Afternoon of the Dinosaur”) is a volume of stories with a prologue by Cortázar. Witty El museo de los esfuerzos inútiles (1983; The Museum of Useless …

Take this Science quiz at Encyclopaedia Britannica to test your knowledge of dinosaurs.

Ornithischian, any member of the large taxonomic group of herbivorous dinosaurs comprising Triceratops and all dinosaurs more closely related to it than to birds. The ornithischians (meaning …