Science / Biology / Dinosaurs: Any of the Mesozoic diapsids (once considered to be reptiles) belonging to the groups designated as ornithischians and saurischians.


Science / Biology / Extinction: The elimination of all individuals in a group, both by natural (dinosaurs, trilobites) and human-induced (dodo, passenger pigeon, liberals [:)]) means. MORE


Science / Biology / Thecodonts: An informal term for a variety of Permian and Triassic reptiles that had teeth set in individual sockets. Small, bipedal thecodontians are the probable ancestors of dinosaurs. MORE


Science / Biology / Birds: Taxonomic class of terrestrial vertebrates that are characterized by endothermy and feathers; descended from some group of reptiles (or possibly dinosaurs). MORE

Mesozoic Era

Science / Biology / Mesozoic Era: The period of geologic time beginning 245 million years ago and ending 65 million years ago; the age of the dinosaurs and cycads, the Mesozoic falls between the Paleozoic and Cenozoic Eras and include MORE

Triassic Period

Science / Biology / Triassic Period: The first period of the Mesozoic Era between 225 and 185 million years ago. Pangaea began to breakup during this time. The ancestors of dinosaurs were present, as were early mammals and mammal-like re MORE

Cretaceous Period

Science / Biology / Cretaceous Period: The geologic period between the Jurassic Period (140 milliojn years ago) and the Tertiary Period (beginning 65 million years ago). The Cretaceous was marked by a mass extinction that closed the period MORE