Jan 7, 2026 · 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. …

Jan 7, 2026 · Dinosaur - Extinction Causes, Evidence, & Theory: The mass extinction of dinosaurs 66 million years ago remains a misconception; the fossil record shows that …

Dinosaurs roamed the Earth for an impressive span of about 165 to 180 million years. They perished in a mass extinction event about 66 million years ago.

Dec 10, 2025 · Federalism, mode of political organization that unites separate states or other polities within an overarching political system in a way that allows each to maintain its own …

5 days ago · House of Representatives, one of the two houses of the bicameral United States Congress, established in 1789.

Dec 9, 2022 · Food web, a complex network of interconnecting and overlapping food chains showing feeding relationships within a community. A food chain shows how matter and energy …

5 days ago · Pollution is the addition of any substance or form of energy to the environment at a rate faster than it can be dispersed or stored in a harmless form. The major kinds of pollution …

Dec 4, 2025 · Gene, unit of hereditary information that occupies a fixed position on a chromosome. Genes achieve their effects by directing the synthesis of proteins. They are …

Nov 27, 2025 · cognition, the states and processes involved in knowing, which in their completeness include perception and judgment. Cognition includes all conscious and …

Dec 30, 2025 · The Invasion of Poland by Nazi Germany occurred from September 1 to October 5, 1939, and marked the start of World War II.