Dinosaurs first appeared on Earth about 228 million years. They varied greatly in shape and size. Some weighed more than 80 tons and were more than 120 feet long. Others were the size of a finch and weighed as little as 8 ounces. Most dinosaurs became extinct at the end of the Cretaceous period 65 million years ago, but one group survived: modern birds, which share a common ancestor with non-avian dinosaurs.
Over millions of years, ocean basins open and close, continents move and change shape, and mountains are pushed up and eroded away. Such dynamic processes continually reshape the surface of the Earth. The movement of rigid plates on the Earth’s surface, known as plate tectonics, is the cause of these changes. Volcanic eruptions and earthquakes are dramatic hints of the great movements that take place over the vastness of geological time.
The Universe is all the matter, energy, and space that exists, and the observable universe is the part that we can see. While there are still great mysteries about how it all began and evolved, we are living in an age of rapid cosmic discovery. Astrophysicists use observations from telescopes on the ground and in space, spacecraft return data from the outer reaches of our solar system, models based on the mathematical laws of physics reveal the structure and history of the universe and our place in it. These simulations, videos, and essays, cover the formation, evolution, and properties of stars, planets, galaxies, and the universe.
Evidence collected during the five-year voyage of the HMS Beagle led to Charles Darwin’s revolutionary theory that all species, including humans, adapt to different environments and change over time through the process of natural selection. Since a Neanderthal skullcap was discovered in 1856, thousands more fossils have helped paleoanthropologists piece together the story of our ancient ancestors, from early hominins who lived more than six million years ago to modern Homo sapiens, who evolved 200,000 to 150,000 years ago. In the 1990s, geneticists joined the effort, using DNA to shed light on how modern humans are related to one another and what makes our species unique. These videos and essays cover the evidence for human evolution and how understanding evolutionary biology benefits human health and wellbeing.
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