The Cretaceous Period

The Cretaceous Period

Duration: 145 to 66 million years ago (lasted 79 million years) Category: It is a Period, part of the Mesozoic Era

What Was the World Like?

Before the asteroid struck, the Earth was much warmer than today, with no polar ice caps and high sea levels that covered large parts of the continents. Thick forests and thriving vegetation due to the high carbon dioxide levels, creating a greenhouse effect that made the planet humid and tropical. Dinosaurs dominated land and air, with powerful predators like Tyrannosaurus rex hunting plant-eaters such as Triceratops and Hadrosaurs. Oceans were home to massive marine reptiles like Mosasaurus, alongside early sharks and ammonites. The skies were filled with Pterosaurs, large flying reptiles, while small mammals and birds were beginning to evolve in the shadows of the dinosaurs. Earth’s continents were still shifting due to plate tectonics, and shallow seas, such as the Western Interior Seaway, covered parts of North America.

Major Event: The Cretaceous-Paleogene Extinction

Around 66 million years ago, a 6-mile-wide asteroid struck Earth near what is now Chicxulub, Mexico, at a speed of about 45,000 miles per hour. The impact was 10 billion times more powerful than an atomic bomb, creating a crater over 90 miles wide and 12 miles deep. The explosion instantly vaporized everything within hundreds of miles, sending fireballs of molten rock into the atmosphere. The impact triggered massive wildfires across the planet, as debris rained down. A 1,500-foot-high tsunami swept across oceans, destroying coastal ecosystems. Shockwaves from the impact caused earthquakes and volcanic eruptions, further devastating life on Earth. The explosion sent massive amounts of dust and sulfur into the sky, blocking out sunlight for months or even years, leading to what scientists call a "nuclear winter."

FUn facts!

-The impact instantly created a fireball hotter than the Sun, igniting wildfires thousands of miles away! -The asteroid caused a 1,500-foot tsunami that slammed into coastlines worldwide -Ash and dust blocked sunlight for months, dropping temperatures like a sudden winter. -If the asteroid had hit just a few minutes earlier or later, dinosaurs might have survived in another part of the world. -Sulfur from the impact mixed with the air, creating acid rain that poisoned oceans.