DINOSAURS WENT EXTINCT!
Cretaceous–Tertiary extinction event (End Cretaceous or K-T extinction) - 70 to 65 Ma at the Cretaceous.Maastrichtian-Paleogene.Danian transition interval. The K–T event is now called the Cretaceous–Paleogene (or K–Pg) extinction event by many researchers. About 17% of all families, 50% of all genera and 75% of species went extinct. In the seas it reduced the percentage of sessile animals to about 33%. The boundary event was severe with a significant amount of variability in the rate of extinction between and among different clads. Mammals and birds emerged as domininant land vertebrates in the age of new life.
As originally proposed in 1980 by a team of scientists led by Luis Alvarez and his son Walter, it is now generally thought that the K–Pg extinction was caused by the impact of a massive comet or asteroid 10 to 15 km (6 to 9 mi) wide, 66 million years ago, which devastated the global environment, mainly through a lingering impact winter which halted photosynthesis in plants and plankton. The impact hypothesis, also known as the Alvarez hypothesis, was bolstered by the discovery of the 180 km Chicxulub crater in the Gulf of Mexico's Yucatán Peninsula in the early 1990s, which provided conclusive evidence that the K–Pg boundary clay represented debris from an asteroid impact.