According to some scientists, a massive asteroid plowed into the planet approximately 66 million years ago. It sent ash into the atmosphere and provoked a period of such severe climate change that 75 percent of all plant and animal species, including all non-avian dinosaurs, suddenly disappeared.
But were these species doing well or doing poorly in the period prior to their demise? In other words, were dinosaurs increasing or decreasing in diversity in the years ahead of the asteroid?
