Even before the great asteroid strike, were dinosaurs on the verge of extinction? Researchers provide fresh By Katie Hunt , Shown here is an artist's reconstruction of what the North American environment may have looked like 66 million years ago. Davide Bonadonna In paleontology, there has long been a controversy about: Were dinosaurs already on the verge of extinction when the space rock struck Earth 66 million years ago, or were they flourishing when the asteroid struck one fateful spring day? A group of scientists examined the fossil record of North America, concentrating ...