The Chicxulub impact and demise of dinosaurs
A meteor crashed into the Yucatan 66 million years ago, wreaking havoc on earth’s environment, leading to the final demise of the large dinosaurs. Geologists at the University of Texas are using log data from commercial drilling operations in the Gulf of Mexico to measure and analyze that event.
Other researchers looking at the number of extant species over time argue that dinosaur species were declining prior to the Chicxulub impact. (Cite.) I’m a bit skeptical. At most, it seems to me, they are counting genera. It can be hard to distinguish bird species from close study of living ones. We can’t study dinosaur behavior or biochemistry directly. So who knows how many actual species there were, or how much variation there may have been in the small, that later would have emerged in the large?