Another mystery concerns dinosaurs extinction 65 million years ago. If they died off due to a meteorite or comet smacking the earth and throwing up dust to block out the sun, then why did certain other reptiles, including crocodiles, turtles, and snakes, survive? Indeed, why did some other non-dinosaur types survive including primitive mammals from which humans later evolved? Since most paleontologists now think that birds are the living descendants of dinosaurs, why and how did they survive?
A few paleontologists have suggested that some type of disease may have played a factor. Others point to new evidence of possible climatic changes from increased volcanism. Still others have noted that changing vegetation could have been unfavorable to some types of dinosaurs. The latest thinking by paleontologists is that the dinosaurs died off from a combination of causes, with both the numbers and types of dinosaurs decreasing before the final extinction.