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Course: American Museum of Natural History > Unit 1
Lesson 3: Dinosaur extinction- A brief history of mass extinctions
- Discarded theories for dinosaur extinction
- Were dinosaurs undergoing long-term decline before mass extinction?
- Are any dinosaurs still alive today?
- Are any dinosaurs still alive today?
- How did all dinosaurs except birds go extinct?
- How did all dinosaurs except birds go extinct?
- Quiz: Dinosaur Extinction
- Exploration Questions: Dinosaur Extinction
- Answers to Exploration Questions: Dinosaur Extinction
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Discarded theories for dinosaur extinction
Paleontologists are actively investigating what caused all nonavian dinosaurs to die out 65 million years ago. Most agree that the impact of a large asteroid or comet played a major role, while scientists continue to debate how volcanic activity or climate change caused by retreating sea levels might have contributed. Still, paleontologists can say for certain that some proposed explanations for the extinction of nonavian dinosaurs have proven false.
Did dinosaurs...?
Get too big to survive? No. Most of the largest dinosaurs lived millions of years before the mass extinction.
Go extinct because their eggshells got too thin? No. Although some dinosaurs did have unusually thin eggshells, many others did not. Many survivors, including birds (living dinosaurs), crocodiles and turtles, all have thin eggshells.
Die out because mammals drove them to extinction? Did mammals eat all of the dinosaurs' eggs? No. Dinosaurs coexisted with mammals for over 150 million years, so there's no reason to think that mammals would have suddenly caused dinosaurs to go extinct.
Go extinct because their babies hatched as all males or all females? No. This theory—which is based on the fact that the sex of baby alligators and crocodiles is determined by outside temperature—can't be easily tested. But it cannot explain why other animals that rely on temperature-dependent sex determination survived.
Want to join the conversation?
- I think it was climate change, since mammals have hair or fur, and birds have feathers, they were able to survive the cold tempurature that came with the Ice age. Even if dinosaurs went extincnt before that, it might have been the gradual change, and the animals that didn't adapt, died out.(4 votes)
- Unfortunately, just the climate simply growing colder doesn't explain why many cold-blooded (so less able to cope with cold temperatures) animals survived, like crocodiles, and why many warm-blooded animals didn't, including birdlike dinosaurs, an entire branch of primitive true birds and about 90% of marsupial mammals. Climate change might well have been involved, but it was almost certainly more complicated than just one factor.(7 votes)
- DIdn't the dinosaurs have feathers(4 votes)
- I think there would be situations like this - a asteroid fall in one of the oceans - waves - tsunami - half dinos dead - volcanic eruptions - tornados - no sun light - no photosynthesis - no food for herbivores - herbivores starved - meat eaters found dead - ate them - no herbivores - meat eaters died . The end of the dinosaurs!(3 votes)
- Did dinosaurs get too big to survive?(2 votes)
- How can you tell the most evolved mammal like reptile(A reptile that looks like a mammal in some ways) from the first mammals?(1 vote)