If you enjoy the broad sweeping claims of geologist at Berkeley, which turned him into a Rock Star, the dinosaurs were all killed off by a six mile wide asteroid impacting in Mexico 65 million years ago. Its a popular idea. Everybody knows about it. The author leveraged that into getting laid, good dinner parties, the best booze, book deals, and the talk show circuit. The problem with his hypothesis is it probably isn't right. An asteroid (or comet) did hit at Chicxulub Mexico, near the north side of the Yucatan Penninsula, around 65 million years ago. That's fact and not disputed. There's a fantastic oil reservoir, shocked quartz from the impact, all the usual impact evidence and a way to date it.
The problem with the impact hypothesis is the impact didn't kill a number of fragile species still around today, stuff we know is fragile because lots of things kill them. Things like sea turtles, crocodiles, birds, freshwater and ocean fish, the trees and plants. If the impact had happened as claimed, at the height of dinosaur superiority, there would be entire fields of dead dinosaurs covered in inches of iridium rich ash and clay from the impact. There isn't. Not even one dinosaur fossil covered in that ash. The odds really favor it if they were going strong and died all together.
Of course, if something else killed them first, like say some old variant of bird flu spread when North and South America joined together, something not carried by pteranodons but eventually mutates and kills them too, that could have killed off all the dinos 2500 years before the asteroid (or comet) hit. That's the closest we've come dating a dino to the impact, to the clay layer. 2500 years. That's all of human civilization with Democracy, if you start with the Athenians. The asteroid, according to the evidence, hit a planet where the dinos were already dead, and wasn't bad enough to kill off the birds and fish etc. Even with a 6 mile wide rock, and the nuclear winter, the birds survived, as did the sea turtles who are on the verge of extinction today we consider so cute with their babies hatching and trying to reach the sea down in the Caribbean or Africa or Indonesia. We still have freshwater and ocean fish. So the big rock killing them all? Its obviously wrong.
Another hypothesis suggests the Deccan Traps in India. They are major volcanic eruptions that went on through 10K years. They could have killed them off, but that also leaves the turtles, crocs and fish and birds alone without explanation.
I still favor the disease option. They're different enough animals it might not have hit them. I don't understand how it killed the Cretaceous nautiloids, called Ammonites, as they're sea creatures that should have been insulated from all this, but they died with the dinos for some reason, along with the swimming dinos but not the reefs. And not the crocodiles. Not the fish. Not the birds. But killed the provably warm blooded dinos in Alaska, which was turned 90 degrees but still up there and still in darkness several months a year, with snow. They had to be warm blooded or they'd be unable to move and die out. So why would they die from an Impact Winter? They wouldn't. It had to be something else.
A few paleontologists point this out, because paleontologists study ancient animals rather than more general rocks and environments. They don't get as much airplay with the media because big decisive science sells newspapers and advertising. It doesn't have to be right. If its wrong, its even better because then its a scandal and that sells even more. This is a great reason to dislike the media, btw. Truth is the furthest thing from profit. Paleontologists don't get much traction outside of real science on this issue because there are too many idiots deciding whom to fund, who to make documentaries about, and the guy with the asteroid killing the dinosaurs?
That dovetails nicely with judeo-xtian-muslim apocalypse religion and that's easy to sell to funding agencies. We need more religions that sell the idea of continuation rather than annihilation. Probably won't be as popular, since localized apocalyptic events (earthquake, fire, hurricane, tornado) happen often enough, but that could be worked in, pointing out that life goes on. Not for those who died in the event, but for everybody else there's cleanup and rebuilding. The Dinosaurs did die out, but I think it happened before the rock hit Mexico. All the evidence supports that. What exactly killed them isn't known.
It would be cool to find out the exact virus that did it. Find one in a fossil and code it up to study it. And before you worry... we are descended from the animals immune to it, as are all the other animals. It's harmless to us. It's probably loose, possibly already known to science, and still floating around out there in Brazil and the Congo, with no symptoms. There are diseases like that. If a dinosaur were recoded and brought to life? It would probably die shortly after birth from this just being breathed on by someone who owns a pet bird and is an asymptomatic carrier of the disease. That actually happens with bird owners, btw. Rather anticlimactic turn for a Jurassic Park attempt.
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