What really caused the dinosaurs to go extinct? I'm bored and want to know the answer.

The Cretaceous-Tertiary extinction event, or the K-T event, is the name given to the die-off of the dinosaurs and other species that took place some 65.5 million years ago. For many years, paleontologists believed this event was caused by climate and geological changes that interrupted the dinosaurs' food supply

Explanation:

google has answers.

What is clear is that a massive die-off took place around 66 million years ago. It is visible in the layers of rock that mark the boundary between the Cretaceous and Paleogene periods. Fossils that were once abundant no longer appear in rocks after that time. Studies of fossils found (or not found) across the boundary between these two periods — abbreviated the K-Pg boundary — show that some three out of every four plant and animal species went extinct at about the same time. This included everything from the ferocious Tyrannosaurus rex to microscopic plankton.

(Though, like, do they REALLY know it was 66 million years ago?)

Iridium is rare in Earth’s crust but abundant in asteroids and other space rocks. The finding marked the first hard evidence for a killer-asteroid impact. But without a crater, the hypothesis couldn’t be confirmed.

It circled the coastal Mexican town of Chicxulub Puerto. (The crater actually had been discovered in the late 1970s by oil company scientists. They had used variations in Earth’s gravity to visualize the crater’s 180-kilometer- [110-mile-] wide outline. Word of that find, however, did not reach crater hunters for years.) Based in part on the gaping size of the depression, scientists estimated the size of the impact. They figured it must have released 10 billion times as much energy as the nuclear bomb dropped on Hiroshima, Japan, in 1945.

That's big.

Evidence of the supersized tsunami generated by the Chicxulub impact had previously been found only around the Gulf of Mexico. It had never been seen this far north or so far inland. But the symptoms of tsunami devastation were clear, DePalma says. The rushing water dumped sediment onto the landscape. The debris originated from the nearby Western Interior Seaway. This body of water once cut across North America from Texas to the Arctic Ocean.

Evidence of the chilling darkness is in the rock record. Local sea surface temperatures modified lipid (fat) molecules in the membranes of ancient microbes. The fossilized remains of those lipids provide a temperature record, reports Johan Vellekoop. He is a geologist at the University of Leuven in Belgium. Fossilized lipids in what is now New Jersey suggest that temperatures there plummeted 3 degrees C (about 5 degrees F) following the impact. Vellekoop and colleagues shared their estimates in the June 2016 Geology.

Over the years, scientists have blamed many suspects for this catastrophic die-out. Some have suggested global plagues struck. Or maybe a supernova fried the planet. In 1980, a team of researchers including father-son duo Luis and Walter Alvarez reported discovering lots of iridium in places worldwide. That element appeared along the K-Pg boundary.

Will we EVER know for sure?

the most speciallized is b. grizzly bear