Astronomers: A comet fragment, not an asteroid, killed off the dinosaurs
Jupiter's gravity pushed comet toward Sun; comet was ripped apart by tidal forces.
Jennifer Ouellette, ArsTechnica, February 15, 2021
https://arstechnica.com/science/2021/02/astronomers-a-comet-fragment-not-an-asteroid-killed-off-the-dinosaurs/
The open access paper is:
Siraj, A. and Loeb, A., Breakup of a Long-Period Comet
as the Origin of the Dinosaur Extinction.
Scientific Reports volume 11, Article number: 3803 (2021)
https://www.nature.com/articles/s41598-021-8232