Reply to Desch et al. (2021) on "Breakup of a long-period comet as the origin of the dinosaur extinction"

We reply to criticisms by Desch et al. (2021) regarding our Scientific Reports paper, “Breakup of a long-period comet as the origin of the dinosaur extinction.” The background impact rates of main-belt asteroids and long-period comets have been previously dismissed as being too low to explain the Chicxulub impact event. Our work demonstrates that a fraction of long-period comets are tidally disrupted after passing close to the Sun, each producing a collection of smaller fragments that cross the orbit of Earth. This population greatly increases the impact rate of long-period comets capable of producing Chicxulub, making it consistent with the age of the Chicxulub impact crater. Our results are subject to an uncertainty in the number of fragments produced in the breakup event that leaves the conclusion of a cometary origin being more likely than an asteroidal one unchanged.