The Chicxulub Impactor: Comet or Asteroid?

TL;DR

This paper critiques a recent claim that a comet caused the dinosaur extinction, emphasizing the need for extreme assumptions and highlighting evidence favoring an asteroid impact instead.

Contribution

It provides a critical analysis of the evidence and assumptions used to argue for a comet impact, reaffirming the asteroid hypothesis for the Chicxulub impact.

Findings

Critiques the assumptions about comet fragmentation

Highlights the iridium layer evidence favoring an asteroid

Questions the conflation of different carbonaceous chondrites

Abstract

A recent paper by Siraj & Loeb (2021) entitled "Breakup of a long-period comet as the origin of the dinosaur extinction" attempts to revive the perennial debate about what type of body hit the Earth 66 million years ago, triggering the end-Cretaceous extinction. Here we critique the paper and assess the evidence it presents. To consider a comet more likely than an asteroid requires extreme assumptions about how comets fragment, conflation of carbonaceous chondrites with specific types of carbonaceous chondrites, and a blind eye to the evidence of the iridium layer.