Answer:
The Chicxulub meteor
Explanation:
The Mesozoic Era includes the Triassic, Jurassic, and Cretaceous Periods, which are pretty synonymous in Paleontology and pop culture (due to a certain film you've probably seen). The final period, the Cretaceous Period, culminated with the impact of the Chicxulub meteor in Mexico and ended the Mesozoic Era.
