Question

Briefly describe the evidence suggesting that a 10-km asteroid or comet hit Earth at the time of the dinosaur extinction.

a) Fossils of large dinosaurs show signs of burn marks.
b) A layer of iridium-rich clay is found at the K-T boundary.
c) The presence of volcanic activity indicates an impact.
d) Dinosaur footprints have been found near impact sites.

Answer 1

The evidence suggesting a 10-km asteroid or comet hit Earth at the time of the dinosaur extinction includes burn marks on dinosaur fossils, a layer of iridium-rich clay at the K-T boundary, and the discovery of an impact crater.

Step-by-step explanation:

The evidence suggesting that a 10-km asteroid or comet hit Earth at the time of the dinosaur extinction includes:

1. Fossils of large dinosaurs show signs of burn marks. This indicates intense heat from a high-energy event, consistent with an asteroid impact.
2. A layer of iridium-rich clay is found at the K-T boundary. Iridium is rare on Earth's surface but abundant in asteroids and comets. Its presence suggests an extraterrestrial source, such as a large impact.
3. The report of an appropriately aged and sized impact crater. A crater matching the size and age of the impact event has been discovered in the Yucatán Peninsula, providing further support for the asteroid impact hypothesis.