Question

1. approximately how long ago have the dinosaurs become extinct? 10. what is the evidence for the mass extinction of the dinosaurs?

Explanation:

For question 9, geological evidence and radiometric dating techniques are used to estimate the time of dinosaur extinction which is about 66 million years ago. For question 10, evidence for the mass - extinction of dinosaurs includes the iridium - rich layer in the geological record indicating a large - scale extraterrestrial impact, and the sudden disappearance of dinosaur fossils in the rock strata.

Answer:

1. Approximately 66 million years ago.
2. Iridium - rich layer in geological record, sudden disappearance of dinosaur fossils in rock strata.