Final Exam: Cretaceous-Paleogene Mass Extinction

Question 1

T or F: theropod dinosaurs had feathers.

Answer 1

True

Question 2

When did the mass extinction that wiped out the (non-bird) dinosaurs occur?

Answer 2

about 66 million years ago, at the end of the Cretaceous

Question 3

What is the name of the extinction event that ended the Age of Dinosaurs?

Answer 3

Cretaceous-Paleogene (K-Pg) Extinction Event

Question 4

Did the Cretaceous-Paleogene extinction event only kill off dinosaurs, or other animals as well?

Answer 4

Killed off non-bird dinosaurs and many other forms of life.

Question 5

The K-Pg extinction event resulted in the extinction of approximately ____% of all species on Earth at that time

Answer 5

75%

Question 6

What other types of animals were killed off during the K-Pg mass extinction event? (4)

Answer 6

1. Marine reptiles
2. Pterosaurs (flying reptiles)
3. Ammonites (marine mollusks with coiled shells)
4. Many other marine and terrestrial species (numerous other groups of plants and animals such as marine plankton, foraminifera, terrestrial plants, and many other invertebrates and vertebrates)

Question 7

What evidence supports the hypothesis that an asteroid impact caused the extinction? (3 things)

Answer 7

1. A clay layer deposited at the end of the age of dinosaurs contained Iridium, which is a rare element on Earth but common in asteroids
2. Unusual sand grains called “shocked quartz” were found in layers of sediment deposited at the end of the Cretaceous, which was interpreted as a result of an asteroid impact.
3. Tektites found in a layer of sedimentary rock in Haiti from the end of the Cretaceous.

Question 8

What are tektites?

Answer 8

Bits of rock that melted, then cooled into glass

Question 9

Why would such an impact (asteroid impact) cause a mass extinction?

Answer 9

would cause dust to block the sun, killing plants, which would starve animals.

Question 10

Besides asteroid impact sites, what is the only other place humans have ever discovered shocked quartz?

Answer 10

The locations of nuclear explosions

Question 11

a long high sea wave caused by an earthquake, submarine landslide, or other disturbance.

Answer 11

tsunami

Question 12

What do geologists think created the layer of boulders and other gravel found at the end of the Cretaceous period in southern North America?

Answer 12

Giant waves in the ocean produced by the impact

Question 13

How did tsunamis help scientists find the asteroid impact crater?

Answer 13

Impact from the crater triggered tsunamis that radiated outwards from the impact site. Scientists found evidence of these tsunamis in the form of massive sediment deposits far inland from the impact site. By studying these sediment deposits, scientists were able to trace them back to a common point of origin in the Gulf of Mexico, leading them to the Chicxulub crater

Question 14

Where is the asteroid crater from the mass extinction located?

Answer 14

The Yucatan Peninsula of Mexico

Question 15

T or F: The cause of this mass extinction was definitely an asteroid impact.

Answer 15

False, the cause is one of the greatest mysteries in Earth’s history. The asteroid impact is just a hypothesis.