The-Day-the-Mesozoic-Died-Student-Worksheet 1

Quiz Published October 2012 Revised July 2014 www.BioInteractive.org Page 1 of 3 Quiz Student Handout To use this document, first read the Instructions and FAQs . This document is made available by the Howard Hughes Medical Institute. Using this document, you agree to use this document in accordance with the Terms of Use . 1. What is the K-T boundary? The K-T boundary is a clay layer that marks the end of a period the Cretaceous period and the Mesozoic era. It marks a mass extinction. 2. If the rocks outside of Gubbio, Italy used to be at the bottom of an ocean, how are they now part of a mountain? They were folded and pushed upwards through tectonic plate movements. 3. Describe the differences scientists saw in the foraminifera found in rock layers above (after) and below (before) the K-T boundary. The foraminifera above the boundary were in abundance but are not in the clay layer at all. 4. Which of the following events are possible sources of high levels of iridium in sediments? Write ‘yes’ or ‘no’ next to each of the four possibilities. There may be more than one ‘yes’ response. An asteroid impact [Yes] Rain Fossilized foraminifera A supernova [Yes] 5. Which of the following pieces of evidence prompted researchers to abandon the hypothesis that a supernova caused the high levels of iridium in the K-T layer? Select one response. [d.] Lack of an isotope of plutonium in the K-T boundary layer 6. Is the following statement true or false? Justify your answer in one or two sentences: “The entire scientific community accepted the asteroid hypothesis after Dr. Alvarez published his paper showing high iridium levels at the K- T boundary.” The statement is false. It was widely accepted by the scientific community that geological events were slow and steady. They treated Alvarez like a novice to the field for entertaining the idea that a catastrophic event could change all life on the planet so quickly.

Quiz www.BioInteractive.org Page 2 of 3 7. Explain why the scientific community was slow to accept the asteroid impact hypothesis. Geologists have understood the changes to the planet to be gradual without major catastrophes. Additionally, a major criticism of the K-T hypothesis was the lack of a crater the right age, type, and size., which Alvarez thought should be 200 kilometers across; unless it was in the ocean, geologists assumed such a large crater would have already been discovered and put on the record. 8. Many different pieces of evidence lead to the formation of the asteroid hypothesis and provided support for the hypothesis, including a. Finding tsunami deposits in the Brazos River Basin, Texas. b. Determining that rocks taken from the Chicxulub crater are the same age as the K-T boundary. c. Discovering gravitational field anomalies on the Yucatan peninsula, from surveys done for oil exploration. d. Finding high levels of iridium in the K-T boundary layer. e. Identifying spherules and shocked quartz in Haiti. f. Finding that an isotope of plutonium is not in the K-T boundary layer. g. Observing differences in foraminifera fossils above and below the K-T boundary layer. i. Which piece of evidence (a-g) lead scientists to conclude that the cause of the K-T boundary layer was extraterrestrial in nature? _______a_____ ii. Which piece of evidence (a-g) lead scientists to dismiss the supernova hypothesis? ____f________ iii. What was the critical piece of evidence (a-g) that supported the hypothesis that an asteroid had struck Earth 66 million years ago? ______b______ 9. How could an asteroid impact kill off so many different species? Select one response. a. Debris from the impact orbiting around the Earth shields sunlight, halting photosynthesis. b. Tsunamis, landslides, and earthquakes caused by the impact killed organisms near the site of impact. c. The impact was so extreme that life at ground zero was vaporized. d. Both A and C are possible. e. A, B and C are possible. 10. Why do we define the K- T event as a mass extinction event? Write ‘yes’ or ‘no’ next to each of the five possibilities. There may be more than one ‘yes’ response. Many species of foraminifera went extinct A large proportion of species went extinct [Yes] The extinction occurred in many habitats around the world [Yes] Tyrannosaur rex went extinct