Current Events Lesson Plan: March 3-9, 2016
Current Event: Drilling for Answers
In April, a team of scientists will begin drilling into the Chicxulub Crater, an impact crater formed off the Yucatán coast in the Gulf of Mexico by a giant asteroid that helped kill the dinosaurs 65 million years ago. At that time, an asteroid at least 6 miles (10 kilometers) wide slammed into the Yucatán Peninsula, in present-day Mexico. The impact threw up large amounts of gas and dust into the atmosphere. This material would have blotted out the sun for many years. When the dust settled, about half of all species on Earth had gone extinct. All the dinosaurs—except birds, the descendants of dinosaurs—were dead. Only a few kinds of other reptiles survived. The Yucatán asteroid formed a large impact crater, which is now partly on the peninsula and partly in the Gulf of Mexico. Tens of millions of years of plate tectonics and erosion have taken their toll on the crater. But the mark that it left in the rocks should still be clear. The team plans to use a drilling ship to sample rock deep beneath the ocean floor. In drilling into the crater, scientists hope the presence (or lack) of microfossils (tiny preserved remains of ancient organisms) will teach them more about the nature of the asteroid impact and how quickly life returned to the area afterward. The drilling evidence may also better explain how responsible the impact was for the mass extinction of the dinosaurs.
Objective:
For about 160 million years, dinosaurs were the largest and most successful vertebrates on land. Then about 65 million years ago, dinosaurs died out along with many other large animals. Mammals thereafter became the world’s dominant land vertebrates. Scientists have developed many theories to explain dinosaur extinction. The two major theories involve (1) the collision of an asteroid with Earth and (2) large volcanic eruptions in what is now India. The leading theory holds that the mass extinction was caused by the impact of a large asteroid in present-day Mexico. The asteroid impact threw billions of tons of dust and debris into the atmosphere, may have caused huge fires worldwide, and blocked sunlight from reaching the surface of Earth for many years. Because such a catastrophe would have been severe and widespread, plant-eating dinosaurs would have starved to death. As the plant-eaters died, so did the meat-eating dinosaurs that fed on them. The other major theory is that the mass extinction followed volcanic eruptions in present-day India that created huge lava beds and released large volumes of gas, causing rapid climate change. Many scientists think that a combination of causes contributed to the extinction of the dinosaurs. The Behind the Headlines news story and related World Book articles explore the world of dinosaurs and discusses how they may have died out.
Words to know:
Discussion Topics:
1. Ask your students to name some types of dinosaurs. (Students might name the Apatosaurus, Brachiosaurus, Stegosaurus, Triceratops, Tyrannosaurus, Velociraptor.)
2. Ask your student to debate: “If scientists were able to resurrect dinosaurs or other extinct animals by cloning or other methods, should they do it?”
3. Ask your students to use the World Book’s Timelines feature to create a timeline of dinosaur discoveries. (Students may wish to use the Dinosaur discoveries section of the Dinosaur article for help.)