Directions for teachers: Ask students to read the online Science News article “The Age of Dinosaurs may have ended in springtime,” which describes how scientists used fossilized fish to determine what season it was when an asteroid wiped out nonavian dinosaurs, and answer the following questions. A version of the article, “Dinosaur killer may have hit in spring,” appears in the March 26, 2022 issue of Science News.

1. A claim is an assertion of something as a fact. What is one scientific claim made by scientists in the article?

The asteroid that killed the nonavian dinosaurs happened in Northern Hemisphere springtime.

2. Claims often serve as answers to questions. What scientific question might the scientists’ claim attempt to answer?

When exactly did the asteroid that killed the dinosaurs strike Earth?

3. Evidence is the scientific data that are given to support a claim. What information do the scientists give as evidence?

Scientists examined the jawbones and fin bones of fish that died in the impact’s aftermath. Solidified globs of molten and vaporized rock in the animals’ gills indicate the fish were alive when the asteroid hit. The bones show signs that at the time of death, the fish were in the middle of a rapid growth cycle.

4. Reasoning is the explanation of why the evidence supports the claim. What reasoning is given by the scientists?

For these fish, previous rapid growth cycles peaked around summertime. Since the fish were in the middle of a growth cycle when they died, that points to springtime as the season of the impact.

5. Who did the research? What is their expertise?

Melanie During and her colleagues did the research. During is a vertebrate paleontologist at Uppsala University in Sweden. She studies ancient animals with backbones.

6. Who else is quoted in the article? What do they say about the findings and how does that contribute to your understanding?

Stephen Brusatte is quoted in the article. He also is a vertebrate paleontologist but was not involved in the research. In his opinion, the evidence that During’s team presents provides strong scientific support for the team’s claim.