Discrepant Activity for - The Nature of Science Dinosaur Extinction hypotheses or theory

Preparation

Create two data sheets. One with evidence of volcano and the other for evidence of asteriod.

Evidence for the Volcanism Hypothesis - source

• Immense lava flows covered nearly 200,000 square miles of the Deccan region of India, reaching depths of more than 6,500 feet in places. - This lave flow provides evidence of volcanic activity for at least 500,000 years leading up to the extinction of the dinosaurs.
• The metal iridium, similar to platinum, is a very rare metal on the Earth's surface, but is common in asteroids and in molten rock deep within the planet. - Some scientists think the presence of high concentrations of iridium at the geological layer associated with the dinosaur extinction could be the result of extremely large-scale volcanic activity.
• Shocked quartz show a distinct pattern of fractures caused by high-energy impacts or explosions. Geologists acknowledge a comet or asteroid impact would cause these fractures, and some scientists conclude they could also be the result of volcanic eruptions.
• A gradual decline in the number of dinosaur species found in the fossil record would need an equally gradual cause for their extinction. Similarly, a sudden end to the dinosaurs means a catastrophic cause. - Depending on location and interpretation, conclusions from the fossil record can be different. - A gradual decline in the number of dinosaur species seems to support a gradual process - like climate change caused by global volcanism.

Evidence for the Asteroid Impact Hypothesis - source

• A 150-kilometer-wide impact crater lies just off the Yucatan peninsula. Scientists calculate it was blasted into Earth by a 10-kilometer-wide asteroid or comet traveling 30 kilometers per second - 150 times faster than a jet airliner. Scientists concluded the impact occurred 65 million years ago. The date corresponds perfectly to the date of the dinosaur extinction.
• The metal iridium, similar to platinum, is a very rare metal on the Earth's surface, but is common in asteroids and in molten rock deep within the planet. - Scientists discovered levels of iridium 30 times greater than average in the Cretaceous/Tertiary (KT) boundary, the layer of sedimentary rock laid down at the time of the dinosaur extinction.
• Pieces of once-molten rock, called impact ejecta, are evidence of an explosion powerful enough to instantly melt bedrock and propel it more than a hundred miles from its origin. - Ranging in size from large chunks to tiny beads, impact ejecta are common at or near the retaceous/Tertiary (KT) boundary, the geological layer that defines the dinosaur extinction.
• Shocked quartz show a distinct pattern of fractures caused by high-energy impacts or explosions. - Scientists maintain the fracture pattern in these quartz crystals could only have been caused by a massive asteroid or comet impact. The pattern is prevalent in quartz found at or near the Cretaceous/Tertiary (KT) boundary, the geological layer deposited at the time of the extinction.
• A gradual decline in the number of dinosaur species found in the fossil record would need an equally gradual cause for their extinction. Similarly, a sudden end to the dinosaurs means a catastrophic cause. - Depending on location and interpretation, conclusions from the fossil record can be different. - Some paleontologists see evidence in the fossil record that dinosaurs were doing quite well prior to the end of the Cretaceous -- that they were in no way declining in abundance when the impact occurred.

Procedure

Ask the students to explain if it is possible for two different groups of scientists to use scientific inquiry and arrive at two different conclusions and why they believe it is or is not.

• Share the above information data sheets.
• The first, formulated by one group of scientists, suggests a huge meteorite hit the earth 65 million years ago and led to a series of events that caused the extinction.
• The second, formulated by another group of scientists, suggests that massive volcanic eruptions were responsible for the extinction.
• How are these different conclusions possible if scientists in both groups have access to and use the exact same set of data to derive their conclusions?

Results