What Caused the Mass Extinction Recorded at the K-T Boundary?
ESU801  The Fossil Record Shows Mass Extinctions

When organisms die, sometimes their remains are preserved as fossils. Determining the ages of these fossils provides a record of the organisms that lived during different periods of Earth's history. Evidence for the K-T mass extinction comes from comparing the fossils found at the end of the Cretaceous period to those found at the beginning of the Tertiary period.

BLM Photo
Fossil ammonite shell. Ammonites are sea animals that became extinct during the K-T extinction.

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More Evidence

Species Affected

1. What biological findings have been reported at the Cretaceous-Tertiary (K-T) boundary?

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