The iridium layer, which has been dated to approximately 65 million years ago, is often associated with the Cretaceous-Paleogene (K-Pg) boundary, marking the mass extinction event that led to the demise of the dinosaurs and many other species. Given that the fossilized organism is found in the layer immediately below the iridium layer, the scientist can infer that the organism lived in the Late Cretaceous period.
A scientist is excavating fossils from a site in the Mississippi Valley. She observes that there is a thin layer of the rare metal iridium in a sample of well-preserved rock. Radiometric dating techniques show that this layer was created 65 million years ago.
The scientist continues her investigation and uncovers a fossilized organism from a layer of rock immediately below the layer of iridium. Assuming these rock layers have not been disturbed, the scientist can infer that the organism lived in the ___
period.
1 answer