Chapter 1: Problem 10

Dinosaurs first appear in the geological record in rocks at 225 Ma and then disappear at 65 Ma. For what proportion (\%) of geological time did dinosaurs exist?

Short Answer

Expert verified

Dinosaurs existed for approximately \(160\) million years, which is about \(\frac{160}{4600}\) or \(3.48 \%\) of geological time.

Step by step solution

Find the duration of dinosaurs' existence

To determine the length of time that dinosaurs existed, subtract the year of their disappearance (65 Ma) from the year of their first appearance (225 Ma): Duration of dinosaurs' existence = \(225 - 65\) Duration of dinosaurs' existence = \(160\) million years.

Calculate the proportion of geological time

To find the proportion of geological time that dinosaurs existed, divide the duration of their existence (160 million years) by the entire history of Earth (4600 million years): Proportion = \(\frac{160}{4600}\)

Convert the proportion to a percentage

Multiply the proportion we found in Step 2 by 100 to convert it into a percentage: Percentage = Proportion × 100 Percentage = \(\frac{160}{4600}\) × 100 Percentage = 0.0348 × 100 Percentage ≈ 3.48 % So, dinosaurs existed for approximately 3.48% of geological time.

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Dinosaurs first appear in the geological record in rocks at 225 Ma and then disappear at 65 Ma. For what proportion (\%) of geological time did dinosaurs exist?

Short Answer

Step by step solution

Find the duration of dinosaurs' existence

Calculate the proportion of geological time

Convert the proportion to a percentage

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