Dinosaurs lived during a time when Earth’s continents were arranged very differently from today. Early in the Mesozoic Era, most land was joined into the supercontinent Pangaea, which let many animals spread across huge connected habitats. As Pangaea broke apart, oceans opened, climates shifted, and dinosaur populations became separated.
This helps explain why similar fossils are found on continents now divided by wide oceans.
Key Facts
- Pangaea existed as a supercontinent during the late Paleozoic and early Mesozoic eras.
- The Mesozoic Era lasted from about 252 million years ago to 66 million years ago.
- Plate speed can be estimated with v = d/t, where v is speed, d is distance, and t is time.
- Continental drift is driven by plate tectonics, including seafloor spreading, subduction, and mantle convection.
- Similar dinosaur fossils on different continents can show that those landmasses were once connected or much closer together.
- Geographic isolation after continental breakup can lead to different evolutionary paths in separated dinosaur populations.
Vocabulary
- Pangaea
- Pangaea was a supercontinent that joined most of Earth’s landmasses into one large land area before it began breaking apart.
- Continental drift
- Continental drift is the slow movement of continents across Earth’s surface over geologic time.
- Plate tectonics
- Plate tectonics is the theory that Earth’s outer shell is divided into moving plates that interact at their boundaries.
- Fossil correlation
- Fossil correlation is the use of similar fossils in different places to match rock layers and reconstruct past environments.
- Vicariance
- Vicariance is the separation of populations by a geographic barrier, such as a new ocean or mountain range, which can affect evolution.
Common Mistakes to Avoid
- Thinking the continents moved quickly enough for dinosaurs to notice is wrong because plate motion is usually only a few centimeters per year.
- Assuming identical fossils on separate continents always mean dinosaurs swam across oceans is wrong because the landmasses may have been connected when those animals lived.
- Treating Pangaea as the setting for all dinosaurs is wrong because Pangaea began breaking apart during the Mesozoic, so later dinosaurs lived on separated continents.
- Using modern maps to judge dinosaur habitats without changing continent positions is wrong because coastlines, climates, and distances were very different in the past.
Practice Questions
- 1 South America and Africa are now about 2,800 km apart at one matching coastline. If that separation developed over 140 million years, what was the average separation speed in cm/year?
- 2 A dinosaur fossil is dated to 150 million years ago. How many million years before the end of the Mesozoic Era at 66 million years ago did that dinosaur live?
- 3 Two closely related dinosaur species are found in rocks of the same age in South America and Africa. Explain how continental drift could account for both their similarity and their later differences.