Building Bridges

Learning Target• I can use real data to construct links between the processes of

plate tectonics and the records of biological evolution.

Process & Procedure• 1. What are some similarities and differences in the 2 maps?

Process & Procedure• 3. The Caribbean region has hosted a coral reef ecosystem for

at least 20-30 Myr. Where else might the reef ecosystem be found during that time?

• Would organisms in the ecosystem have been isolated in the Caribbean during that time period?

Process & Procedure• 4. Figure 13.21 shows rock layers with fossil finds at 6 sites in

North and South America. Are older rocks found at a deeper or shallower position?

Process & Procedure• Which sites have the most mammals? Which have the

fewest?

Process & Procedure• Animals or plants that are restricted to a specific region are

called endemic.• How can you tell whether an animal is endemic to a continent

based on the geologic record?• Endemic animals would only be found in a certain region. You

could group the sites by continent, and look at a certain time period to find animals that are only found in South America.

• To find the endemics in South America, you should look at Columbia and Argentina, and search the bottom parts of the strata.

Process & Procedure #6cEndemic to South America Endemic to North America ??

Armadillo Cat

Porcupine Camel

Glyptodont Dog

Opossum horse

Capybara

sloth

Process & Procedure• 6d. Why does the question say “might” be endemic to North

America?• Look at the maps. We can see that 10-12 Mya, South America

was isolated. Do the maps tell if North America is isolated?

Process & Procedure• 7a. When do South American animals arrive in North

America?

• 7b. How can you explain the arrival of South American endemics in North America?

Glyptodonts and sloth arrived in Mexico by 3.5 Mya. Capybara arrived in Mexico by 4 Mya, and Arizona by 2.5 Mya.

The animals probably migrated via the land bridge (Central Americal), which had formed around this time. Before this time there was no land bridge so animals could not migrate from SA to NA.

Process & Procedure• 7a. When do South American animals arrive in North

America?

• 7b. How can you explain the arrival of South American endemics in North America?

NA animals are first recorded in Columbia and Argentina about 2.5 Mya.

The animals probably migrated via the land bridge (Central Americal), which had formed around this time. Before this time there was no land bridge so animals could not migrate from NA to SA. Animals were moving in both directions.

Process & Procedure• 8. Examine the geologic record of the rhinoceros family in Fig.

13.21. What is the time period of when they are found? What inferences can you make about the history of the rhinoceros family?

The rhino can only be found in North America. It appears in Arizona at 10 Mya, and then in all 4 NA locations until 5Mya. It no longer appears in North America after 5Mya. This signifies that the rhinos became extinct in North America about 5 Mya.

Process & Procedure• 9. Based on Fig 13,21, make some inferences about the

mammoth family. What is the earliest evidence of its appearance in the fossil record?

Mammoths appear in North America at 2 Mya. They do not appear in South America at all. This signifies that the mammoth migrated to North America from elsewhere (possibly the Bering land bridge that connected North America and Siberia).

Process & Procedure• 10a. What do you think is the land bridge between North and

South America?

• 10b. When do you think the land bridge formed? What is your evidence?

It is the region of Central America (Costa Rica and Panama).

Fossil evidence shows that animals were migrating between SA and NA about 3 Mya. Therefore, there must have been a continuous land bridge by that time.

Process & Procedure• 10c. Which animals did or did not use a land bridge?

• 10d. Which tectonic plates were involved in the land bridge?

Each animal in the fossil record except the rhino used the land bridge. Each animal that was endemic to SA is shown to have appeared in NA at a later time. The rhino could not ave used the land bridge because it was extinct in NA before the land bridge appeared..

.The Central American land bridge resides in a zone of convergence between North and South America. Looking at the tectonic plate boundaries, it is a zone of convergence between the Cocos plate and the Caribbean plate.

Process & Procedure• 10d. Which tectonic plates were involved in the land bridge?

.The Central American land bridge resides in a zone of convergence between North and South America. Looking at the tectonic plate boundaries, it is a zone of convergence between the Cocos plate and the Caribbean plate.

Process & Procedure• 10e. Which of the 3 main types of tectonic settings best

applies to the Central American land bridge?

• 10f. What process resulted in the Central American land bridge?

It would have to be a convergent zone because it is created by uplift, which is only found in convergent zones.

.It was created by uplift within a zone of collision. This is consistent with the type of boundary between the Cocos and Caribbean plates at that location.