Lab2_The Pangea Puzzle (1)

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Texas A&M University *

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Course

207

Subject

Geology

Date

Apr 3, 2024

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pdf

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7

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The Pangea Puzzle Introduction One of the most fundamental questions we can ask in geology is how the continents that we see today got to be in their current configurations. Data on the distributions of organisms in the fossil record make it possible to identify where they lived in the past, and that data can be used to help identify past continental positions. To do this, paleontologists track the occurrence of fossil organisms, in other words where a species occurs in space (geographically) and when a species occurs in time (stratigraphically). The Paleobiology Database (PBDB, https://paleobiodb.org/navigator/ ) is a huge online database that seeks to catalogue all fossil occurrences, across all geolog ic time, and across the whole tree of life. It’s the standard tool used by paleobiologists to track where fossil organisms lived and when. Delving into the Database Open the PBDB Navigator and spend some time getting comfortable with how it works: https://paleobiodb.org/navigator/ The Navigator consists of three parts: 1. Map (CENTER) showing continents with dots representing fossil occurrences. The color of these dots represents their geologic age. If you click on the dots, you can see all of the information on each site and the fossil species that occur there. 2. Geologic time scale (BOTTOM) showing the major eras, periods, and stages. If you click on the timescale, the map will show you the location of all fossil occurrences from that time interval. 3. Tool bar (LEFT) showing the tools you can use to explore the database. These include: zoom in/out on the map reconstructs plate tectonic configurations for time interval you are exploring narrow down which taxonomic group is plotted on map create a diversity curve for the occurrences currently plotted on map download the data (lat/long, geologic age, etc.) for the occurrences plotted on map Need help? Here’s a YouTube video to help you get started: https://www.youtube.com/watch?v=db2He3p-Jco
Goal: Use fossil distributions to test the hypothesis that the modern continents were joined in Pangaea during the Late Paleozoic but largely separated in Mesozoic. Step 1: Construct maps of fossil distributions Lystrosaurus is not a dinosaur. It is a genus of synapsid, and thus more closely related to mammals than to dinosaurs, that lived in the Late Permian to early Triassic. Reconstruction of Lystrosaurus murrayi. Image by Dmitry Bogdanov CC BY-SA 3.0 via Wikimedia Commons 1. Enter Lystrosaurus in the search field and click enter. 2. The dots on the map show where in the modern world paleontologists have discovered fossils of Lystrosaurus . At this point, stop and consider your map. a. Describe the locations of the fossil finds in terms of the continents and/or countries in which the fossil were found. (1 pt) 3. The color of the dots on the map match those of the geologic time scale below, indicating the age of the fossils. You may need to zoom in a bit to get the dots to change to a specific color. a. Based on this matching, during which geologic period did the majority of the Lystrosaurus found live? (1 pt) 4. Now, reconstruct the map at that time period by clicking on the name of the time period in the geologic time scale followed by the tool bar icon showing the continents on the left. Note that the map changes, moving the continents to their positions during the time period that you clicked. a. Describe how the position of the fossil finds changed. Are they now closer together or further apart? (1 pt) b. Save a copy of your map for Lystrosaurus and paste it on the fifth page of this lab (1 pts) . Fossils were found in South Africa, China, India, and Russia. Majority of Lystrosaurus found lived during the Early Triassic period. The fossil finds are now closer together because all the continents are pushed together making on large land mass.
Repeat this process for Mesosaurus and Glossopteris . Mesosaurus is also not a dinosaur. It is an extinct genus of aquatic reptile from the early Permian. Reconstruction of Mesosaurus . Image by Nobu Tamura CC BY-SA 3.0 via Wikimedia Commons 5. Enter Mesosaurus in the search field and click enter. (Be sure to clear out the information about Lystrosaurus .) 6. Look at the distribution for these fossils. a. Describe the locations of the fossil finds in terms of the continents and/or countries in which the fossil were found. (1 pt) b. In what ways is the distribution of Mesosaurus different from Lystrosaurus ? (1 pt) c. Given the different ecologies of Mesosaurus and Lystrosaurus, provide a well-reasoned explanation for why their distributions are different. (1 pt) d. How do you think this animal might have gotten distributed in this pattern? (1 pt) 7. Click on the time period on the geological time scale that represents when the majority of Mesosaurus fossils were found. e. Describe how the position of the fossil finds changed. Are they now closer together or further apart? (1 pt) 8. Save a copy of your map for Mesosaurus and paste it on the fifth page of this lab (1 pts) . The fossils were found in South Africa, Namibia, and Brazil. The distribution is different because there are more fossil finds grouped together than the Lystrosaurus and they are also leaning more towards the America's rather than Europe The Mesosaurus is an aquatic reptile, therefore, it needs to be closer to water and should be in coastal regions. Whereas a Lystrosaurus is a mammal and would do better in a land-based environment. Their fossils were probably originally in the water so over time it can be inferred that the water pushed out their remains. This would've distributed them along the coasts of the respective continents just like the map shows. They are much closer together now that there isn't a large body of water separating them. It is almost as if they were all in a group before they got separated.
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