Lab2_The Pangea Puzzle

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Texas A&M University *

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207

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Geology

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Apr 3, 2024

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docx

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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 geologic 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/navig HYPERLINK "https://paleobiodb.org/navigator/"a HYPERLINK "https://paleobiodb.org/navigator/"tor/ The Navigator consists of three parts: • 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. • 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. • 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 • Enter Lystrosaurus in the search field and click enter. • 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. • Describe the locations of the fossil finds in terms of the continents and/or countries in which the fossil were found. (1 pt) It looks like they were found in Asia. There are some in central Asia, some in Western Asia, and some in Southern Asia. They are in Western Russia, China, and India. They are also in Southern Africa, specifically South Africa, an even a few on Antarctica. • 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. • Based on this matching, during which geologic period did the majority of the Lystrosaurus found live? (1 pt) They mainly lived in the early triassic period. • 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. • Describe how the position of the fossil finds changed. Are they now closer together or further apart? (1 pt) They are much closer together. There are still some far away, but the biggest clusters are all much closer. • Save a copy of your map for Lystrosaurus and paste it on the fifth page of this lab (1 pts) . 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 • Enter Mesosaurus in the search field and click enter. (Be sure to clear out the information about Lystrosaurus .) • Look at the distribution for these fossils. • Describe the locations of the fossil finds in terms of the continents and/or countries in which the fossil were found. (1 pt) They are in Southern Africa, in South Africa and Namibia. They are also in South America, in Brazil. • In what ways is the distribution of Mesosaurus different from Lystrosaurus ? (1 pt) They are all closer to coastlines. They are both in Africa, but the Mesosaurus is in South America, while the lystrosaurus is not. The lystrosaurus is in Asia, while the mesosaurus is not.
• Given the different ecologies of Mesosaurus and Lystrosaurus, provide a well-reasoned explanation for why their distributions are different. (1 pt) I think that it would make sense for the mesosaurus to be in South America, while the lystrosaur is not because the mesosoaur was an aquatic animal. It was probably able to swim to that continent while the lystrosaur was not. They chose instead to move through Asia on land, because they are mammals that live on land. • How do you think this animal might have gotten distributed in this pattern? (1 pt) I think they could have swam from what is now Africa to what is now South America when the continents were much closer together. • Click on the time period on the geological time scale that represents when the majority of Mesosaurus fossils were found. • Describe how the position of the fossil finds changed. Are they now closer together or further apart? (1 pt) They are now much closer together. • Save a copy of your map for Mesosaurus and paste it on the fifth page of this lab (1 pts) . • Glossopteris is a genus of seed ferns, and extinct group of plants that lived in Permian period. Image from OSU QM 270-16-B, Orton Geology Museum, Ohio State University, Columbus, Ohio, USA CC BY-SA 3.0   via Wikimedia Commons . • Enter Glossopteris in the search field and click enter. (Be sure to clear out the information about Lystrosaurus .) • Look at the distribution for these fossils. • Describe the locations of the fossil finds in terms of the continents and/or countries in which the fossil were found. (1 pt) They are scattered across Asia, South America, Southern Africa, Australia, and Antarctica. • In what ways is the distribution of Glossopteris different from Lystrosaurus ? (1 pt) These covered a lot more ground than the Lystrosaurus. They are on almost every continent. • Provide a well-reasoned explanation for there are so many more fossil occurrences of Glossopteris than Lystrosaurus . (1 pt) I think a Lystrosaurus would've been largely dependent on many environmental factors, like food, to reproduce. Because this is a plant, I think it was able to distribute its seed much more efficiently,leading to a much larger distribution across all of these continents. Back then, the continents were so close together, it must have been easy to distribute a large amount of seeds across lots of land. • Using the data on the distribution of these three organisms from the Permian and Triassic as evidence, provide a well-reasoned argument for the claim that continents that are distant today
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