GEOL 207-Lab2

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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/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) - The fossils were found in South Africa, India, China, and Russia 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) - The majority of the Lystrosaurus found lived during the Triassic geologic time period 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) - The position of the fossil finds split with a majority on the south region and a few up north. They are also closer together than before. b. 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 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) - The fossils were found in South Africa and in South American like Brazil. b. In what ways is the distribution of Mesosaurus different from Lystrosaurus ? (1 pt) - Mesosaurus were less distributed along the map compared to the Lystrosaurus. The Lystrosaurus were discovered in South Africa, Russia, India, and China. Whereas the Mesosaurus just in South America and South Africa. c. Given the different ecologies of Mesosaurus and Lystrosaurus, provide a well-reasoned explanation for why their distributions are different. (1 pt) - Their distributions are different by the different environments they lived in such as aquatic & terrestrial. Also, the different time periods they lived in plays a factor in climate and sea level fluctuations. d. How do you think this animal might have gotten distributed in this pattern? (1 pt) - Before the continents became how we know them today they were part of one big massive continent named Pangea. As Pangea came to break apart due to continental drift this led to the separation between South America and Africa. Both regions which is where we found fossils of Mesosaurus. 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) - South America and Africa were closer together which is why there were fossils found in those regions close together.

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8. 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 . 9. Enter Glossopteris in the search field and click enter. (Be sure to clear out the information about Lystrosaurus .) 10. Look at the distribution for these fossils. f. Describe the locations of the fossil finds in terms of the continents and/or countries in which the fossil were found. (1 pt) - There are fossil finds in South America, Africa, India, Australia, China, and Antarctica g. In what ways is the distribution of Glossopteris different from Lystrosaurus ? (1 pt) - A Glossopteris is a plant whereas the Lystrosaurus is a completely different organism. h. Provide a well-reasoned explanation for there are so many more fossil occurrences of Glossopteris than Lystrosaurus . (1 pt) - There were more Glossopteris than Lystrosaurus because plants reproduce in much larger numbers and cover much more areas like forests. Plants also have a higher preservation potential because they are made out of leaves unlike the Lystrosaurus who is more prone to decay. 11. 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 where once consolidated into a supercontinent. (4 pts) - We find that the continents used to be connected because we find similar species on continents that are now separated. So, this supports the idea of continental drift and the existence of Pangea.

Paste your maps of Lystrosaurus , Mesosaurus, and Glossopteris here.

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Part 3: Dinosauria after Pangea Let’s examine the distribution of some dinosaur genera that originated after the breakup of Pangea. For each genus, individually examine the modern maps check off the modern continents where fossils from each are found using the table. (2 pts) 12. Describe the similarities and differences in the distribution of these genera using names of modern continents or countries. (2 pts) - The Tyrannosaurus and Hadrosaurus are found in North America and Canada and also Asia. The Spinosaurus and Carcharodontosaurus were found in North Afirca. 13. Examine each genus individually on the Cretaceous paleogeographic map. How might the position of the continents explain the distribution of each these genera? (2 pts) - The position of the continents explain the distribution of each because of geographic barriers and also the different suitable habitats for each. 14. Paste the Cretaceous maps for each genus on the next page of this lab. (2 pts) Genus N. America S. America Asia Europe Africa Australia Antarctica Tyrannosaurs ✅ ✅ Hadrosaurus ✅ ✅ Spinosaurus ✅ ✅ Carcharodontosaurus ✅

15. Does the data you collected in the lab support or refute the hypothesis that that the modern continents were joined in Pangaea during the Late Paleozoic but largely separated in Mesozoic? Provide clear evidence and reasoning to support your claim. (5 pts) - The evidence strongly upholds the hypothesis of Pangaea's existence during the late Paleozoic and its seperation in the Mesozoic. This is evident from the distribution of Tyrannosaur and Hadrosaurus fossils, located in North America during the Cretaceous and Late Paleozoic. This indicates that North America was connected to neighboring continents within Pangaea during that time. Additionally, the discovery of Spinosaurus and Carcharodontosaurus fossils in Africa further supports the concept of the supercontinent Pangaea. However, these species are now separated by great distances, a consequence of continental drift. . Paste your Cretaceous Dinosaur maps here

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GEOL 207-Lab2

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