Lab 2

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Texas A&M University *

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207

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Geology

Date

Feb 20, 2024

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docx

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Uploaded by HighnessRaccoonMaster1078

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 fossils were found. (1 pt) Most of the fossils were found in South Africa. There were more fossils found scattered in Russia, China, and India, as well as Antarctica. 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 Lystrosaurus lived in the Early Triassic 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) All of the fossils are now relatively closer together. There are three areas/regions where the fossils were found, the biggest region containing over 20 collections. 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 two main areas. Africa in South Africa and Namibia, and in South America in Brazil and Uruguay. b. In what ways is the distribution of Mesosaurus different from Lystrosaurus ? (1 pt) The distribution of Mesosaurus is different from Lystrosaurus because of the fossils found in South America. Both species were found in Africa, specifically South Africa. However, the Lystrosaurus was present in modern-day Asia. Overall the distribution of the Lystrosaurus is more expansive and spread out. c. Given the different ecologies of Mesosaurus and Lystrosaurus, provide a well-reasoned explanation for why their distributions are different. (1 pt) Due to the different ecologies of the Mesosaurus and Lystrosaurus, the different distributions can be explained by the different ecological adaptations, aquatic and terrestrial. The geological time period also plays a big role due to the changes in continental drift, different sea levels, and climate. d. How do you think this animal might have gotten distributed in this pattern? (1 pt) The Mesosaurus lived during the Permian period when all the continents were a part of the Pangea. Mesosaurus likely lived in shallow waters near Pangea off the modern- day coasts of Africa and South America. As the Pangea changed due to continental drift, the landmasses/continents broke a part. This is why the fossils have been found in two separate regions. 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) In the Permian period, South America and Africa were a part of the same landmass. At this time, the fossils were all close together. 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) The fossils were found in a variety of regions in South America, Africa, Asia, and Australia, and Antarctica. g. In what ways is the distribution of Glossopteris different from Lystrosaurus ? (1 pt) The distribution is different due to the ecological genus, one being a plant and the other being a reptile. Additionally, the species existed in different time periods, Glossopteris lived in the Permian period and the Lystrosaurus lived in the Permian and Triassic periods. h. Provide a well-reasoned explanation for there are so many more fossil occurrences of Glossopteris than Lystrosaurus . (1 pt) There are more fossil occurrences of Glossopteris than Lystrosaurus because of the ways of reproduction. Glossopteris can reproduce in larger numbers and can cover more extensive areas. Unlike the Lytrosaurus, whose distribution depends on the environment and resources like food.

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