LAB 2 GEOL
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School
Texas A&M University *
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Course
207
Subject
Geology
Date
Feb 20, 2024
Type
Pages
8
Uploaded by KidWaterBuffalo7939
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 countries where a Lystrosaurus fossil was found include Russia, China, India, South Africa, and Antartica. 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 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)
They are, for the most part, closer together than before. The majority of the fossils are concentrated at the lower part of Pangea in the South. There are a few fossils located in the North though.
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 countries where a Mesosaurus fossil was found include Brazil and Uruguay (South America) South Africa and Namibia (Africa). b.
In what ways is the distribution of Mesosaurus
different from Lystrosaurus
? (1 pt)
The Mesosaurus fossils are all from the same time period and aren’t as distributed as the Lystrosaurus fossils are. When viewing the Mesosaurus fossils in the Permian period during Pangea, all of them are very close together, meaning they likely only lived in one habitat. c.
Given the different ecologies of Mesosaurus and
Lystrosaurus, provide a well-reasoned explanation for why their distributions are different. (1 pt) I assume that their distributions are different because the Lystrosaurus can live in several different environments whereas the Mesosaurus can live in just one. Additionally, the constant geological changes occurring during these two separate time periods (Triassic and Permian) contribute to the difference in distribution, because of the state of the continental drift. d.
How do you think this animal might have gotten distributed in this pattern? (1 pt)
The Mesoaurus lived during the Permian period, when Pangea was closer together compared to when the Lystrosaurus existed in the Triassic period. The Mesosaurus was in the southern region of Pangea, and when Pangea began to drift apart, the fossils that were located in this area were separated between South America and Africa.
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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)
They are way closer together during this time because South America and Africa were connected during the Permian period, and then continental drift occurred. 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 Glossopteris fossil is located across the world in the continents of South America, Africa, Asia, Australia, and Antarctica. g.
In what ways is the distribution of Glossopteris
different from Lystrosaurus
? (1 pt)
The Glossopteris is more evenly distributed across the world, including during Pangea. The Glossopteris is a genus of seed ferns, whereas the Lystrosaurus is a mammal – two completely different groups of organisms. h.
Provide a well-reasoned explanation for there are so many more fossil occurrences of Glossopteris than Lystrosaurus
. (1 pt) I believe that weathering, erosion and deposition play a factor in the amount of fossil occurrences. Since the Glossopteris is a seed fern, erosion could have transferred the seeds all around the continent of Pangea and adapted and reproduced, whereas the Lystrosaurus is a living creature that might not have been able to adapt and move as easily as the Glossopteris.
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)
Using the maps provided to look at the different fossils and their locations in real-time vs. the continents in the time period where they’re from, it’s easy to see that continental drift occurred to get them to where they were discovered. All of the fossil types would have to have started closer together for it to make sense since some organisms could not live in or travel on large bodies of water. The only reasonable conclusion is that the continents used to be all connected and drifted apart in what is called continental drift, which explains why the fossils were discovered in places that are now very far from each other. ] Paste your maps of Lystrosaurus
, Mesosaurus, and Glossopteris here. Lystrosaurus Mesosaurus Glossopteris
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 the Hadrosaurus are primarily found in North America and Asia, so they have that in common. The Spinosaurus and Carcharodontosaurus are primarily found in South America and Africa. 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) It makes complete sense how they are distributed, seeing as the Cretaceous period was nearing the end of continental drift and Pangea had already split up. The continents were already formed, and the fossils are in the same location as they are modern day, the continents just moved more with the fossils already on them. 14.
Paste the Cretaceous maps for each genus on the next page of this lab. (2 pts)
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 data collected in the lab directly supports the hypothesis that the modern continents were joined in Pangaea during the Late Paleozoic but separated in the Mesozoic. The Tyrannosaurus, Hadrosaurus, Spinosaurus, and Carcharodontosaurus fossils were all discovered in similar places to where the continents were during the Mesozoic, which proves that the continents had already separated a lot compared to the other fossils we reviewed in the lab. These fossils are found all over the world now but during the Late Paleozoic phase, they were very close together, proving the point that Pangea is very much real. It makes sense for all these fossils to be close together because of the environments that the organisms could live and thrive in, and then when Pangea happened and moved the continents, including the remains of some organisms, it directly adds up to the hypothesis. Genus N. America S. America Asia Europe Africa Australia Antarctica Tyrannosaurs X X X Hadrosaurus X X Spinosaurus X X Carcharodontosaurus X X
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Paste your Cretaceous Dinosaur maps here Tyrannosaurus Hadrosaurus
Spinosaurus Carcharodontosaurus