Lab2_The Pangea Puzzle Completed
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Texas A&M University *
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207
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Geology
Date
Apr 3, 2024
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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)
Lystrosaurus fossils were found in South Africa, East India (Asansol), Northern China, and Western 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)
Majority of Lystrosaurus fossils were estimated to have lived in the Early Triassic (or simply 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)
The fossils are closer together where they were previously continents apart. 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)
Mesosaurus fossils were found in South Brazil, Namibia, and South Africa.
b.
In what ways is the distribution of Mesosaurus
different from Lystrosaurus
? (1 pt)
The Mesosaurus fossils were separated by an ocean – and on different continents - where the Lystrosaurus fossils were found on different continents, but farther apart (they were more sporadically found) c.
Given the different ecologies of Mesosaurus and
Lystrosaurus, provide a well-reasoned explanation for why their distributions are different. (1 pt)
Both of these animals were found in similar and different environments. This means that the Lystrosaurus and the Mesosaurus eventually, over time, adapted to live in different environments. This would explain why both fossils were found in present-
day South Africa while the Mesosaurus fossils were found in current day Brazil and other Lystrosaurus fossils were found in Northern China and Russia.
d.
How do you think this animal might have gotten distributed in this pattern? (1 pt)
The movement of land masses would describe this. When and where we found the fossils (present day) looks drastically different to when the dinosaurs were actually living. 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)
When the Mesosaurus fossils were most often dated together, they were closer 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.
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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)
Glossopteris fossils are found in South American (Southern), Africa (Southern), Antarctica, India, Turkey, Oman, China, and Australia, g.
In what ways is the distribution of Glossopteris
different from Lystrosaurus
? (1 pt)
Glossopteris fossils are found more sporadically and dated to have lived a longer span of time. Lystrosaurus fossils were found in four primary locations: South Africa, some of China, Asansol (India) and some of Russia. While they do share locations, Glossopteris fossils have a more expansive reach. h.
Provide a well-reasoned explanation for there are so many more fossil occurrences of Glossopteris than Lystrosaurus
. (1 pt)
There are more Glossopteris occurrences because they lived for a longer period of time. There are fossils dated from the Pennsylvanian period (or dated to be somewhere in the Paleozoic period) through the Ladinian period (or dated to be somewhere in the Triassic period).
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)
Glossopteris, Lystrosaurus, and Mesosaurus fossils were found primarily on coastlines of several different continents and countries. This doesn’t make sense, in terms of distribution and differences in ecosystems, to when these animals were dated to have lived. It would make more sense if these land masses were more whole when these animals were living. The coastlines would match up, like a puzzle piece, and provide us with one or two more distinct areas, with similar environments, these animals would have lived in.
Paste your maps of Lystrosaurus
, Mesosaurus, and Glossopteris here.
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)
Tyrannosaurs and Hadrosaurus were found primarily in North America with a few findings in Asia. Spinosaurus and Carcharodontosaurus were found primarily in Africa with a few findings in South America.
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)
These genera were (for the most part) grouped together onto a single continent. This is because, by the Cretaceous period, the continents were mostly separated and it would be unlikely to find the same genera on all continents of the world, especially if there are oceans separating the species. 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 findings in this lab support the above claim. Part 3 supports the claim that a genus is typically found in a more specific location rather than on all parts of the world. With this in mind, knowing that the genera found in the Paleozoic period was located on several different continents shorelines (current day), it would make more sense that the continents were originally closer together if not connected. Genus
N. America
S. America
Asia
Europe
Africa
Australia
Antarctica
Tyrannosaurs Hadrosaurus
Spinosaurus
Carcharodontosaurus
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Paste your Cretaceous Dinosaur maps here