Lab2_NicholasH
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Texas A&M University *
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Course
207
Subject
Geology
Date
Apr 3, 2024
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docx
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6
Uploaded by ChiefStraw13148
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)
The majority of the findings were in South Africa while there were some found in India,
north China, Russia, and even 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 these fossils lived in the early Triassic time period around 252-247 MA.
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 definitely a lot closer together while some findings are still quite far from one another. This could possibly be explained by more in-depth geographic information such as climate, biome, or even elevation.
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 fossils were found. (1 pt)
These fossils were found all over South Africa and eastern South America.
b.
In what ways is the distribution of Mesosaurus
different from Lystrosaurus
? (1 pt)
The Mesosaurus seemed to be grouped in one location as the reconstruction of Pangea shows that the two continents were once whole.
c.
Given the different ecologies of Mesosaurus and
Lystrosaurus, provide a well-reasoned explanation for why their distributions are different. (1 pt)
I believe because of the reptile nature of the Mesosaurus it required a certain habitat or biome while the Lystrosaurus was more capable of living in different regions.
d.
How do you think this animal might have gotten distributed in this pattern? (1 pt)
The habitat it was most likely living in must have been where those two continents were separated. This is why they are on the edge of both.
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)
The fossils got very close, and it shows a precise grouping where all the fossils are in the same area.
8.
Save a copy of your map for Mesosaurus
and paste it on the fifth page of this lab (1 pts)
.
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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)
This fossil was found in multiple different continents, including, Asia, South America, Australia, Africa, and Antarctica.
g.
In what ways is the distribution of Glossopteris
different from Lystrosaurus
? (1 pt)
This fossil is found in similar locations but also some new ones that make sense due to its time period. The scattered nature of these fossils shows that it was easily adaptable in multiple biomes.
h.
Provide a well-reasoned explanation for there are so many more fossil occurrences of Glossopteris than Lystrosaurus
. (1 pt)
The most obvious reason behind this is because of the abundance of plants to animals. The chances of
something preserving when there are drastically more is higher. Along with that, Lystrosaurus were smaller creatures and possibly hunted often therefore leaving little to no remains upon death.
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)
When looking at the grouping of the same dinosaur fossils findings you will see that some are found completely across the world. When you try to explain how these fossils were found in these extreme places with no way of getting there you find yourself with only one solution. These continents not only have similar fossils but also match in geology. With all of this evidence and the knowledge of tectonic plate movements, it helps explain why a set of fossils can be found across entire oceans from each other when in reality they were mere miles from each other millions of years ago.
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)
The Tyrannosaurus and Hadrosaurus shared similar locations where their fossils were found mainly in North America while some were even found in Asia. On the other hand, the Spinosaurus and Carcharodontosaur were found exclusively 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)
When you look at the positioning of the continents you see that South America and Africa were very close and somewhat touching allowing for dinosaurs to travel to both sides, but also were far away from North America and Asia making it nearly impossible for dinosaurs to get there. This explains why the Tyrannosaurus and Hadrosaurus were only found in North America and Asia while living in the same time period.
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)
I believe that the continental hypothesis that is “Pangea” is heavily supported as many of the fossils found show signs of migration that would not be possible in today’s world. The separation of our continents by the large oceans makes the process of migration impossible for the creatures millions of years ago. The theory is supported even more by the fact that only some dinosaurs were able to migrate to certain places based on their location as not all continents were touching at their time of existence. All of this points to the fact that while yes the continents were once a super continent there was always movement and change which allowed for migration and spread of organisms to places that seem impossible in today’s world.
Paste your Cretaceous Dinosaur maps here
Genus
N. America
S. America
Asia
Europe
Africa
Australia
Antarctica
Tyrannosaurs Yes
No
Yes
Yes
No
No
No
Hadrosaurus
Yes
No
Yes
No
No
No
No
Spinosaurus
No
Yes
No
No
Yes
No
No
Carcharodontosaurus
No
Yes
No
No
Yes
No
No
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