Lab 11: Mesozoic A Observations
How This Lab Will Work 1. Open a Word doc or similar on your computer 2. At various points I will ask you to answer a question based on the activities in this lab. 3. I will indicate these points by this symbol:
Please answer these questions in your Word doc.
4. After you have assembled the answers into your Word doc, go to the course Canvas page. 5. On the module for this week there is a link to TurnItIn. 6. Please upload your document using the TurnInIt. 7. That completes the lab assignment. :)
Reminder on Observation Project Please remember that as we go through these, you should be using these fossils to construct your lab observation project, which was detailed last time. Easy to put off, hard to catch up. ;)
Topics Today: 1. Introduction to Mesozoic 2. Phylum Echinodermata: Phymosoma texana 3. Phylum Mollusca: Turritella 4. Phylum Mollusca: Cephalopods: Ammonites 5. Phylum Mollusca: Cephalopods: Belemnites 6. Phylum Mollusca: Bivalvia: Gryphaea 7. Phylum Mollusca: Bivalvia: Exogrya 8. Phylum Mollusca: Bivalvia: Inoceramus 9. Phylum Chordata: Gastrolith 10. Phylum Chordata: Dinosaur footprints (trace fossil) 11. Phylum Chordata: Compsognathus 12. Phylum Chordata: Mosasaurus tooth 13. Phylum Chordata: Mosasaurus 14. Phylum Chordata: Allosaurus
Geology 121 Lab 11: Mesozoic A, page 1 of 8 Introduction to Mesozoic Today we’re going to see examples from the age of the dinosaurs, the Mesozoic (252 - 66 Ma). This time period encompasses the Triassic, Jurassic, and Cretaceous. We can think of the Triassic as a time very much recovering from the devastation of the Great Permian extinction. The major extinction that happened at the end of the Triassic reset the board once again, and the few survivors from the Triassic proliferated and diversified into the Jurassic and Cretaceous.
We will do this lab in two parts, given the large number of specimens we need to examine; this lab will have a few things that aren’t dinosaurs—because, of course, plenty of other critters were evolving during this same time period. Next time we’ll focus more on the major dinosaur examples.
Phylum Echinodermata: Phymosoma texana If you’ve ever been to Texas, and ever cracked open a fossiliferous rock looking for a fossil, you might have seen one of these; they’re pretty common. https://www.nhm.ac.uk/our-science/data/echinoid-directory/taxa/taxon.jsp?id=1437 https://sketchfab.com/3d-models/echinoid-phymosoma-texanum- pri-76726-57316149d2f14a149045e91cb029a384
15. For any echinoderm, how many planes of symmetry do their bodies have? ______
16. Can you see this number of planes of symmetry here? ______
17. Where is the “mouth” of this animal? ______
Please answer these questions in your Word doc.
Phylum Mollusca: Turritella We pick up this form of mollusk in the Jurassic, and they’re still very abundant today. https://sketchfab.com/3d-models/turritella-seriatim- granulata-895f9f383e344e9d990f9de9c37acca0
Geology 121 Lab 11: Mesozoic A, page 2 of 8 18. Looking at the way this shell looks, what do you think this looked like when it was younger? How did it change as it aged? ______
19. What previous organism does this resemble? ______
Please answer these questions in your Word doc.
Phylum Mollusca: Cephalopods: Ammonites https://sketchfab.com/3d-models/cephalopod-cleoniceras-besairiei- a478a7dd64cc43b4a542b1923c45e374
20. Examine the sutures on the polished (brown) area. What do they remind you of? ______https://sketchfab.com/3d-models/cephalopod-perisphinctes-sp- a57e4e04cbf845d89e3d7d331e5d3cce
This is an interesting example of a fossil mold/cast together in the same concretion: https://sketchfab.com/3d-models/cephalopod-gunnarites-sp- pri-61543-6d4851488e1b427a9d1bb970dca6cf2f
Please answer these questions in your Word doc.
Phylum Mollusca: Cephalopods: Belemnites
It might not be immediately obvious what this is: https://sketchfab.com/3d-models/oxyteuthis-brunsvicensis-b2eafdcf8ce4406092ae9e0a5b7a4fbc
However, take a look at an artist’s conception of the animal: https://sketchfab.com/3d-models/belemnite-419-ma-a-66- ma-085ad34e12fb42c185928bbdaaacbeb6
21. How does the first piece fit within the second? ______
Geology 121 Lab 11: Mesozoic A, page 3 of 8 22. Describe the mouth of this organism: ______
Please answer these questions in your Word doc.
Phylum Mollusca: Bivalvia: Gryphaea Gryphea began in the Jurassic and became a common (easily preserved) fossil until their demise in the Eocene. https://sketchfab.com/3d-models/gryphaea-arcuata- birug-50538-8d9ec71de9314cda997e01ad6c572701
23. The nickname of this fossil is “the Devi’s toenails.” Can you explain why? ______
24. How did Gryphaea eat? ______
Please answer these questions in your Word doc.
Phylum Mollusca: Bivalvia: Exogrya Exogyra was a bivalve, though that is not obvious from this. https://sketchfab.com/3d-models/bivalve-exogyra-ponderosa- pri-50396-189acb1a43db40fcb49c4590763f5b90 https://sketchfab.com/3d-models/exogyra-laeviuscula-68a990d8c26c4d589c8f0116f59b8ac1 https://www.digitalatlasofancientlife.org/learn/mollusca/bivalvia/evolutionary-history/
25. What living animal did they most resemble? ______
Please answer these questions in your Word doc.
Geology 121 Lab 11: Mesozoic A, page 4 of 8 Phylum Mollusca: Bivalvia: Inoceramus
Looking again at this page: https://www.digitalatlasofancientlife.org/learn/mollusca/bivalvia/evolutionary-history/ and these https://sketchfab.com/3d-models/bivalve-inoceramus-sp-pri-45554- e6eecc0c2a9b42c592b2789d833fb11e https://sketchfab.com/3d-models/inoceramus-incertus-d9764- c9975e3c58104ddf9084ed963fe2c76e
26. How big were some of the Inoceramids? ______
27. Look closely at the way the shell plates overlap. Sometimes you don’t see the complete fossil, but just a fragment that has that pattern. What would you look for to recognize this from just a small fragment? ______
Please answer these questions in your Word doc.
Phylum Chordata: Gastrolith
Alright, let’s get to the dinosaurs.
Dinosaurs apparently ate rocks and used these to crush food in the stomach. It turns out this acts like a rock tumbler and nicely smooths and polishes the surfaces. When we find a cluster of gastroliths associated with the mid-section of a dinosaur fossil, this gives us a clue about how the functioned. https://sketchfab.com/3d-models/gastrolith-2c48a868eda143098b02182b5599dddf https://ucmp.berkeley.edu/taxa/verts/archosaurs/gastroliths.php https://en.wikipedia.org/wiki/Gastrolith#/media/File:Psittacosaurus_stomach_stones.jpg
28. What other living animals exhibit this same behavior? ______
Geology 121 Lab 11: Mesozoic A, page 5 of 8 29. Why were these necessary? Couldn’t the animals just chew food the way se do?? ______
Please answer these questions in your Word doc.
Phylum Chordata: Dinosaur footprints (trace fossil) https://sketchfab.com/3d-models/raptor-footprint-435f31c15bc54c239d49fe23c0d27045 https://sketchfab.com/3d-models/raptor-footprints-arizona-desert- d7142a2fe4a84e228534e8b336de5228 https://sketchfab.com/3d-models/theropod-dinosaur-footprint-natural- cast-195ecd3e7d8d4bc2be1941dd26a14b9b https://www.nhm.ac.uk/discover/dinosaur-footprints.html
30. How are these different from bird footprints? ______
31. What kind of things can we learn from dinosaur footprints ?
______
Please answer these questions in your Word doc.
Phylum Chordata: Compsognathus
This dinosaur was about the size of a chicken: https://sketchfab.com/3d-models/cast-of-joseph-oberndorfer-compsognathus- fossil-318cd8417bfb40f0ad473f24b1be03f7
32. What are two ways it is anatomically different from a chicken? ______
33. Look especially at the teeth. What might the teeth suggest about how it ate? ______
Here’s how this might have looked in life:
Geology 121 Lab 11: Mesozoic A, page 6 of 8 https://sketchfab.com/3d-models/3drt-dinosaurs-compsognathus- bb1b5ba717b8446db16700f4b0663402
Please answer these questions in your Word doc.
Phylum Chordata: Mosasaur tooth https://sketchfab.com/3d-models/mosasaur-tooth-showing- replacement-83ede84b5a5a434d97975710787cea45 https://sketchfab.com/3d-models/mosasaur-skull- fragments-1da80aee69c94e1792435b5a6cda8964
34. Given this shape, what this an animal that could grind down its food? ______
35. Given this shape, how do you think it ate? ______
Please answer these questions in your Word doc.
Phylum Chordata: Mosasaur Ok, here’s how this animal might have looked. https://sketchfab.com/3d-models/mosasaur-14b9244ebea34c05927f3cfcfbde7fe4 https://sketchfab.com/3d-models/mosasaurus-hoffmannii-83338897566c4288a8e5f10db623ff18
36. What living animal does this most remind you of? ______
Please answer these questions in your Word doc.
Phylum Chordata: Allosaurus https://sketchfab.com/3d-models/allosaurus-skull-and-jaw-703839dcc16f4b1fb4dc14bf9d3144c6 https://sketchfab.com/3d-models/allosaurus-fragilis-by-thomas- hanlon-911bd2ef8aee49fba398aa7f864b0daf
Geology 121 Lab 11: Mesozoic A, page 7 of 8 Check out the skull. 37. Is this a synapsid, anapsid, or diapsid? ______
38. Examining the teeth, what do they suggest about how this animal ate? ______
39. Try to find the brain case. You might be surprised by its size. What does that suggest about this animal? ______
Please answer these questions in your Word doc.
https://sketchfab.com/3d-models/allosaurus-fragilis-ed5b571066394deab73980f1a0c2fe47 https://sketchfab.com/3d-models/allosaurus-206f42dc22704ed08e4475e9eae19d5b
This model is a bit … much. But Allosaurus was essentially a smaller version of T. rex. Next time we’ll focus more on dinosaur species you’ve come to know and love…. from all those Jurassic Park movies, lol :p
Geology 121 Lab 11: Mesozoic A, page 8 of 8