Lab 8: Ordovician 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 Ordovician 2. Phylum Cnidaria: Rugose Coral 3. Phylum Hemichordata: Graptolites 4. Phylum Echinodermata: Crinoids 5. Phylum Arthropoda: Trilobite 6. Phylum Arthropoda: Eurypterids 7. Phylum Bryozoa 8. Phylum Brachiopoda: Inarticulata 9. Phylum Brachiopoda: Artriculata 10. Phylum Mollusca: Gastropods 11. Phylum Mollusca: Cephalopods 12. Phylum Chordata: First Fishes
Introduction to the Ordovician Following the mass extinction ending the Cambrian, the Ordovician (488 - 443 Ma) marked a brilliant proliferation of Cambrian life into new and more complicated forms.
Many organisms secreted carbonate shells, usually first in the form of aragonite (CaCO3),
Geology 121 Lab 8: Ordovician, page 1 of 9 which often quickly converted to its polymorph calcite (CaCO3). This organic precipitation of carbonate became a major sedimentary rock type, as well as the material for shelly fossil preservation.
The evolution of fishes, especially in the latter part of the Ordovician, marks an area of particular interest to us—because it is ultimately from this line that we and all vertebrates descend.
We’ll organize this lab following this metazoan phylogenetic chart:
Many of these stations have multiple examples from each phylum.
Note them all, but I don’t expect you to prepare a page in your lab notebook for each one.
Think on picking a favorite and doing a deep dive into that one. Thee others you can think of in terms of giving you a sense of the variety within the phylum.
Phylum Cnidaria: Rugose Coral We’ve been seeing coral-like organisms since the archaeocyathids of the Cambrian, but now in the Ordovician we develop, for the first time, the type of corals we see abundantly today and which create the substate for so many other marine creatures to live.
Geology 121 Lab 8: Ordovician, page 2 of 9
Rugose corals can seem like a bilateral horn with many different internal divisions (septa, or singular, septum). These are distinguished from tabulate and scleractinia corals, which display radial symmetry.
It’s also worth pointing out that cnidarians are a group which displays some differentiated and specialized issues, which is very different from the sponges (which are still considered animals).
One feature among all currently living cnidarians is stinging cells (nematocysts), which are what zap you if you get stung by a jelly (or improperly named, a jellyfish). Other cnidarians include anemones and corals.
1. Zaphrentis https://sketchfab.com/3d-models/question-5b-zaphrentis-e972c78215144d4baec8cdc035d6183a https://sketchfab.com/3d-models/zaphrentis-sp-71d7536e9bc34a07a465443f44a81dc7
These models aren’t the best, but if you refer to the diagram above I think you can see the major components.
2. Check out this page: https://www.digitalatlasofancientlife.org/learn/cnidaria/anthozoa/rugosa/
What does a petroskey stone represent? ______
3. What can rugose corals tell us about the rotation of the earth? ______
Please answer these questions in your Word doc.
Phylum Hemichordata: Graptolites Note that we encountered graptolites in the previous lab, and what you’re seeing here are only part of the organism.
4. These pieces don’t give much a sense of the whole animal:
Geology 121 Lab 8: Ordovician, page 3 of 9 https://sketchfab.com/3d-models/graptolites-5185afa9e9c54bd6883bd34b078a96b3
5. UCB Check out this site https://ucmp.berkeley.edu/chordata/hemichordata.html for more info on graptolites.
What modern thing are graptolites most closely related to? ______
Please answer these questions in your Word doc.
Phylum Echinodermata: Crinoids Echinoderms have 5-fold symmetry and are the largest phylum to have no current terrestrial representatives.
This Ordovician fossil should look familiar: https://sketchfab.com/3d-models/asteroid-petraster-sp-d95ce0bb657b4f7e9ce12a6df026669a
Crinoids often form a long “stalks” with feathery filter feeding appendages. You may have never seen one in the wild today, but they were much more common during this period of life.
6. Crinoid fossils https://sketchfab.com/3d-models/crinoid-actinocrinites-gibsoni- pri-78779-23b51d9af0084d98b7246bb4e7579628 https://sketchfab.com/3d-models/giant-crinoid-fossil- photogrammetry-1dace5ec9d044a96b7eb241e94dd91fe https://sketchfab.com/3d-models/crinoid-daedalocrinus-sp- pri-49826-17c5f62826b449d68cd93083705d36b5
7. Crinoid stalk https://sketchfab.com/3d-models/crinoid-stem-phyllum- echinodermata-5d24fc433ff84cf28b3b92f920edd979
This is often how we see these as fossils. How difficult would it be to understand the entire organism if we only had this section? ______
Please answer these questions in your Word doc.
Geology 121 Lab 8: Ordovician, page 4 of 9 Phylum Arthropoda: Trilobites We’re going to have trilobites for some time to come, until their eventual demise at the Great Permian extinction.
8. Asaphus Intermedius https://sketchfab.com/3d-models/trilobite-asaphus-intermedius-pri-76770- f6805d2d272e4be99c1e5915849fbc88
What can you infer from the eyes here about the nature of predation at this time? ______
9. Hoplolichas & Acidapsis https://sketchfab.com/3d-models/trilobite-fossil-hoplolichas-plautini- f62ca7bb33714017afcce8127e0a7139 https://sketchfab.com/3d-models/acidaspis-fa666b397cd248fa880dce191c8ae78c
These models don’t quite get the defensive ornaments, so also check out this page: https://www.amnh.org/research/paleontology/collections/fossil-invertebrate-collection/trilobite- website/the-trilobite-files/trilobite-spines
What can you infer from the spines here about the nature of predation at this time? ______
Please answer these questions in your Word doc.
Phylum Arthropoda: Eurypterids Eurypterids are sometimes called “sea scorpions,” though they are only distantly related, but they certainly had a
Geology 121 Lab 8: Ordovician, page 5 of 9 stinger at the tail like modern terrestrial scorpions. Just be thankful these are not in today’s oceans! If I were that dude in the diagram above, I would definitely not try to shake hands/claws with them.
10. Nightmare Fuel #1 https://sketchfab.com/3d-models/eurypterid-fd3b0a66ca894126ba79f631e0f149b7
Oh man…
11. Nightmare Fuel #2 https://sketchfab.com/3d-models/eurypterus-remipes-72001474c99941369cac21981b35c493
Oh no, i can’t look anymore…
12. It’s ok, it’s only a fossil https://sketchfab.com/3d-models/eurypterus-ff287379008d43a4ad9a18cda7164c55
Ok, I can relax now…
Phylum Bryozoa Bryozoans are typically colonial filter-feeding organisms. This phylum has the distinction of being the only phylum to evolve since the early Cambrian.
13. See also: https://ucmp.berkeley.edu/bryozoa/bryozoa.html 14. And: https://www.uky.edu/KGS/fossils/fossil-bryos.php 15. And: https://www.digitalatlasofancientlife.org/learn/bryozoa/
16. Are bryozoans corals? ______
17. In what state are they the most common fossil? ______
18. What is another name for them? ______
19. How do bryozoa feed? ______
Please answer these questions in your Word doc.
Geology 121 Lab 8: Ordovician, page 6 of 9
Phylum Brachiopoda: Inarticulata For the brachipods, it might help you to note this diagram to keep them straight:
Inarticulate brachs, such as the lingulata, contain two shells that do not hinge together, but rather are just held together by muscle.
20. Lingula https://sketchfab.com/3d-models/lingula-fossil-97ba3f63bdc14339876c0c9c071dfcf7
Phylum Brachiopoda: Artriculata Articulate brachs have a hinge, providing more mechanical leverage for holding their shells together.
21. Platystrophia https://sketchfab.com/3d-models/platystrophia-laticosta- brachiopod-170da85cb9054119865c235cdca946bf
Rafinesquina https://sketchfab.com/3d-models/rafinesquina-alternata- brachiopod-2286ce8350b042888e483e3527a2450a
Check out the way the shells attach in the posterior, and you can see what is meant by a “hinge,” as opposed to how the inarticulata close. What other differences can you see? ______
Please answer these questions in your Word doc.
Geology 121 Lab 8: Ordovician, page 7 of 9 Phylum Mollusca: Gastropods Gastropods are a very common thing to find today, both in the ocean and on land.
22. Murchisonia https://sketchfab.com/3d-models/murchisonia-major-0118c33a32604fffae81b45aa8582dec
Is there anything you can see here that is different from modern gastropods? Or are they pretty much the same? ______
Please answer these questions in your Word doc.
Phylum Mollusca: Cephalopods Ortho means straight, and these Orthoceras examples are called “orthocones” because their shell developed like a straight ice cream cone. Nonetheless, they were fearsome predators with excellent eyesight. Modern nautiluses are related.
23. Treptoceras https://sketchfab.com/3d-models/treptoceras-crebriseptum-0403-contextcapture- fcb9868d83d14894bceb247065ec5c71
24. Cameroceras https://sketchfab.com/3d-models/cameroceras- animated-700998c177dd46cbb2f12ce8beb7e157
25. Some of these cephalopods, such as Cameroceras, were _giant_. To wit:
26. Check out this page: https:// www.digitalatlasofancientlife.org/learn/ mollusca/cephalopoda/
What are some of the other shell shape possibilities? ______
Please answer these questions in your Word doc.
Geology 121 Lab 8: Ordovician, page 8 of 9 Phylum Chordata: The First Fishes (Ostracoderms, Pteraspidomorphi) The Ordovician also marks the appearance of unambiguous vertebrates, the fishes. However, don’t get too excited for our phylum yet. These early fish had some major differences with modern fishes: they were armored, and lacked hinged jaws.
27. Astrapsis https://sketchfab.com/3d-models/les-premiers-vertebres-530-ma- astraspis-471ec7bfb92b40299bb9412169bc1733
How the heck do you think it ate? Could it have just lined up food? ______
Please answer these questions in your Word doc.
Geology 121 Lab 8: Ordovician, page 9 of 9