Invertebrate Paleontology Laboratory
Lab #5
Bryozoa
1. A recent encrusting bryozoan colony on a scallop shell fragment. Do you think the scallop was alive or dead when the shell was encrusted?
2. This is a piece of a Middle Devonian cephalopod from the Butternut member of the Skaneateles Formation at Lake Moraine Quarry in central New York. Notice that a portion of this cephalopod has been encrusted by bryozoa. Do you think this bryozoan is utilizing food settling from above or carried by the currents?
3. This sample contains several forms of ramose bryozoa from the Ordovician of Ohio. Based on the growth forms, do you think these bryozoa utilizing food settling from above or food carried by currents? Sketch the specimen and label the monticules.
4. A very robust zoarium of Monticulipora also from the Ordovician of Ohio. Note the prominent monticules from which this specimen got its name. What purpose do you think the monticules might serve? Is this an encrusting, ramose, or massive form? Sketch the specimen.
5. An Ordovician bryozoan fragment from Ohio. Sketch a portion of the surface features and the broken surface (marked by the black dot). How do the surface features relate to those found on the broken surface?
6. These specimens are distinctive fenestrates called Fenestella. Sketch 6B and label the fenestrules and dissepiments. What was the function of the fenestrules?
7. Carefully examine the largest bryozoan in this slab. Is this a ramose, massive, or encrusting form? Would you find this form on a soft of firm substrate? Why?
8. Archimedes, a very distinctive fenestrate bryozoan found only in rocks of Mississippian and Permian age. Sketch one of the samples, adding arrows to show the path of water flow around this form. The actual specimens (8B) sometimes attain sizes comparable to those of the models (8A).
9. Examine this thin section of bryozoa from the Lower Devonian Manlius Formation of central New York.
10. Prasopora simulatrix , a trepostome bryozoan from the Ordovician Galena Formation in Cannon Falls, Minnesota. Sketch the sample in life position.
11. This red sandstone contains several bryozoan fossils. Are they molds or casts? Because we cannot examine the internal characters of the zoarium in thin section, it would be nearly impossible to classify these specimens at the species level. Is this a ramose, encrusting, or massive form? Does this form utilize food settling from above or carried by currents?
12. Chunks of bryozoan limestone from the Early Miocene Torquay Basin at Jan Juc, Australia. This limestone represents the skeletal remnants of a "meadow" of chelistome bryozoa. Sketch sample E12A and identify the growth forms you see.
13. Examine each thin section. Sketch 13C labeling the autopores, diaphragm, mature and immature regions; and 13D labeling the autopores, diaphragm, and mesopores.
Bryozoa | Gymnolaemata | Stenolaemata