2. Find and sketch a spumellarian radiolarian and a nassellarian radiolarian. Label all the features that you can. What depth is suggested by a sample with mostly spumellarians? With mostly nassellarians?

3. Calcareous sponges; these were the only reef-building animals in the Late Carboniferous. How do you think these sponge reef compare to modern coral reefs in size and wave-resistance?

4. Recent calcareous sponges. Sketch and label the osculum.

5. Look at the spicules of these fossil sponges. Which specimen provides more information about the sponges morphology? How would you explain this preservational difference?

6. Fossil and recent glass sponges. Locate the osculum on the recent sponge. What purpose do you think the tuft of spicule fibers serves? Where would you expect to find these sponges and why?

7. Stromatoporoids. These were the dominant reef-builders in the Ordovician, Silurian and Devonian. Sketch a close-up cross-section, showing lamellae and pillars (look at polished pieces if available). Sketch the upper surface, labeling mamelons and astrorhizae. Label any other features that you can see.

8. Archaeocyathans. This group of short-lived, bizarre fossils has been classified with a variety of other organisms. People cannot even agree as to which kingdom they belong to (some believe they are spongiomorphs; others believe they should be allied with algae). Distinguishing between a plant or animal seems like a simple problem, but one that has perplexed paleontologists when considering this group. How would you go about solving this fundamental paleobiological problem? What criteria would you look for to make this plant/animal distinction? Sketch a cross-section, labeling septa, intervallum, and central cavity.

Back to Chapter Six.