|GL21A Practical 1 Porifera & Cnidaria (Hydrozoa, Tabulata & Rugosa)
1. The skeleton of this sponge is made of what material?
2. What grade of sponge is this?
3. What characteristics suggest that these specimens are sponges? How do they differ from the sponges seen in question one and two?
3A. Astraeospongia meniscus (Silurian, Tennessee, USA)
4. Make a small sketch of this stromatoporoid specimen (Actinostroma sp.) labelling the laminae, pillars and asterorhizae.
Sponge Trace Fossils
5. Clionid sponges produce a common trace fossil. They bore into shell or rock material (hardgrounds especially). They are important bioeroders, making small circular borings that when later filled may make beaded chains.
By comparison with the modern specimen here describe the preservation of the fossil specimen provided.
Is any skeleton preserved? Clionids belong in what Class?
6. Recent and Eocene ‘fire’ corals from Jamaica ( Millepora sp.). Note the lack of septa and axial structures. How can you tell the gastropores from the dactylopores?
7. Most octocorals (sea whips & sea fans) lack a mineralized skeleton and aren’t commonly preserved. One group, the stony octocorals, does fossilize readily and are common on Cretaceous to Paleogene reefs from the Caribbean. Modern forms, blue coral, are known only from the Indo-Pacific. They look superficially like corals but with very weak pseudosepta. Note the similarity between the modern and Cretaceous forms.
8. Describe the corallite arrangement for each the following.
Draw a longitudinal sketch through a Favosites sp. corallum. Label tabulae and mural pores.
9. Lithostrotion sp. What kind of corallite arrangement does it have?
10. Sectioned specimen of Aulophyllum fungites (#68, Carboniferous, Scotland, UK). Make a labelled sketch of a transverse view of this solitary coral. Why is this coral a member of the Rugosa?
10. B. Streptolasmatina sp. (Ordovician, Iowa, USA) What shape is this corallum?