GG 101L NAME ________________________ Semester: _______________ SECTION (Weekday and time)_____________________

Lab # __: Fossils I. Fossil Identification Fossil identification can be tricky, and obviously it can’t all be learned in 3 hours. There are often subtle differences between the specimens that even the experts can miss, or identify incorrectly. Never-the-less, now that you have read the incredibly exciting Paleontology chapters, and with the help of some hints below, you are ready to identify some of the more common fossil samples. The major Phyla that we are going to be looking at are: 1. Cnidaria (Fig. 10.27): This is pronounced “ni-dare-e-ah,” and includes corals, sea anemones, and

jellyfish. The corals are the most important class of Cnidaria, and include the order Rugosa (look like curved horns or ice cream cones), order Scleractinea (colonial corals that include modern day coral), and order Tabulata.(colonial corals that went extinct, along with 90% of all life(!), at the end of the Permian). Rugosa corals are horn-shaped (e.g., Lophophyllum, Streptesasma, Heliophyllum, Zaphrenthis), and have obvious septa, which are radiating pie-shaped spaces. Scleractinea corals are usually colonial (e.g., Favia, Acropora, Flabellum), and also have obvious septa. Tabulata corals have septa, but they are usually not very obvious (e.g., Halysites, Syringopora, Favosites), and the divisions don’t extend all the way from the outer margin to the center. Instead, tablular divisions (hence the name) between growth levels are prominent.

2. Brachiopoda (Figs. 10.34, 10.35): Brachiopods are two-shelled animals that look very similar to clams but if you take the halves apart, the top and bottom pieces are not symmetrical to each other. Instead, Brachiopods are symmetrical across a plane that is perpendicular to the seam separating the two shells.

3. Bryozoa (Fig. 10.30): These are colonial reef-builders that sometimes resemble Cnidaria. The key way to tell them apart is that the little pores are farther apart (e.g., Constellaria, Hallopora) and usually aren’t divided into obvious septa. A totally different type of bryozoan is Fenestella, which looks kind of like lace or Chex cereal.

4. Echinodermata (Figs. 11.30 – 11.38): These have 5-fold rotational symmetry, and include modern-day sea-stars, sand dollars, and sea urchins. Class Echnoidea (echnoids) are kind of like star fish with their arms pulled in (Fig. 11.30). Sometimes they get squooshed when they’re preserved, and the 5-fold symmetry is lost). Class Crinoidea (crinoids; Figs. 11.33-11.36) look like plants, but they’re animals. They attach to the ocean floor, and have a long segmented stem. At the top of the stem is the calyx and some feathery arms. Usually what is preserved are round segments of the stem, but sometimes the feathery calyx is preserved. Class Blastoidea (blastoids; Figs. 11.37, 11.38) grew in a manner similar to crinoids, but the calyx shows obvious 5-fold symmetry).

5. Mollusca (Figs. 11.4, 11.6, 11.10, 11.11): This is a large phylum and it includes a number of animals that don’t really look like each other. These include the class Bivalvia (bivalves; Fig. 11.4), including clams and mussels. Bivalvia have 2 shells and unlike brachiopods, they are not symmetric across a plane perpendicular to the seam between the two shells. Some Bivalvia are symmetric across the plane where the two shells join. The class Gastropoda (gastropods; Fig. 11.6) includes snails and slugs. Gastropoda are coiled but have no symmetry. The class Cephalopoda (cephalopods) includes nautilus, octopuses and squids. It’s pretty difficult to find a fossil octopus or squid, but fossil nautiluses and their now-extinct relatives called ammonites are common. Most nautili (Fig. 11.10) and ammonites (Fig. 11.11) are distinctive because they are

2 coiled and are symmetric across a plane perpendicular to the axis of the coil. A third type of cephalopod, belemnites (Fig. 11.14), look kind of like bullets.

6. Arthropoda (Figs. 11.21, 11.22): The most commonly preserved (and famous) fossils from this phylum are Trilobites, which show bilateral (i.e., left-right) symmetry. Sometimes trilobites fossils are rolled up and don’t look like you expect. Modern Arthropods include crustaceans, spiders, and insects.

7. Hemichordata (Fig. 11.40): These were probably colonial organisms along a common stem (class Graptolithina; graptolites). The individual colonies look like teeth or a saw, and they commonly occur in black shales.

A checklist/flowchart of hints for fossil identification. Is there any symmetry? NO: Cnideria, Bryozoa, Hemichordata, some Mollusca Obvious septa? Yes: Cnideria (Rugosa or Scleractinia – both may be colonial) No: Cnideria (Tabulata), Bryozoa, Hemichordata, some Mollusca Colonies: Openings on the same surface and touching? Yes: Cnidera (Tabulata) Openings on the same surface but separated? Bryozoa Arranged along a stem? Yes: Graptolite class of Hemichordata Looks like lace? Yes: Fennestrella class of Bryozoa Individual with coiled shell? Yes: Gastropoda class of Mollusca YES: bilateral: (Brachiopoda, Arthropoda, some Mollusca) Two shells? Yes: Brachiopods, Bivalvia class of Mollusca Symmetric across a plane perpendicular to the seam between shells? Yes: Brachiopoda Not symmetric across a plane perpendicular to the seam between shells, but usually symmetric across a plane parallel to the seam between shells? Yes: most Bivalvia One shell? Yes: Cephalopoda class of Mollusca (Nautilis, Ammonites, Belemnites) No shell, but with head, legs, etc: Arthropoda YES: 5-fold: Echinodermata (Echnoidea, Blastoidea classes) YES: radially symmetric: Echnoidermata (stems of Crinoidea class)

II. Basic Fossil Identification

3 Look at the tray of unknowns and try to fill in as much of the table as you can. You are not expected to identify the class correctly (but you can try), but take your time identifying the phylum! It will be helpful to use the figures in the two Fossils chapters, along with the information above. Fossil #

Simple Sketch Symmetry type (if any)

Phylum Class (if you can)

How do you know?

1

2

3

4

5

6

7

4 Fossil #

Simple Sketch Symmetry type (if any)

Phylum Class (if you can)

How do you know?

8

9

10

11

12

13

14 FRA-GILE !!

15

5 Fossil #

Simple Sketch Symmetry type (if any)

Phylum Class (if you can)

How do you know?

16

17

18

III. Identification of Multiple Fossils Looking at sample 19, identify fossils from as many phyla as you can. SAMPLE IS FRAGILE!! Simple Sketch Phylum

6 IV. Identification of Hawaiian Fossils Go out into the hallway near the door to room 708, and look in the display case. In this case there are several fossil samples collected around Hawai‘i. These fossils are significantly younger than the other fossils you have been looking at. See how many you can identify. Fossil # Simple sketch Phylum Class 83

2

74

15

80

7 V. Putting Fossils to Use for Geologic Mapping OK, so now you can identify fossils – big deal! Is this a useful skill? In the days before radiometric dating, geologists knew which fossils came from which geologic ages, but not how old they were in absolute years. Thus they could only determine relative age. But as you’ve already learned, relative age is all you need if you are going to figure out a geologic structure such as an anticline or syncline. On the next page is a map with fossils that have been found at certain locations. Assume that each fossil comes from the geologic time when that particular fossil type was most abundant. The figure below shows the age ranges of various fossil types, with the black part of each column indicating when they were most prevalent. For example, note that although bivalvia has been around since the Ordovician, they’ve only been abundant since the Tertiary. Then complete the geologic map. You should be able to add contacts that separate rocks containing different fossils, draw representative strikes and dips, and structural symbol(s). Then explain what your geologic sructure is, and how you figured it out.

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