The Archaea are prokaryotic, and in that way they resemble bacteria but, the Archaea inhabit extreme conditions - temperatures above the boiling point of water, high pressures like those at the bottom of the ocean, or in extremely acid, alkaline or high salinity environments (conditions like those which may have been present on the early Earth or under the harsh conditions on other planets). The Archaea are genetically very different from normal bacteria, and are considered by some to be even more primitive. Information on the fossil record of the Archaea can be found at http://www.ucmp.berkeley.edu/archaea/archaeafr.html.

All of the fossils that we will examine in this lab are animal remains. Some plant fossils will be studied in the Preservation Lab. Animals and plants have some characteristics in common, but they also have basic differences. Plants manufacture their own food by photosynthesis (i.e., they are producers or autotrophs). Furthermore, plants have no freedom of movement. Animals cannot manufacture their own food; they must eat (i.e., they are consumers, or heterotrophs). Animals have at least some freedom of movement, however, there are many types of animals that live attached to rocks or other organisms.

KINGDOM ANIMALIA

1. PHYLUM PORIFERA (sponges)

Name: Cnidaria are named for stinging cells called cnidoblasts. The name Coelenterata means "hollow" (coel) + "gut" (enteron).
Chief characteristics: Radial symmetry. Corals have a hard calcareous skeleton, and may be solitary or colonial. Colonies are composed of many polyps living together. The skeletal parts formed by polyps are called corallites. Each corallite is a small (several millimeters to several centimeters in diameter), roughly circular or hexagonal opening, with internal radial partitions called septae in the Rugose and Scleractinian corals. Tabulate corals lack septae. (Corals may be distinguished from the bryozoans based on the size of the corallites; in bryozoans, the apertures are much smaller; generally 1 millimeter in diameter or less).
Geologic range: Late Precambrian (Proterozoic) to Recent for the phylum. See ranges of each order, below.
Mode of life: Corals live attached to the sea floor, primarily in warm, shallow marine environments.

Many living cnidarians are soft-bodied (such as jellyfish and sea anemones), but only those cnidarians which are able to form hard skeletal structures (such as corals) are readily preservable as fossils. Hence, the only class of cnidarians that we will study is Class Anthozoa, the corals.

Jellyfish, Chattanooga Aquarium	Jellyfish, North Carolina Aquarium	Sea anemones, Baltimore Aquarium

CLASS ANTHOZOA (corals and sea anemones)

A. SUBCLASS RUGOSA

Most rugose corals are solitary and conical (shaped like ice cream cones). Septae are visible in the circular opening of the cone. Some rugose corals are colonial, having hexagonal corallites with septae (such as Hexagonaria from the Devonian of Michigan).
Geologic range: Ordovician to Permian - all extinct. (Note: textbook says Cambrian to Permian.)

Solitary rugose coral. Acrophyllum, 365 my, Devonian, New York. About 10 cm long.

Colonial rugose coral, Acervularia davidsoni, 365 my from the Devonian of Iowa.

B. SUBCLASS TABULATA

Tabulate corals are colonial and resemble honeycombs or wasp nests. They lack septae.
Halysites is called the chain coral because its coral tubes are attached in wavy lines resembling a chain.
Geologic range: Ordovician to Permian - all extinct.

Tabulate coral, Halysites, the chain coral.

Tabulate corals. Top view (left) and side view showing tabulae (right).

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C. SUBCLASS ZOANTHARIA
ORDER SCLERACTINIA

Scleractinian corals are the modern corals. Most are colonial, but some are solitary. Many are reef-builders. In some, skeletal material is deposited between corallites (such as in Astrhelia palmata from the Miocene of Maryland).
Geologic range: Triassic to Recent.

Scleractinian corals

3. PHYLUM BRYOZOA (bryozoans)

Name: Name means "moss" (bryo) + "animal" (zoa).
Chief charactristics: Colonial (many microscopic individuals living physically united adjacent to one another). Individuals are very tiny (a millimeter or less in diameter) - just large enough to be seen with the unaided eye. Bryozoans may be distinguished from corals because of the apertures in the skeleton are much smaller. May resemble lace or a tiny net, may be delicately branching, finger-like, circular or dome-shaped. Archimedes from the Mississippian has a cork-screw-like central axis with a fragile net-like colony around the outer edge which is usually broken off.
Geologic range: Ordovician to Recent.
Mode of life: Widespread in marine environments. A few live in freshwater lakes and streams. Colonies may be encrusting (a thin layer covering a rock or shell), erect (attached at the bottom and standing up like a tree - some are branching, others are sheet-like), or massive (compact and nodular).

There are several classes and orders, but they will not be considered in this lab.

Bryozoan, Heterotrypa from the Late Ordovician (440 my) of Kentucky. About 5 cm across.

4. PHYLUM BRACHIOPODA (brachiopods or lamp shells)

Name: Name means "arm" (brachio) + "foot" (pod).
Chief characteristics: Bivalved (two shells), each with bilateral symmetry. The plane of symmetry passes through the center of each shell or valve. The two valves differ in size and shape in most. Sometimes the larger valve will have an opening near the hinge line through which the pedicle extended in life.
Geologic range: Lower Cambrian to Recent.
Mode of life: Inhabitants of shallow marine environments; they generally live attached in a fixed position on the sea floor.

A. CLASS INARTICULATA

Primitive brachiopods with phosphatic or chitinous valves; no hinge. Valves held together with muscles and soft parts.
Lingula is a well known inarticulate brachiopod.
Geologic range: Lower Cambrian to Recent

Inarticulate brachiopod, Lingula cuneata, from the Silurian Medina Sandstone, Medina, New York.

Inarticulate brachiopod, Rome, GA.

B. CLASS ARTICULATA

Brachiopods with calcareous valves attached together with a hinge.
Some of the more common articulate brachiopods are Pentamerus, Rafinesquina, Atrypa, Leptaena, and Spirifer.
Geologic range: Lower Cambrian to Recent

Articulate brachiopod fossils

5. PHYLUM MOLLUSCA (clams, oysters, snails, slugs, Nautilus, squid, octopus, cuttlefish)

6. PHYLUM ARTHROPODA (insects, spiders, shrimp, crabs, lobsters, barnacles, ostracodes, trilobites, eurypterids)

7. PHYLUM ECHINODERMATA (starfish, sea urchins, sand dollars, crinoids, blastoids)

Name: Echinodermata means "spiny" (echinos) + "skin" (derma).
Chief characteristics: Calcite skeleton with five-part symmetry.
Geologic range: Cambrian to Recent.
Mode of life: Exclusively marine. Some are attached to the sea floor by a stem with roots; others are free-moving bottom dwellers.

A. CLASS CRINOIDEA (crinoids or "sea lilies")

Crinoids are animals which resemble flowers - they consist of a calyx with arms, which is attached to the sea floor by a stem of calcite disks called columnals. Some living crinoids are swimmers, and not attached.
Geologic range: Ordovician to Recent.

Crinoids

Fossil crinoid stems

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B. CLASS BLASTOIDEA (blastoids)

Blastoids are extinct animals with an armless bud-like calyx on a stem.
Geologic range: Ordovician to Permian - all extinct.

Fossil blastoids. Image courtesy of Paleontological Research Institution

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C. CLASS ASTEROIDEA (starfish)

Starfish are star-shaped echinoderms with five arms.
Geologic range: Ordovician to Recent.

Modern starfish.

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D. CLASS ECHINOIDEA (sand dollars and sea urchins)

Echinoids are disk-shaped, biscuit-shaped, or globular. Viewed from above, they may be circular or somewhat irregular in shape, but with a five-part symmetry.
Geologic range: Ordovician to Recent.

Modern echinoid with spines attached.

Modern sand dollar with its tiny spines still attached.

 

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CLASS GRAPTOLITHINA

SUMMARY

In this lab, you were introduced to seven phyla and additional classes and orders.

1. PHYLUM PORIFERA (sponges)

2. PHYLUM CNIDARIA [or COELENTERATA] (corals, jellyfish, and sea anemones)

   Class Anthozoa (corals)

   1. Subclass Rugosa (rugose corals - extinct)
      
   2. Subclass Tabulata (tabulate corals - extinct)
      
   3. Subclass Zoantharia Order Scleractinia (modern reef-building corals)
      

3. PHYLUM BRYOZOA (bryozoans)

4. PHYLUM BRACHIOPODA (brachiopods)
   1. Class Inarticulata
      
   2. Class Articulata

5. PHYLUM MOLLUSCA (molluscs)
   1. Class Bivalvia [sometimes called Pelecypoda] (clams and oysters)
      
   2. Class Gastropoda (snails)
      
   3. Class Cephalopoda (nautiloids and ammonoids)
      
      1. Order Nautiloidea
         
      2. Order Ammonoidea
         
      3. Order Belemnoida
         
      4. Order Sepioidea
      5. Order Teuthoidea
      6. Order Octopoda
   4. Class Scaphopoda (tusk shells)
   5. Class Monoplacophora
   6. Class Polyplacophora (or Class Amphineura) (chitons)

6. PHYLUM ARTHROPODA (insects, spiders, shrimp, crabs, lobsters, barnacles, ostracodes, trilobites, eurypterids)
   1. Subphylum Trilobita
   2. Subphylum Chelicerata
      1. Class Xiphosura
      2. Class Eurypterida
      3. Class Arachnida
   3. Subphylum Crustacea
      1. Class Ostracoda
      2. Class Cirripedia
      3. Class Malacostraca
         1. Order Decapoda
         2. Order Isopoda
   4. Subphylum Labiata
      1. Class Insecta

7. PHYLUM ECHINODERMATA (crinoids, blastoids, starfish, sea urchins, sand dollars)
   1. Class Crinoidea
   2. Class Blastoidea
   3. Class Asteroidea
   4. Class Echinoidea

8. PHYLUM HEMICHORDATA (graptolites)
   Class Graptolithina

Go to Invertebrate Macrofossils Lab - Exercises

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This page created by Pamela J. W. Gore, pamela.gore@gpc.edu
Georgia Perimeter College

July 1, 1998
Modified April 7, 1999
Modified March 2, 2000
Modified June 6, 2001
Modified March 25, 2003
Modified December 12-13, 2003
Modified Decembr 3-4, 2004
Modified December 10, 2004
Photo added June 23, 2005
Web updates, photos added June 22, 2008