GEO 2: Historical Geology with Lab Lab 6: Fossils and Time Name: ______________________________ Date: ___________ Part I. Questions Reference Material: What is meant by Phylogeny or Phylogenesis? How is this related to evolution? “The central ideas of evolution are that life has a history—it has changed over time—and that different species share common ancestors.” University of California Museum of Paleontology http://evolution.berkeley.edu/evolibrary/article/evo_01 The common taxonomic subdivisions in descending order (Kingdom, Phylum, Class, Order, Family, Genus, and Species). There are five kingdoms of organisms: 1. Animalia (animals) 2. Plantae (plants) 3. Monera (bacteria and blue‐green algae) – Includes Stromatolites 4. Fungi (mushrooms, fungus) 5. Protista (included in Rhizaria): single‐celled organisms, – Includes Foraminifera/Fusulinids, Diatoms, Radiolaria The Animal Kingdom animals can be grouped into the invertebrates (animals without backbones) and the vertebrates. There are more than 20 invertebrate Phyla, but the chief ones that are preserved as fossils include: 1. Phylum Porifera ‐ the sponges (may include Archeocyathids, or in a separate Phylum) 2. Phylum Cnidaria (formerly Coelenterata) ‐ the corals and jellyfish 3. Phylum Bryozoa ‐ the colonial moss animals 4. Phylum Brachiopoda ‐ the brachiopods or lamp shells 5. Phylum Arthropoda ‐ the insects, crabs, shrimp, lobsters, trilobites and eurypterids 6. Phylum Mollusca ‐ the clams (Bivalves), snails (Gastropods), octopus, squid, nautilus, and ammonites (Cephallopods) 7. Phylum Echinodermata ‐ the starfish, sand dollars, sea urchins, crinoids, and blastoids The vertebrates belong to Phylum Chordata (referring to the nerve chord that extends down the center of the spine). Our goal with lab is to be able to identify the following common fossils and provide a general age range: Porifera (sponges), Trilobites, Brachiopods, Bryozoans, Cnidaria (corral), Mollusca – including bivalves, ammonites, gastropods, Echinoderms – including crinoids, blastoids 1. Provide a short definition of a fossil 1 | Page GEO 2: Historical Geology with Lab Lab 6: Fossils and Time 2. Describe how the following processes of fossil preservation differ: Permineralization compared to Replacement 3. Briefly describe what is meant by a “trace fossil” 4. List the seven common taxonomic subdivisions (start with Kingdom) 5. What is meant by Phylogeny or phylogenesis? How is this related to evolution? From Poort and Carlson (Historical Geology Interpretations and Applications): Fossil animals and, less commonly fossil plants are used to determine the relative geologic age of a sediment; the nature of the paleoenvironments, and the characteristics of an ancient area. Certain fossils are especially useful for age determination. These fossils are known as Index Fossils. Index Fossils must fulfill the following conditions: 1. Organisms should have lived during a relatively short period of geologic time and should have been abundant. 2. Organisms should have had a wide geographical distribution that was not strongly influenced by facies changes 3. Organisms should have distinctive appearance to be easily recognized. 6. Consider the following collections of fossils. Use the age ranges of these fossils to answer the following questions. Specimen 1 – Ordovician‐Permian Specimen 2 – Silurian‐Mississippian Specimen 3 – Cambrian‐Triassic Specimen 4 – Devonian‐Eocene Specimen 5 – Ordovician‐Jurassic Specimen 6 – Mississippian‐Recent a. Which is the best index fossil? b. Which is the poorest index fossil? c. What combination of fossils is the most definitive? 2 | Page GEO 2: Historical Geology with Lab Lab 6: Fossils and Time 7. All of the fossils named in the column below are trilobites. The columns have been correlated based on rock type and fossils. Use the age ranges of the trilobite species to determine the geologic time interval corresponding to the Cherty Limestone. 3 | Page GEO 2: Historical Geology with Lab Lab 6: Fossils and Time Lab Activities Part 1 – Shape and Symmetry. Getting to know the common fossils Use the attached drawings (as well as other lab books) to analyze the specimens provided in the lab. Match each specimen letter to one of the descriptions below. List the distinctive characteristics of the Phylum/Class. Specimen Symmetry/characteristics Taxonomic Group (Phyla and/or Class) Letter Phylum Bryozoa Phylum Cnidaria, Class Anthozoa ‐ colonial Phylum Porifera Phylum Echinodermata – Class Crinoidea Phylum Echinodermata – Class Echinoidea Phylum Mollusca ‐ Class Cephalopoda, Subclass Ammonoidea Phylum Mollusca, Class Bivalvia Phylum Brachiopoda Phylum Mollusca, Class Gastropoda Phylum Mollusca, Class Cephalopoda, Order Belemnitida (non‐coiled, no sutures) Phylum Arthropoda, Class Trilobita Phylum Cnidaria, Class Anthozoa, non‐ colonial – solitary Rugose (Order) Kingdom Monera, Cyanobacteria ‐ Stromatolite Kingdom Protista, Foraminifera Phylum Porifera/Archaeocyathid 4 | Page GEO 2: Historical Geology with Lab Lab 6: Fossils and Time Part 2 – Identify the fossil specimens provided to phylum using the enclosed key and resources. List the class for Cnidarians (Class Anthozoa), Mollusca (Classes: Bivalvia, Gastropoda, Cephalopoda), Arthropoda (Class Trilobita, Class Crustacea), and Echinodermata (Classes: Crinoidea, Blastoidea, Asteroidea, Echinoidea). List Archaeocyathids as Phylum Porifera. A. B. C. D. E. F. G. H. I. J. K. L. M. 5 | Page GEO 2: Historical Geology with Lab Lab 6: Fossils and Time Part 3 – Use the enclosed geologic range charts and Phyla information to answer the following questions. Be specific about class if different classes of phyla span different age ranges. 1. Which taxonomic group(s) were present during the Precambrian? 2. Which taxonomic groups were present during the Paleozoic Era? 3. Which taxonomic groups were abundant during the Mesozoic Era and which groups were either absent or had declined compared to the Paleozoic Era? 4. Which taxonomic groups were abundant during the Cenozoic Era and which groups were either absent or had declined compared to the Mesozoic Era? 5. Major extinctions occurred several times in the geologic past. What times of extinction are suggested by the geologic range information provide? Remember that not all members of a phylum go extinct during one of these events, but the total number of species may decline. 6. If you found a rock containing both Scleractinian corals and ammonoids, to which geologic periods might it belong? 6 | Page GEO 2: Historical Geology with Lab Lab 6: Fossils and Time Part 4 – Assign the following fossil assemblages to geologic age range (as specific as possible). Trilobites, Brachiopods, straight shelled Cephalopods, Archaeocyathids Rugose Coral, Crinoids, Blastoids Bivalvia, Echinoids, Gastropods Belemnites, Ammonites, Asteroids Part 5 Examine each of the samples (or sets of samples) provided and indicate: a. Fossil identified – to Phylum and/or Class b. The approximate time interval represented. Indicate the portion of the Era (or Period) for the Paleozoic Era. 1. Specimen Group 5A 2. Specimen Group 5B 3. Specimen Group 5C 7 | Page GEO 2: Historical Geology with Lab Lab 6: Fossils and Time Phylum Porifera – sponges: Globular, cylindrical, conical or irregular shape. Basic structure is vase‐like with pores and canals. Interior may be hollow or filled with branching canals. Solitary or colonial. Skeletal elements are called spicules, and they may be separate or joined. Composition may be calcareous, siliceous or organic material called spongin. The Cambrian Archaeocyatha is sometimes grouped with sponges or put into a separate phylum A. Diagram of an Archaeocyathid. B. is a transverse section >>>> (a) Rugose (b) Tabulate (c) Scleractinian Phylum Cnidaria – Corals and Jellyfish: 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. Corals have a hard calcareous skeleton, and may be solitary or colonial. Colonies are composed of many polyps living together. The "cup," in which an individual coral polyp sits, is called the Theca. Each theca is small (several millimeters to several centimeters in diameter), and roughly circular or hexagonal in shape. The theca is divided internally by vertical partitions called septae, arranged in a radial pattern. Types of corals are distinguished by presence or absence, and number of septae: The Paleozoic Rugose corals (or tetracorals) have septae arranged in multiples of four. The Mesozoic and Cenozoic Scleractinian corals (or hexacorals) have septae arranged in multiples of six. The Paleozoic Tabulate corals lack septae. Instead, they have horizontal plates within the theca called tabulae. Tabulae are one of the main features of the tabulate corals. Phylum Bryozoa ‐ Colonial (many microscopic individuals living physically united adjacent to one another). The individuals are called zooids, and they are housed in a hard "capsule" called a zooecium. The colony is called a zoarium. Individual zooecia (plural of zooecium) are very tiny (about the size of a pin‐hole, a millimeter or less in diameter). They are just large Bryozoans may be distinguished from corals enough to be seen with the unaided eye. The bryozoan because of the apertures in the skeleton are colony may resemble lace or a tiny net, may be much smaller. delicately branching, finger‐like, circular or dome‐ shaped. 8 | Page GEO 2: Historical Geology with Lab Lab