FOSSIL "FUN"DAMENTALS

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1 NAME DATE PARTNER(S) FOSSIL "FUN"DAMENTALS You are taking a stroll on a beach in Calvert or southern Charles County when you come across a shark s tooth laying in the sand at the water s edge. You pick it up and realize that this must be a fossil. Then you think What is a fossil? From what you know about fossils, list some of the properties that come to mind when you think about a variety of fossils. Picture from: Fossils are the remains or traces of animals or plants buried in the Earth's crust by natural processes. They are the preserved remains of living matter from the past. How do you think fossils form? Explain why you think that. What living things do you think will form the best fossils? Which probably will not form fossils? Explain why you think that. Let's Explore! Activity 1: Looking at the Characteristics of Fossils In the lab you will find collections of fossils that are typical of those found around the world and a set that is typical for Southern Maryland. Spend some time looking each of the collections. As you look at them, answer the sets of questions that follow. Explorations in Earth and Space Science PSC 121 Prince George s Community College 99

2 1. What characteristics do all of the samples have in common? 2. Do you find more evidence for plants or animals? Explain 3. Are there more representatives from land or marine organisms? Explain why your observation might be true. Activity 2: Modes of Fossil Preservation Let's consider how fossils are preserved. Look at the set of fossils labeled Modes of Preservation for this activity. 1. Do you see any original material, that is, unaltered material that was part of the original organism? List any you see. Why do you think these materials could be were preserved without alteration? 2. How do you think an image or replica of an organism be preserved even if the original material is not? Explain your answer. 100 Explorations in Earth and Space Science PSC 121 Prince George s Community College

3 3. Do you see any fossils that show external (outside) features? List and describe any you find. Are there any samples that show internal (inside) features? Describe any you find. Explain how these were probably made. 4. Are there any samples that show indirect evidence (such as film on a surface) of an organism's former presence? What are the characteristics? Activity 3: Am I Real? Is everything that looks like a fossil really a fossil? Examine the "AM I REAL?" box in the lab. Decide if the items are fossils or not. Be sure to include your justification. ID Real (Y or N) Justification A B C D E Explorations in Earth and Space Science PSC 121 Prince George s Community College 101

4 Activity 4: Going Fossil Hunting 1. Before you go fossil hunting here are a few questions. What general type of rock (igneous, sedimentary, metamorphic) do you need to find fossils? If you are looking for clams, what type of ancient environment do you need to find in the rock? If you are looking for dinosaurs, what type of ancient environment should you look for in the rock? Suppose you are going exploring for some fossilized organisms. A useful reference is a geological map which charts the geological ages of exposed rocks in an area. Locate a geological map of Maryland to use in planning your hunting expedition. When geological history you find that certain organisms lived over specific geological ranges of time. These fossils can narrow down the age of a rock you uncover. If looking for certain fossils, you need to find the right age rock. Let's plan a hunt! 2. Using the geologic map of Maryland and the fossil display in the hallway, determine where in Maryland you could find the fossils listed in the table below and the type of rock they can be found in. Fossil Time Range Rock Type Location dinosaurs Triassic-Cretaceous trilobites Ordovican-Cambrian shark teeth Tertiary (or Ternary) Will you have to travel very far to locate these fossils? Explain. What is the state fossil of Maryland? What type of creature is it? 102 Explorations in Earth and Space Science PSC 121 Prince George s Community College

5 DISCUSSION As you may have discovered in the exploration above, there are two major requirements for an organism to be fossilized: 1. hard parts such as a skeleton or shell 2. rapid burial in a protective medium such as the marine environment The chart below gives examples of organisms and their chances of being fossilized. HARD PARTS YES NO RAPID YES GOOD clams POOR jellyfish BURIAL NO POOR birds VERY POOR butterflies Fossils can be classified in two major ways. 1. Unaltered soft or hard parts - Fossils can be formed from material that is preserved without any alteration. Examples of this include frozen wooly mammoths, insects in amber, birds/mammals in the La Brea Tar Pits, shells of clams and snails, and mummified (dried) Hadrosaur (duck-billed dinosaur) skin. 2. Altered parts - Original material may be changed, recrystallized or replaced by different material (calcite in shell replaced by pyrite), or porous material may be filled by different material (bone/wood with silica). If original material is dissolved and the hollow impression filled, a mold is formed. This can show internal or external surfaces. Plants are commonly preserved as carbon films. In Prince George's County and the rest of Southern Maryland, the common fossils are unaltered and altered hard parts of mainly marine invertebrate shells. Beware of pseudofossils! As you discovered from the "AM I REAL" box, some inorganic structures may look like fossils but are not. Explorations in Earth and Space Science PSC 121 Prince George s Community College 103

6 DINOSAURS IN MARYLAND There have been limited dinosaur finds in early Cretaceous terrestrial (continental) sediments (Arundel clay) in a narrow belt between Baltimore and Washington. The area between Beltsville and Laurel in PG County has been fairly productive due to iron mining during the 1800's and clay mining for bricks (Maryland Clay Products still operates today). The last furnace (1916) to produce iron from Maryland ores was located at Muirkirk. What little fossil material exists is in the form of isolated bones, fragments, and teeth. The dinosaur fauna of Maryland are represented by: 1. small carnivores, specifically the coelurids and the ornithomimides 2. at least one large meat-eater, Dryptosaurus 3. the sauropod (probably a brachiosaur), Astrodon (or Pleurocoelus), assumed to be herbivorous 4. the large ornithopod, Tenontosaurus 5. Priconodon, a primitive armored dinosaur or ankylosaur SOME RESOURCES ON DINOSAURS IN MARYLAND The Maryland Geologic Survey web site contains many resources (factsheets and pamphlets) on fossils and fossiliferous rocks in Maryland formerly available only in print. Look for the ones listed below at: Maryland s Official State Fossil Shell Fossils in Counties of Maryland Fossil Collecting Sites at Calvert Cliffs Miocene Sharks Teeth Fossil Teeth of the Maryland Miocene Characteristic Fossils of Maryland Formations Astrodon johnstoni, The Maryland State Dinosaur Also worth noting are: Marc R. Gallup, A New Look at the Old Dinosaurs of Maryland, The Maryland Naturalist 32 (3-4), J.D. Glaser, Fossil Collecting in Maryland, Maryland Geologic Survey Publication ES4, Peter Kranz, Dinosaurs in Maryland, Maryland Geologic Survey Publication ES6, Martin Schmidt, Maryland's Geology, Tidewater Publishing, Explorations in Earth and Space Science PSC 121 Prince George s Community College