Footprints have been found to have formed from the Mississippian epoch up to present time. The most notable and numerous footprints that have been found belong to the reptiles of the Triassic period: the dinosaurs. Many reptile tracks have been found in the Upper Triassic shaly sandstone of the Connecticut Valley.
Like most trace fossils, tracks and trails do not tell us the specifics on the organism in question. However, they do tell us something about its behavior. In addition, because tracks and trails cannot be preserved out of place, we can be quite sure that the fossils are found was where the organism lived.
Thus, tracks and trails are often used to interpret, among other things, the environmental conditions that existed around that the organism. Some tracks or trails left by organisms show a systematic pattern where an area of sediment surface is densely and evenly covered with no overlaps. This indicates systematic searching behavior and thus is invariably interpreted as feeding traces.
Conversely, some tracks or trails are random in their pattern. These types of markings are more often regarded simply as evidence of the organism's locomotion without any implied purpose e. Sometimes, tracks and trails do tell us something about the organism. In the case of dinosaur footprints, the footprints give us a hint as to the size of the dinosaur.
Dinosaurs belong to a group of reptiles known as archosaurs. Modern day archosaurs include crocodiles and birds. An archosaur is defined by an extra hole in the skull, located in front of the eye. Dinosaurs are further defined by a hole in the middle of the pelvis. No other animal on Earth has ever exhibited this feature. The hole in the pelvis allowed dinosaurs to walk with their legs directly beneath them, as opposed to the sprawling stance of other reptiles.
Dinosaur footprint trace fossils have been discovered on all continents except Antarctica. They have been found in layers of sedimentary rock ranging in age from million years ago to 65 million years ago. Paleontologists have learned much about dinosaurs from their footprints, mainly by comparing them with living animals.
Mammals are the best modern organisms for comparison because they walk erectly, like the dinosaurs. For example, elephant tracks and Apatosaurus dinosaur tracks are very similar.
What is a Fossil? How Fossils Form. Fossils From Living Things. Fossil Footprints. Skip to main content. K-5 GeoSource. PDF version Teaching and Learning Focus In the last investigation, students learned about body fossils, fossils that are the actual organism or some part of it or the imprint of the organism or some part of it. Materials Needed Per group: Plaster of Paris plastic measuring spoons stirring sticks water milk carton with the top portion cut off two measuring cups non-stick cooking spray brown paint paint brush plastic dinosaur models safety impact goggles for each student blunt knives to split Plaster of Paris Images to be viewed by the class: Images of Footprints Images of Trace Fossils For the instructor: flip chart or whiteboard markers Safety Use disposable craft sticks for mixing the Plaster of Paris.
Setting the Scene Many of your students will not think of ancient tracks, trails, burrows, feeding marks, and resting marks preserved in rock as fossils. Image of a Footprints Word Document 2. What may have made the imprints in the sand or mud? What can you tell about the size of whatever made the imprints?
What does the pattern of the imprints tell you about the behavior of whatever may have made them? Presenting the Investigation Question After the scene is set, introduce your students to the investigation question: How does a footprint become a fossil? Have your students brainstorm ideas about how this investigation question could be investigated. How would you design an experiment that could be used to test the investigation question?
What materials would you need? What would you have to do? What would you measure? How long would the experiment take? Assessing What Your Students Already Know In the last investigation, students determined that fossils form as sediments turn to rock. Here are some questions that your students can discuss, in pairs, then in groups: If a footprint is made by an animal in sediment, such as sand, and the sediment turns to rock, what do you think would happen to the footprint?
What can the footprints left behind by an animal tell you about what the animal was like? Have your students share their ideas with the class and record them as a list on a flipchart. Ask students the following: What would you like to learn about how a footprint becomes a fossil?
Exploring the Concept Explain to students that they will be making fossilized dinosaur footprints using Plaster of Paris and model dinosaurs. Each group will receive one or more dinosaurs. Groups should try not to let other groups see what their dinosaur s looks like.
Have students pour one cup of pre-mixed Plaster of Paris in the bottom portion of a milk carton. They should add more water, if necessary, to make a soupy mixture. Ichnofossils, also known as trace fossils, are geological records of the activities and behaviors of past life. Some examples include rock evidence of nests, burrows, footprints, and scat.
These fossils are different from body fossils that preserve the actual remains of a body such as shells or bones. Some of the trace fossils found in Denali have been linked to body fossils from similar-aged rocks on the North Slope or Talkeetna Mountains.
These linkages provide scientists with more definitive identities than are known from trace fossils alone. What is for dinner? Trace fossils help to give us a seat at the ancient dinner table. Probe marks in the ground near bird tracks imply that the birds were using their beaks to dig for food. Invertebrate burrows found in the same rocks likely provide the answer to what tasty food the birds were eating.
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