Fossils can be found all over the world, often in layered rock formations. To determine the age of the rock layers within an area, geologists and paleontologists use a technique called radiometric dating. Determining the age of a rock layer allows scientists to determine the age of the fossils within it. Some of the more exciting fossil discoveries are of dinosaurs, which existed on Earth between 230 and 65 million years ago. Examine this map. Click the map to zoom in, and drag the magnifying glass for a closer look. The map shows where prehistoric rocks formed during the Triassic, Jurassic, and Cretaceous time periods, the same periods when dinosaurs walked on Earth. Based on the map, what is the closest location to you where dinosaurs are likely to have lived? Course Activity: The Fossil Record Question Select the correct location on the image. As additional layers of sediment cover an organism that is being fossilized, the organism is typically forced farther and farther below ground level as it ages. This layering of sediment can create fossils within different layers that build on top of each other. Scientists can use the order of the fossils within the layers to determine the relative age of the fossils. Using the image below, identify the position of the oldest fossil.