Earth & Space Science
You will conduct tests on newly discovered cells to determine if the cells are native to Earth.
After completing this tutorial, you will be able to complete the following:
Fossils can provide clues to past life on Earth and the evolution of organisms. They can be divided into two major categories. One category of fossil remains includes fossilized body parts such as bones, claws, teeth, and skin. Another type of fossil that scientists study is called fossilized traces. These include remnants of footprints, nests, and burrows that are records of the movements and behaviors of the organisms that left them.
There are four types of fossils including:
~ mold fossils (a fossilized impression made in the substrate)
~ cast fossils (formed when a mold is filled in)
~ trace fossils (fossilized nests, dung, burrows, footprints, etc.)
~ true form fossils (fossils of the actual animal or animal part)
Different types of fossils are often found in sedimentary rock layers, buried after years of sediments being deposited and compacted.
A fossil's position in sedimentary rock beds gives its age relative to other fossils. In undisturbed sedimentary rock the bottom layers are the oldest and the top layers are the youngest. Fossils found in the lower layers are older. Those found in the upper layers are younger.
The absolute age of a fossil can be determined by dating the fossil with radioactive isotopes. Radioactive isotopes have unstable nuclei that break down, or decay, and form other elements. These isotopes, such as Carbon 14, decay at a constant, known rate that scientists can measure to pinpoint the age of ancient rocks and fossils.
Sorting and identifying fossils are the first steps taken by paleontologists when studying the remains of organisms from the past.
After sorting fossils into groups that have similar physical characteristics, a classification key can be used to identify the organism they came from. Classification keys, also known as dichotomous keys, are useful tools for looking at characteristics of organisms and following branches that narrow down what species they belong to.
|Approximate Time||20 Minutes|
|Pre-requisite Concepts||Learners should know that there are two main types of cells: prokaryotic and eukaryotic. Learners should also be familiar with the main cell parts and organelles. Learners should be aware of the cell theory and its main tenants.|
|Course||Earth & Space Science|
|Type of Tutorial||Concept Development|
|Key Vocabulary||cartilaginous, chondryitchthes, classification, classification key, conical, cusp, dichotomous key, Earth, evidence, fossil, fossil evidence, geologist, identification, jaws, layer, multituberculate, paleontologist, rock, sandstone, scales, sedimentary, serration, shark, sickle, sorting, striation, teeth, vertebrae|