The Fossil Record Chapter 17.1

The fossil record provides evidence about the history of life on Earth The fossil record provides evidence about the history of life on Earth. It also shows how different groups of organisms, including species, have changed over time.

How Fossils Form The formation of any fossil depends on a precise combination of conditions. Most fossils form in sedimentary rock. (test question) sedimentary rock The weight of layers of sediment gradually compresses the lower layers and, along with chemical activity, turns them into rock. fossil formation

Radioactive Dating A half-life is the length of time required for half of the radioactive atoms in a sample to decay. (test question)

index fossil Scientists also use index fossils to compare the relative ages of fossils. To be used as an index fossil, a species must be easily recognized and must have existed for a short period but have had a wide geographic range. (test question)

The first organisms on earth were most like today’s bacteria The first organisms on earth were most like today’s bacteria. (test question)

Take five notes from the video Earth Science: Fossils Assignment Take five notes from the video Earth Science: Fossils