The worksheets in this set looks at how fossils are used as tool to understand past life on Earth.

When a living thing dies, it usually decays (disappears). Many times though, dead organic life will be captured in a substance that preserves it. When this happens in a substance that can hold it for hundred and even thousands of years, we refer to it as a fossil. The word "fossil" even means "dug up". Studying fossils help us understand past life. Some fossils can also be just evidence of past life, like a preserved footprint or an egg. When we put a bunch of fossils together we can get a pretty good idea of what life was like in early times. The oldest fossil that we have uncovered is about 3.8 billion years old. The hard body parts (skeletal remains) are most likely to be well-preserved as a fossil. This means creatures that lack a spine are rarely found in this form. When we take into account the collective number of preserved living things that we find and carbon date them to determine how old they are, we can get a pretty good picture of what life was roughly like at each time period.

The worksheets spend a good deal of time on the fossil record over time periods and how fossils are used as a tool to understand evolution. These worksheets help students understand how to look back in time through the use of the fossil record. It helps them understand the evidence that exists to understand the possibility of the evolution of species. We encourage them to create their own questions and conclusions.

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Evidence Worksheet

Evidence For Evolution

For the statements below, write the letter of the type of evidence above this best matches. Five types of evidence for evolution are comparative embryology, homologous morphological structures, fossils, vestigial organs, and biochemical homologies.

Record Worksheet

The Record

Label fossil layers by age. Number the oldest layer 1. Write a 2 on the next oldest layer and so on. What layer would contain the most recent animal and plant remains? Why?

Layers Chart Worksheet

Layers Chart

Pieces of rock broke off of the ledge below. Within the pieces of rock various fossils were found. Match the key to what you have found.

Fossil Layers Worksheet

Fossil Layers Question Sheet

Name two fossils that are younger than the dinosaur Skull. Which was the oldest and youngest based on their layered position. We can also compare this to the fish skeleton.

Layers Graphic Organizer

Layers Graphic Organizer

Cut out all the fossils from page 1. Paste the in order of age below.

How Fossils Form

Getting children interested in science can be a challenge. However, there are some topics that are reliable crowd-pleasers, including space, volcanoes, and dinosaurs. Along with dinosaurs, most of us have also found ourselves fascinated by the fossils that are part and parcel of palaeontology – often without understanding how they were formed in the first place.

They form when living organisms (such as plants and animals) die and are covered in sediment. This is followed by anaerobic decomposition, which breaks down the organism's soft tissue. The hard bones are left behind, and the sediment hardens into rock, forming fossils.

However, this is only one way in which fossils can be formed. This article will look at this method in further detail and also explore other fossilization methods, answering any questions you may have about their formation.

Most Common Type of Fossilization

The most common type of fossilization is known as permineralization.

As mentioned above, it involves the anaerobic decomposition of the soft tissues of a living organism after it is buried under sediment. Once the soft tissue decays away, groundwater seeps into the remains, and the minerals in the groundwater fill the empty spaces in the remains.

Over time, these minerals fully replace any remaining organic materials and harden, along with the sediment in which the hard bones or shells are encased, forming rocks that we recognize as fossils. This process is also known as petrification.

Other Types of Fossilization

Permineralization is the most common type of fossilization – but it isn't the only one. Some other types include:

Replacements or Impressions

These fossils follow the same formation path as permineralized ones. That is, until groundwater enters the picture.

Unlike permineralization forms, in these cases, the water dissolves away the hard bones, leaving an empty space in the rock shaped like the organism. These are known as molds.

In some situations, minerals fill the mold after the organism dissolves completely. These mineralized fossils are known as casts.


As the name suggests, compression fossils are formed when a three-dimensional organism is flattened by the weight of sediment or water to form two-dimensional remains. These forms are most commonly plant fossils.

In some cases, the rock holding the fossil may split naturally, with sections of the remains either attached to both halves or creating a mold on one half. These are known as slab and counter slabs.


While fossils most commonly form around the remains of living organisms, they can also form around the activity of an organism. This includes the footprints and burrows of organisms. Several footprint fossils grouped together, showing the movement of an animal, are known as trackways. Trackways may also include other evidence of the organism's movement, such as tail and wing impressions.

Coprolites are another important type of trace fossil. These are essential fossilized feces of animals and are used to examine the diet of the animal they came from.

Soft Tissue Preservation

In rare instances, not only is the hard bone and shell matter of an organism preserved, but their soft tissues can also be preserved.

This happens in very rare cases when the body of an organism is quickly buried in a low oxygen environment very soon after death. The best-known examples of this happening are when an organism is wholly encased in another material soon after death, such as ice, tar, or tree resin.

The resulting fossils are exceptionally well-preserved and provide scientists with a wealth of important information.

Final Thoughts

Fossils are an essential window into the Earth's past. They help us better understand where we came from and the history of our planet. They are formed following the death of a living organism, including ones as small as pollen. However, in some cases, they may be formed around organism activity.