Changes to Life Over Time 7.5.2 Changes to Life Over Time

Earth has not always been the way it is today Earth has not always been the way it is today. It gradually changes over time. What evidence do we have that proves the earth has changed? How long does it take for the earth to change? Will the earth change again like it did in the past?

Plants and animals on Earth have not always been like they are today Plants and animals on Earth have not always been like they are today. They have gradually changed over time. How do we know this? What is our evidence?

The Fossil Record This is a trilobite fossil. Have you ever seen a trilobite in a zoo? Do you see animals today that look like this? What kind of animal do you think this is?

Paleontology: the study of fossilized animals and plants Fossils are important evidence to support the theory of evolution. They show us how plants and animals have changed over time. Fossils are preserved remains of animals, plants and other organisms from the distant past. Fossils usually only contain the hard parts of an organism like bones and teeth. Sometime fossils can be footprints, droppings (coprolite), eggs, and other impressions. Amber is a fossil that is made from tree sap that may contain entire organisms that are perfectly preserved.

FOSSILS... Trilobites Ferns Brachiopods

Amber fossil Coprolite, fossilized poo Ammonites

Did they all live at the same time? When did they live? How long ago? Did they all live at the same time?

Animals of the Past: Patterns in the Fossil Record Notice the origins… Notice the time…

How much is ONE mya? What’s “65 mya” ? 65 millions of years ago How much is 65 mya? How much is ONE mya? How many human lifetimes is this? LET’S WORK IT OUT….

When you shrink 10 years of your life into one tiny millimeter…

a million years equals a football field!

You can plot 100s of millions of years on a map of your local area… 50 million years would be about 3 miles away (Walmart) 500 million years would only be about 30 miles away (Farmington)

…or plot billions of years within your state the past 500 million years the past 4.6 billion years

Now, when you see the 10s of millions of years that separate the origins of the different classes of vertebrates,

you will have a much better sense of the vastness of that time.

Transitions from pre-whales to whales… with hippos as their closest living cousins!

How has the horse evolved over time?

Evidence of the evolution of horses:    

Horse evolution The oldest fossils show that the first horses were as small as a fox and had four long toes and lived in marshes and wetlands. Through time the climate got drier, and the horses changed to adapt. They got taller so they could see predators over the tall grass they fed on. They evolved a single, large toe which became a hoof, which helped them run faster to escape predators. Their molars became longer and covered with cement, which helped them chew grass.

Whales used to walk on land, then they evolved to live in the sea.

Plants evolved, too, from an aquatic green alga protist. Their adaptations such as vascular tissue, seeds, and flowers helped them live and reproduce better on land.

Big Idea: The fossil record shows patterns that life has changed throughout Earth’s history.