Earth Science Chapter 10 A Trip Through Geologic Time Section 1 Fossils

How do fossils form?

Most fossils form when living things die and are buried by sediments. The sediments slowly harden into rock and preserve the shapes of the organisms.

What are the different kinds of fossils?

Fossils found in rock include molds and casts, petrified fossils, carbon films, and trace fossils. Other fossils form when the remains of organisms are preserved in substances such as tar, amber, or ice.

What does the fossil record tell about organisms and environments of the past?

The fossil record provides evidence about the history of life and past environments on Earth. The fossil record also shows that different groups of organisms have changed over time.

What can fossils help scientists infer

how Earth's surface has changed. Fossils are clues to what past environments were like

Where do most fossils form?

Most fossils form from animals or plants that once lived in or near quiet water such as swamps, lakes, or shallow seas where sediments build up.

Why does only the hard part of an organism generally leave fossils?

When an organism dies, its soft parts often decay quicly or are eaten by animals. The hard parts include bones, shells, teeth, seeds, and woody stems.

For a fossil to form

the remains or traces of an organism must be protected from decay.

Most common fossils are

molds and casts.

Steps to becoming a fossil

>An animal dies and sinks into shallow water.
>Sediment covers the animal.
>The sediment becomes rock, preserving parts of the animal.
>Weathering and erosion eventually expose the fossil at the surface.

A mold is

a hollow area in sediment in the shape of an organism or part of an organism. A mold forms when the hard part of the organism, such as a shell, is buried in sediment.

A cast is a

solid copy of the shape of an organism.

Water carrying dissolbved minerals and dediment may seep into the empty space of a mold.

If the water deposits the minerals and sediment there, the resut is a cast.

What are three ways in which the remains of an organism can be preserved with little change?

The tree ways are Tar, Amber, and Freezing.

The fossil record

provides evedence about the history of life and past environments on Earth. The fossil record also shows that different groups of organisms have changed over time.

Why is the peleomastodon only known from its fossils?

because its extinct

What is a scientific theory?

well tested concept that explains a wide range of observations

What is a fossil?

The preserved remains or traces of an organism.

How does a fossil form?

Most fossils form when living things die and are buried by sediments. The sediments slowly harden into rock and preserve the shapes of the organisms.

Which parts of an organism are most likely to be preserved as fossils?

the hard part of an organism generally leave fossils
When an organism dies, its soft parts often decay quicly or are eaten by animals. The hard parts include bones, shells, teeth, seeds, and woody stems.

What are the five different types of fossils?

Molds and Casts, Petrified Fossils, Carbon Films, Trace Fossils, Preserved Remains

How does a carbon film fossil form?

when sediment buries a fossil, some of the materials that make up an organism evaporate or become gases. These gases escape from the sediment, leaving the carbon behind. Eventually only a thin layer of carbon remains and preserves the organism

How are petrified fossils similar to preserved remains? How are they different?

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What are two things that scientists can learn from the fossil record?

The fossil record provides evidence about the history of life and past environments on Earth. The fossil record also shows that different groups of organisms have changed over time.

What does the fossil record show about how life has changed over time?

The fossil record shows that life on Earth has evolved, or changed over time. Simple one-celled organisms have given rise to complex plants and animals.The fossil record show that organisms have evoloved and many have become extinct.