Paleontology Presentation FOSSILS What are fossils Where are

Paleontology Presentation

FOSSILS What are fossils? Where are fossils found? How are fossils formed? What are the types of fossils? Do fossils tell us about our past?

What are fossils? • Fossils are preserved remains or traces of living things. • Latin meaning of fossil “to dig” • Fossils tell us not only when and where organisms once lived, but also how they lived. • Paleontologists – scientists who studies fossils.

Where are fossils found? ◊ Fossils are most often found in sedimentary rocks. Sedimentary rock is the type of rock that is made of hardened sediment (broken pieces of other rock). ◊ The heat and pressure involved in forming igneous and metamorphic rocks most often destroy fossil material.

How are fossils formed? Most fossils form when living thing die and are buried by sediments. The sediments slowly harden into rock and preserve the shapes of the organisms. Usually, the remains of dead plants and animals are quickly destroyed. Scavengers eat the dead organisms, or fungi and microorganisms cause them to decay Organisms have a better chance of being preserved if they have hard parts; i. e. bones, shells, teeth, seeds, and woody stems.

What are the types of fossils? Fossils found in rock include: petrified fossils, molds and casts, carbon films, and trace fossils. Other fossils form when the remains of organisms are preserved in substances such as tar, amber, or ice. Petrified fossils – minerals replace all or part of an organism. Molds – a hollow area in the shape of or part of an organism. Casts – a copy of the shape of the organism. Carbon films – an extremely thin coating of carbon on rock (sediment squeezes almost the entire decaying organism away). Trace fossils – provide evidence of the activities of living organisms. Ex. Fossilized footprints. Preserved remains – the entire organism remains with little or no change: preserved by tar, amber (sap or resin), or ice.

Do fossils tell us about our past? Change Over Time • Fossil record – provides evidence about the history of life on Earth. The fossil record also shows that different groups of organisms have changed over time. • Older rocks – contain fossils of simpler organisms. • Younger rocks – contain fossils of more complex organisms. • Scientific theory – well –tested concept that explains a wide range of observations. • Evolution – is the gradual change in living things over long periods of time. • Extinct – when an organism no longer exists anywhere on Earth.

Do fossils tell us about our past? Fossils and past Environments Fossils provide evidence of Earth’s past climate and environment. For example: coal has been found in Antarctica. Coal forms from plants in warm, swampy regions; therefore, that means that Antarctica was not always cold as it is today.

Formation of Kinds of Fossils Petrified fossils forms by replacement minerals in water that make a copy of the organism. The fossil formed when sediment covered the organism.

Molds & Casts Molds: forms when the hard part of the organism, such as a shell, is buried in sediment. The organism decays leaving a hollow mold in the shape of the object. Casts: forms if water deposits minerals and sediments into a mold. The sediments harden into the shape of the mold looking like the original organism.

“What are fossils? ” video clip

Molds & Casts

Would this be a cast fossil or a mold fossil?

Carbon films forms when sediment buries an organism, the weight of the sediment squeezes almost the entire decaying organism away leaving a carbon print of the organism.

Trace fossils forms when mud or sand that the animal stepped into eventually was buried by layers of sediments. Slowly the sediment became solid rock preserving the footprints for millions of years.

Trace Fossils

Preserved fossils Forms when entire organisms or parts of organisms are prevented from decaying by being trapped in rock, ice, tar, or amber. (Ex. Wooly mammoth trapped in ice)

Preserved remains

Ice Man discovery

1. A ______ fossil forms when minerals soak into the buried remains, replacing the remains, and changing them into stone A. Trace B. Cast C. Mold D. Carbon film E. Preserved F. Petrified `

2. A ______ fossil forms when the hard part of the organism, such as a shell, is buried in sediment and an imprint or cavity in the shape of the organism is left. A. Trace B. Cast C. Mold D. Carbon film E. Preserved F. Petrified

3. A ______ fossil forms when a mold is filled with sand or mud that hardens into the shape of the organism. A. Trace B. Cast C. Mold D. Carbon film E. Preserved F. Petrified

4. A ______ fossil forms when an entire organism or parts of the organism is prevented from decaying by being trapped in rock, ice, tar, or amber. A. Trace B. Cast C. Mold D. Carbon film E. Preserved F. Petrified

5. A ______ fossil forms when organisms or parts, like leaves, stems, flowers, fish are pressed between layers of soft mud or clay that harden squeezing almost all the decaying organism away leaving the carbon imprint in the rock. A. Trace B. Cast C. Mold D. Carbon film E. Preserved F. Petrified

6. A ______ fossil forms when the mud or sand hardens to stone where a footprint, trail, or burrow of an organism was left behind. (You can make inferences about the activity of the organism. ) A. Trace B. Cast C. Mold D. Carbon film E. Preserved F. Petrified