History of Life on Earth Review

History of Life on Earth Review

Unit 9, TSWs 1-4

TSW 1 - Different ways fossils can form

TSW 2 - The Geologic Timescale as a way to organise Earth's history

TSW 3 - Evidence from the fossil record for Earth's history

TSW 4 - Evidence from the fossil record for organism's history

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​Content Overview

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Different types of fossils review

Answer the questions to see what you remember about the different ways fossils can form

Multiple Choice

This fossil is formed when an organism's tissues are replaced by minerals from water

• Amber fossil

• Cast and mold fossil

• Cast fossil

• Permineralized (replacement) fossil

Multiple Choice

This fossil was formed when the impression made by a shell in some sand hardened over millions of years. What is it?

• P

• Cast fossil

• Mold fossil

• Old fossil

Multiple Choice

How does this fossil form?

• The mosquito got stuck in tree sap. It hardened over many years.

• The mosquito was frozen in ice.

• The mosquito died and was quickly buried by sediment

• THe mosquito fell into a pit of sticky black mud(tar)

How do we learn about ancient life?

• ​​Paleontologists look for clues to understand what happened in the past

• Fossils of single celled organisms date back as far as 3.8 billion years.

• A fossil is a trace or imprint of a living thing that is preserved by geologic processes

• When an ​organism is trapped in mud or sediment, the resulting fossil becomes part of that sedimentary layer of rock

Life Science

Paleontologists are people who study fossils!

The Fossil Record

• All the fossils that have been discovered worldwide make up the fossil record.

• The fossil record gives evidence of many of the different organisms that have lived during Earth's long history.

• Each fossil gives information about a single organism.

• But overall, it helps us to understand larger patterns of change.

Subject | Subject

Some text here about the topic of discussion

What can we learn from fossils?

TSWs 3 and 4

• Information about the history of earth

• Information about the history of organisms​

​The fossil record provides us clues about the organisms that were alive in the past

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Layers of rock where there are no fossils provide evidence of mass extinctions​

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Mass extinctions

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The fossil record also provide evidence of the types of plants, climate and oxygen in the atmosphere.​

Earth's living conditions

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Fossils can tell us about how Earth has changed...

Multiple Choice

What might finding a high density of marine(sea) fossils and no fossils from the land tell you about a period of Earth's history

• There were no organisms living in the sea

• Earth's organisms were spread evenly through the land and sea

• Most of Earth's organisms lived in the sea

• Earth's organisms must have come from space

Multiple Choice

Finding lots of fossilised conifer trees might suggest what about a period of Earth's history?

• The climate of this location was probably hot and humid

• The climate of this location was probably cool

• The animals from this period did not eat conifers

• All trees on Earth must have been conifers

The fossil record also gives us clues about ancient animal behaviour

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Trace fossils can provide clues about family behaviours and courtship behaviours.

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For example, fossilised nests show us that adult dinosaurs would have cared for their young​

Organism's behaviours

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Fossils can also tell us about organisms ...

How organisms have changed

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Over many generations organisms change (evolve)

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Fossils can show how organisms have changed into what we see today, for example dinosaurs --> birds​

Multiple Choice

What does finding multiple fossils of the same species all in one location suggest about that organism?

• They probably all died due to too much competition

• They probably had a huge fight

• They probably lived alone

• They probably all lived together in a group (herd)

The Geologic Timescale (GTS)

​To keep track of Earth's long history, scientists have developed the geologic time scale.

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The geologic time scale is the standard method used to divide Earth's long 4.6-billion-year natural history into manageable parts.

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A tool organise to Earth's history.

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Right now, we are in the Holocene epoch of the Quaternary period (some scientists argue humans have created a new epoch by changing Earth - this is called the Anthropocene epoch but is not officially recognised yet

Was developed using the fossil record

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Earth's history is split into eons, eras, periods and epochs

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Each division represents a large-scale change in Earth's conditions​

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You will be required to describe the conditions and organisms present in one of Earth's periods in your quiz on Friday!!!!!

​GTS continued

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Multiple Choice

Which division of Earth's history is largest?

• Era

• Eon

• Epoch

• Period

Multiple Choice

Which three periods make up the mesozoic era

• Period 1, period 2, period 3

• Cambrian, Devonian, Permian

• Cretaceous, Jurassic, Triassic

• Holocene, Pleistocene, Pliocene

Paleontologists used relative and absolute dating to estimate the age of fossils

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Index fossils are widespread fossils that only existed on Earth for a short period of time​

If you find an index fossil in a new location, you can confidently age that layer of rock or fossil and then use relative dating to estimate the ages of layers above and below that layer

​How we know this

Multiple Choice

Which fossil is oldest?

• trilobite

• gastropod

• coral

• crinoid

Multiple Choice

Which fossil is youngest?

• trilobite

• coral

• fern

• ammonite

Multiple Select

What do paleontologists use to estimate the age of these layers of rock

• the law of superposition

• relative dating

• absolute dating

• radiometric dating

Open Ended

Explain the difference between relative dating and absolute dating(radiometric dating). What type of rock can be used for absolute dating?