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Grade 8 Integrated Science Chapter 16 Lesson 1 on fossils. This lesson gives detail about fossil, how they form, and the different types. The purpose of this lesson is for students to understand …

Grade 8 Integrated Science Chapter 16 Lesson 1 on fossils. This lesson gives detail about fossil, how they form, and the different types. The purpose of this lesson is for students to understand fossil and how they give us a record of our planet's past. Students should know the different types of fossils by the end of the lesson.
*This outline follows the Chapter 16.1 presentation slides.

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  • 1. Chapter 16 Lesson 1: Fossils – p564-572 – page 1 Vocabulary  Fossil (565) – the preserved remains or evidence of ancient living things  Catastrophism (565) – the idea that conditions and organisms on Earth change in quick, violent events  Uniformitarianism (566) – a principle that states that geologic processes that occur today are similar to those that have occurred in the past  Carbon Film (568) – the fossilized carbon outline of an organism or part of an organism  Mold (569) – the impression in a rock left by an ancient organism  Cast (569) – a fossil copy of an organism made when a mold of the organism is filled with sediment of mineral deposits  Trace Fossil (569) – the preserved evidence of the activity of an organism  Paleontologist (570) – scientists who study fossils  Evidence of the Distant Past  Just like old photos, fossils provide us with clues about Earth’s past  Fossils are the preserved remain or evidence of ancient living things Catastrophism  Many fossils represent plants and animals that are _____________________  In the past many scientists believed that a single, sudden, catastrophic ________________ killed the organisms that become fossil  Catastrophism is the idea that conditions and organisms on Earth change in______________, violent events o These include large volcanic eruptions and widespread ____________________.  Scientists eventually __________________ with catastrophism because Earth’s history is full of violent events  Most people who supported catastrophism thought that Earth was only a ____________thousand years old  Uniformitarianism  In the 1700s, James ________________ rejected the idea of catastrophism  Hutton thought that the processes responsible for changing the _________________ could also shape Earth’s surface o For example, he thought that erosion caused by streams could also wear down ____________________________. o He realized that these processes would take a long ______________________, and proposed that Earth was much older than a few thousand years  Hutton’s ideas were eventually included in a principle called _____________________________________.
  • 2. Chapter 16 Lesson 1: Fossils – p564-572 – page 2 o The principle of uniformitarianism states that geological processes that occur ____________are similar to those that have occurred in the past o According to this view, Earth’s surface is constantly being reshaped in a steady, uniform manner  Today, uniformitarianism is the basis for understanding Earth’s past  But scientists also know that catastrophic event do ___________________________ occur o Huge volcanic eruptions and giant meteorite impacts can change Earth’s surface quickly and can be explained by natural processes Fossil Formation  Not all dead organisms become_____________________. More than likely, you will not become a fossil.  Fossils form only under _______________________ conditions. Conditions for Fossil Formation  Most plants and animals are eaten or ____________when they die, leaving no trace that they ever lived o Consider an apple. More than likely an apple will decay into a _____________lump and be decomposed by bacteria and insects.  Some conditions increase the chances that a fossil will form. 1. If the organism has __________parts, such as shells, teeth, or bones 2. If the organism is _______________quickly after it dies. o This way the layers of sand and mud slow or stop decay Fossils Come in All Sizes  Many of the fossils we think of are large dinosaur fossils.  However, not all fossils are large.  Microfossils are tiny fossils each about the size of a speck of ____________. o Details of microfossils can be seen only under a microscope Types of Preservation
  • 3. Chapter 16 Lesson 1: Fossils – p564-572 – page 3  Fossil are preserved in many different ways: o Preserved Remains o ___________________________________________ o Mineral Replacement o ______________________ o Casts o Trace Fossils Preserved Remains  Sometimes the _________________________ remains of organisms are preserved as fossils  For this to happen, an organism must be completely _________________________ in some material over a long period of time. o This would prevent it from being exposed to _________________ or bacteria o Generally these fossils are less than 10,000 years old. However insects preserved in ____________________ can be millions of years old. Carbon Films  Sometimes when an organism is buried, exposure to heat and pressure forces gases and _________________ out of the organism’s tissues.  This leaves only the ________________________ behind  A carbon film is the fossilized carbon outline of an organism or part of an organism Mineral Replacement  Replicas, or copies, of organisms can form from _____________________________ in groundwater.  They fill in the pore spaces or ______________________________ the tissues of dead organisms  Petrified wood is an example
  • 4. Chapter 16 Lesson 1: Fossils – p564-572 – page 4 Molds  Sometimes all that remains of an organism is its fossilized ________________ or impression.  A mold is the _________________________ in a rock left by an ancient organism o First, sediment must harden around a buried organism o As the organism ______________________ over time an impression of its shape remains in the sediment o Eventually the sediment turns into ___________________________. Casts  Sometimes, after a mold forms, it is filled with more __________________________________  A cast is a fossil copy of an organism made when a mold of the organism is filled with sediment or mineral deposits. Trace Fossils  Some animals leaves fossilized traces of their _______________________ or activity  A trace fossil is the preserved evidence of the activity of an organism  These include: o ___________________________ o Footprints o Nest o Droppings  These fossils help scientists learn about characteristics and _____________________ of animals  They can reveal clues about an organism’s _____________, speed, and whether they traveled ______________________ or in groups.
  • 5. Chapter 16 Lesson 1: Fossils – p564-572 – page 5 Ancient Environments  Scientists who study _________________________ are called paleontologists  Paleontologists use the principle of uniformitarianism to learn about ancient organisms and their _______________________________.  They often compare fossils of ancient organisms to organisms living ___________________________ o For example, trilobite fossil and ______________________________ crabs look alike o Horseshoe crabs today live in shallow water on the ocean floor o Partly because trilobite fossils look so much like horseshoe crabs, paleontologists __________________ that trilobites also lived in shallow ocean waters Shallow Seas  Today, Earth’s continents are mostly above ______________________________________.  But, sea level has ________________________ , flooding Earth’s continents, many times in the past  For example, a shallow ocean covered much of North America ___________________ million years ago.  Fossils of organisms that lived in that shallow ocean help scientists reconstruct what the _________________________ looked like at that time. Past Climates  Evidence indicates that Earth's present-day climate is ____________________________.  Fossils show that Earth's climate has warmed and ___________________________ many times in the past  ______________________ fossils are especially good indicators of climate change  For example, fossils of ferns and other tropical plants dating to the time of the dinosaurs reveal that Earth
  • 6. Chapter 16 Lesson 1: Fossils – p564-572 – page 6 was very warm 100 million years ago o Tropical forests and _____________________________ covered much of the land o Millions of year later, the swamps and forests were gone, but coarse _______________________ grew in their place o Huge sheets of ice called __________________________spread over parts of N. America, Europe, and Asia. o Fossils suggest that some species that lived during this time, such as the woolly mammoth were able to survive in the colder climate