Adaptations L2S1

​Learning Objective:

​MS-LS4-1 Analyze and interpret data for patterns in the fossil record that document the existence, diversity, extinction, and change of life forms throughout the history of life on Earth under the assumption that natural laws operate today as in the past.

​A look at the vocabulary for this lesson.

1. ​fossil record-the history of life on Earth as documented by the fossils collected so far

2. fossil-the preserved remains or traces of a once-living organism

3. biodiversity-the variety of species on Earth

4. extinct-when all members of a species die and the species no longer exists

5. mass extinction-an event in the history of life on Earth in which a large number of species go extinct over a relatively short time period

6. criteria-the requirements that must be met for an engineering solution to be considered successful

7. constraints-the limitations on an engineering solution

​Fossils and the History of Life

What do fossils reveal about the history of life on Earth?

​It’s a sunny day in Sheep Creek, Wyoming. This young scientist is brushing away 150 million-year-old rock fragments, carefully digging out the tail bones of an enormous dinosaur called Diplodocus. Besides bones, dinosaurs have also left behind footprints, eggs, and even lumps of preserved feces! But what can scientists learn from fossils?

Open Ended

Name something that you think scientists can learn from fossils?

​Fossils tell the story of life on Earth. For example, fossils can reveal how the number of living things on Earth has changed over time. You will learn about times when many new kinds of living things originated relatively quickly, as well as about huge mass extinctions in which many living things died out suddenly. What could have caused such massive die-offs? You will then look at how specific groups of living things changed over time. For example, what evidence is there that birds are descended from dinosaurs and that whales are descended from mammals with legs?

​Throughout this lesson, you will identify patterns in the fossil record by looking at charts, graphs, and images. You will learn a lot about how life appeared, changed, and disappeared. Finally, because many fossils are rare and scientifically valuable, you will learn how scientists are creating detailed copies of important fossils so that they can be more easily studied.

​1. Fossils and the Fossil Record

​ While walking on the beach one day, you leave a footprint in the sand. How long will the footprint last? An hour? A day? Could your footprint become a fossil and last for millions of years?

Scientists learn about the organisms that once lived on Earth from the fossils they leave behind. A fossil is the preserved remains or traces of a onceliving organism.

Multiple Choice

What is a fossil?

• the preserved remains or traces of a once-living organism

• the variety of species on Earth

• the history of life on Earth as documented by the fossils collected so far

Multiple Select

What are the two main types of fossils?

• molecular fossils

• body fossils

• carbon fossils

• Trace fossils

Multiple Choice

body fossils are formed when the bodies or body parts of organisms are preserved as fossils.

• True

• false

Multiple Select

Trace fossils include things like

• footprints

• animal burrows

• toothmarks

• feces

​Fossils form in different ways. Consider mold fossils, one type of body fossil. A mold fossil is produced when an organism’s body leaves an imprint in sediment that hardens into stone. One of the photos in this section shows a mold fossil of a fern. If the mold is later filled in with a different material, this results in a cast fossil. Unlike mold fossils, a cast fossil has the same shape as the original organism.

​Body parts or whole bodies can also be preserved as fossils. The soft parts of living things typically decay quickly, so preserved body parts are often hard parts such as bones, teeth, or shells. Sometimes, minerals from groundwater slowly seep into the original bones or shells, replacing the original material and leaving a fossil made of stone, as in the dinosaur fossil shown in this section.

​An example of this process is shown in Figure 1. After a dinosaur dies, the soft parts of its body decay and layers of sediment cover the remains. Over time, pressure turns the sediments into rock. Groundwater seeps into the bones and replaces the original material with minerals. Finally, erosion removes some of the rock layers covering the bones. The fossil can now be discovered.

​Fossils can form in many different ways. In this example, the remains of a dead Diplodocus dinosaur turn into a fossil after being buried under layers of sediment. The fossil remains buried for a long time, until it is revealed by erosion.

​An unusual type of body fossil is produced when, in certain rare cases, an entire organism is preserved. Insects, for example, may be trapped in sticky plant resin that hardens into a material called amber. Fossils contained in amber may be preserved in incredible detail, as you can see in the photo. Entire organisms may also be frozen in ice. Several woolly mammoths have been preserved this way.

Open Ended

Name two ways that organisms may be preserved in whole and in great detail.

​Earth’s fossils can be placed along a timeline using absolute and relative dating, techniques you learned about in the previous lesson. Together, these fossils make up the fossil record. The fossil record describes the history of life on Earth as documented by the fossils collected so far. A look at the fossil record shows that there have been many changes in the kinds of organisms living on Earth over time. But does the fossil record provide a complete history of life on Earth?

Poll

Does the fossil record provide a complete history of life on Earth?

• Yes

• No

Multiple Choice

the process of determining whether one rock, fossil, or event is older or younger than another

• relative dating

• absolute dating

Multiple Choice

the process of determining the approximate age of a rock, fossil, or event

• absolute dating

• relative dating

​Unfortunately, the fossil record does not include every species that has ever lived on Earth. This is because very few living things actually end up as fossils. Most dead organisms are eaten or decompose before they have a chance to be preserved. In addition, many living things do not have the hard parts—such as bones or shells—that are most likely to be preserved. Even once a fossil is formed, only the right circumstances will result in its discovery. Nevertheless, the fossil record contains a huge amount of information about the history of life on Earth. In the next sections, you will take a journey through Earth’s rock strata and look at some of this history.

​Complete Question in your TCI Book Adaptation Lesson 2 Section 1

​Question 3 MUST use RACE Strategy

• Restate question

• Answer in your own words

• Cite text to support your answer

• Explain