U1 L2 and the History of

Lesson 2

Explore the skeletons of modern organisms along with fossils found in different strata to identify similarities and differences across organisms and make arguments based on evidence.

What do fossils reveal about the on ? Phenomenon: once roamed the Earth, but now we do not find them alive anywhere.

Dinosaurs are generally considered by scientists today as one of the more successful vertebrates to ever inhabit Earth. Why do you think that is? EX OPP: Research the factors that scientists use to determine dinosaurs to be more successful than other vertebrates.

Two common misconceptions are that dinosaurs and humans (cavemen) lived at the same time and that humans caused the extinction of the . Dinosaurs had already died off 65 million years before humans had made an appearance on Earth. However, small (including tiny primates) were alive at the time of the dinosaur. It’s a sunny day in Sheep Creek, Wyoming. This young scientist Introduction 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? 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 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 are descended from dinosaurs and that whales are descended from mammals with legs? Throughout this lesson, you will identify patterns in the 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 P26-27 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 once living organism. There are two main types of fossils 1) body fossils 2) trace fossils. 1. Fossils and the Fossil Record P26-27 Body Fossils Trace Fossils Preserve the traces that living things left Formed when the bodies or body parts of behind. organisms are preserved as fossils. Include things like footprints, animal burrows, Provide direct evidence of formerly living toothmarks, and feces. things. Provide indirect evidence of formerly living things.

Both can provide a lot of information about how organisms lived. Ex: • Footprints can show how fast an animal walked or ran. • The fossil nests left by certain dinosaurs provide evidence that dinosaurs cared for their young, similar to the way birds do today. 1. Fossils and the Fossil Record P26-27 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. Add to bottom of notes page (space)Steps: How fossils form 1. Fossils and the Fossil Record P26-27 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. Add to bottom of notes page (space)Steps: How fossils form 1. Fossils and the Fossil Record P26-27 Unusual type of body fossil is produced when, in certain rare cases, an entire organism is preserved.

Amber Ice 1. Fossils and the Fossil Record P26-27 Earth’s fossils can be placed along a timeline using absolute and relative dating, techniques. The fossil record describes the history of life on Earth as documented by the fossils collected so far. Shows that there have been many changes in the kinds of organisms living on Earth over time. Fossil record does not include every species that has ever lived on Earth. Very few living things actually end up as fossils. 1. Fossils and the Fossil Record Review 2. Order the steps of fossilization from 1 to 5. 1. Match each fossil with its type 3 Layers of sediment cover the bones. Erosion removes rock layers and reveals 5 the fossil. 2 The soft parts of the body rot away. Pressure turns the sediments into rock. The bones slowly decay are and 4 replaced by minerals. 1 An animal dies. 3. Does the fossil record include every species that every lived? Why or why not? No, very few living things actually end up as fossils. Most dead organisms are eaten or decompose before they have a chance to be preserved. Also, some animals without hard body parts might not be preserved at all. 2. Increasing Complexity in the History of Life You and your shoulder partner, Read and take your own notes of Sec 2 P28 When finished do review Then Read Sec 3-4 p29-31 2. Increasing Complexity in the History of Life

Earth’s oldest fossils are about 3.7 billion years old. single “simple” cell → complex cells were much larger/had a nucleus → Multicellular Life

Increasing complexity is one pattern in the history of life. The fossil record shows that the earliest life forms had a single, simple cell. Over time, more complex cells appeared, followed by multicellular life. However, simple organisms still exist today and are both abundant and successful. The increasing complexity of life over time.

Bacterial Cell → Cell with a nucleus →

No, there are many "simple" organisms still alive today.

INVESTIGATION 1 INTERPRETING FOSSILS Scientists have found fossils, like these, How do we know that dinosaurs once of organisms that look different from existed? organisms that are alive today. INVESTIGATION 1 INTERPRETING FOSSILS 1) What do you think you can tell about an organism or its environment from fossilized bones? You can often tell many things about an organism from its fossils, like its general structure and size. Depending on the parts you find, you might also be able to tell what it ate, how it moved, how it reproduced, where it lived, how it interacted with other organisms.

You would not be able to tell what it What can you not tell? sounded like. And, in general, you might not be able to tell much about its soft body parts, its color, or its daily behaviors. INVESTIGATION 1 INTERPRETING FOSSILS In this activity you are going to draw conclusions about modern- day organisms and their environment based on their skeletons. In pairs you will: Analyze skeletons of modern-day organisms. Work in pairs and pick up Handout A. Use logic to develop explanations about each organism and its environment. INVESTIGATION 1 INTERPRETING FOSSILS Now, you will use the same skills you just used in the previous activity to draw conclusions about fossilized organisms and their environment. In general, assumes that the same skills you use to understand organisms now can be used to understand organisms that lived in the past because the assumption is that natural laws operate today as in the past. INVESTIGATION 1 INTERPRETING FOSSILS Now, you will use the same skills you just used in the previous activity to draw conclusions about fossilized organisms and their environment. Analyze fossils of ancient organisms. Visit each station in the room and analyze each fossilized organism from Handout B. Use logic to develop explanations about each organism and its environment. Record all the information in your notebook. INVESTIGATION 1 INTERPRETING FOSSILS

Wrap Up 3. Why are you more likely to find fossils of organisms that lived in than land-based organisms? Fossils are formed in sedimentary rock which develops only near water. 4. What can you tell about an organism or its environment based on its fossilized remains? You can tell its size, general shape, the type of environment it might have lived in, and what kind of food it ate. 5. What can you NOT tell about an organism or its environment based on its fossilized remains? You cannot tell the noises that it makes or its smell.

3. Increases in the Diversity of Life At times in Earth’s history, biodiversity on Earth increased suddenly. One example of this was during the Explosion. In this photo, scientists are excavating fossils from the time of the .

Rock strata from the time of the Cambrian Explosion provide fossil evidence of the origin of most of the major groups of animals found on Earth today. 3. Increases in the Diversity of Life

The term biodiversity describes the variety of species on Earth. scientists have observed a sudden, rapid increase in biodiversity. adaptive radiation— “adaptive” because the new species are well suited to living in their environments “radiation” because many species appear quickly, as if spreading out from a single point. 3. Increases in the Diversity of Life The Cambrian Explosion most likely resulted from a combination of factors. 1) changes in the made more habitats available at that time. 2) increasing oxygen levels in the atmosphere may have allowed for more active, complex organisms to live. 3) key features of living things themselves may have contributed to the explosion. Vision, Shells, other hard body parts Some scientists think that animals first developed vision, the ability to see, at this time. Another possibility is that shells or other hard body parts originated at this time. 4. Decreases in the Diversity of Life Scientists use patterns in the fossil record to make conclusions about life on Earth. What do you notice about this illustration? Different fossils are found in different strata of rock. What happened at the blue line? Some fossils don’t seem to appear again after the blue line. A new fossil appears after the blue line. What do you think happened to organisms whose fossils never show up again in the fossil record? 4. Decreases in the Diversity of Life A species becomes extinct when all members of the species die and the species no longer exists. Scientists conclude that a fossil species is extinct when it vanishes from the rock strata—no more fossils are found after a certain time. Extinction is a normal event in the history of life, and the fossil record provides evidence of many species’ extinctions in Earth’s history. 4. Decreases in the Diversity of Life Sometimes, however, many species go extinct suddenly. A mass extinction is an event in the history of life on Earth in which a large number of species go extinct over a relatively short time period. Note, though, that “relatively short” on a geological time scale can mean millions of years. A mass extinction is an example of a pattern that is seen multiple times in Earth’s history. 4. Decreases in the Diversity of Life

Scientists believe that there have been five mass extinction events, based on fossil data. Where are the five mass extinction events on this graph? How do you know? When the total number of organisms drops suddenly, this indicates a mass extinction event. Look for the troughs in the graph. 4. Decreases in the Diversity of Life

This graph shows the total number of different marine fossils found from each time period. The number of marine organisms is a good measure of diversity because most fossils are of organisms that lived in or near water. 4. Decreases in the Diversity of Life The first mass extinction in Earth’s history occurred at the end of the Ordovician Period and was probably the result of an extreme ice age. During the ice age, a huge ice sheet formed over Earth. As more and more water froze to ice, less water was available to fill the oceans. Sea levels dropped, and countless marine habitats were destroyed. About 85 percent of marine life was wiped out at this time. 4. Decreases in the Diversity of Life The Permian extinction was the largest extinction in the . About 90 percent of Earth’s species died out during this time. Some scientists think the Permian extinction was related to huge volcanic eruptions in what is now Siberia. These eruptions produced enough lava to cover an area the size of the continental United States in a layer a kilometer deep. The eruptions likely released greenhouse gases that led to extreme global warming. Water flow in the oceans was also disrupted, resulting in very low oxygen levels there. 4. Decreases in the Diversity of Life The Cretaceous mass extinction, famous for the extinction of many dinosaurs, appears to be linked to a meteorite impact. Scientific evidence shows that, at the end of the Cretaceous, a meteor about 10 kilometers across struck what is now the Yucatán Peninsula in Mexico. A large crater has been found in this location. Scientists think that the collision caused firestorms on land and produced airborne debris that blocked the sun for a year or more. The lack of sunlight would have killed first, and then the animals that eat them. Volcanic activity near the end of the Cretaceous may also have contributed to the mass extinction. The Cretaceous extinction did make room for other species, though. Some mammals, birds, and other species survived, changed, and increased in diversity. 4. Decreases in the Diversity of Life

One pattern you can see in this graph is that each mass extinction is followed by adaptive radiations in which biodiversity increases again.

The most likely explanation for this pattern is that the extinction of a large number of species opens new opportunities for the species that survive, which then increase in diversity. https://video.wtvp.org/video/nova-making-north-america-life/

Identify patterns in the fossil record that lead to conclusions about mass extinction events, adaptive radiation events, and changes in types of organisms over time. INVESTIGATION 2 FINDING PATTERNS IN FOSSIL DATA

In pairs you will: Read about the dinosaur fossil record. Read Handout C. Decide what you think happened to the dinosaurs based on the data.

Map the five mass extinction events. Analyze the data on Handout D. Label where you think the five mass extinction events are indicated. INVESTIGATION 2 FINDING PATTERNS IN FOSSIL DATA In pairs you will: Compare fossils to modern day organisms. Analyze the fossils on Handout E. Compare them to modern day organisms. Fill in data table Compare fossils to each other. Analyze the fossils on Handout F. Compare them to each other. Answer 9-12 INVESTIGATION 2 FINDING PATTERNS IN FOSSIL DATA Wrap Up What can you learn from comparing fossils to modern-day organisms? Since you can know more about the specific structures and behaviors of living organisms, you can draw some conclusions about how similar ancient organisms lived. What can you learn from comparing fossils found in different strata (from different periods of time on Earth) to each other? By comparing fossils from different periods of time, you can see how life on Earth changed over time. You can see how the complexity of traits has increased in living things over the span of life's existence on Earth. What patterns can you find by looking at the whole fossil record of organisms over the history of Earth? You can see mass extinction events and the how organisms changed throughout history.

5. Changes in Life Forms Over Time Birds in the Fossil Record

A pattern you see is that the fossil record provides evidence that living things change over time.

Other, smaller, patterns in the fossil record can also be found by comparing fossils to modern day organisms or to each other.

Fossils also show how the ancestors of birds changed over time.

Archaeopteryx fossils provide evidence that birds are related to dinosaurs. 5. Changes in Life Forms Over Time Birds in the Fossil Record Archaeopteryx is an intermediate form between earlier life forms and modern-day life forms.

Archaeopteryx’s Archaeopteryx skeleton has some resembles those features of dromaeosaur characteristic of dinosaurs: modern birds: • Teeth • Wings • three claws on • Feathers their front • wishbone, a limbs bone related • long bony tails to flight.

https://www.youtube.com/watch?v=eaWb0UUNc00 5. Changes in Life Forms Over Time Whales in the Fossil Record

The fossil whale relatives over about 50 million years, whales entered the oceans and whale species became better and better suited to aquatic life. 5. Changes in Life Forms Over Time Whales in the Fossil Record The fossil Ambulocetus is called the “walking whale whale” because it had large hind relatives over legs that were used both for about 50 walking on land and swimming in million years, water. whales The legs of Ambulocetus end in hooves, providing evidence that entered the whales are descended from hoofed oceans and mammals. whale species became better Although Pakicetus looks nothing and better like today’s whales, scientists know suited to that it was a whale because of aquatic life. certain features of its skull. Pakicetus was the size of a wolf and had four long legs. It ate meat and fish and lived mainly on land. 5. Changes in Life Forms Over Time Whales in the Fossil Record The fossil whale relatives over about 50 million years, Fossils show fin-like front whales limbs, small hind limbs, and a streamlined body suitable for entered the swimming. oceans and These changes over time made whale species whales better and better became better suited to life in the water. and better suited to aquatic life. 5. Changes in Life Forms Over Time Whales in the Fossil Record The fossil whale relatives over Whales became larger and about 50 also better suited to living million years, in water. whales entered the oceans and whale species became better and better suited to aquatic life. https://www.youtube.com/watch?v=_OSRKtT_9vw

https://ocean.si.edu/through-time/ancient-seas/evolution- whales-animation 5. Changes in Life Forms Over Time Whales in the Fossil Record

40 mya Basilosaurus The tiny bones are Unused not involved in the Structures whale’s movement – unused structures

Present day - Whale

The modern whale appears to be best adapted for swimming long distances under water because it has large fins to swim fast and large lungs so it can hold its breath underwater for a long time

6. Scanning and Printing Fossils p36-37

Fossils are often rare and scientifically valuable. Scientists are developing new ways to study fossils that will not damage them. An engineering solution for studying rare, important fossils should meet certain criteria and satisfy certain constraints. The criteria are the requirements that must be met for an engineering solution to be considered successful. The constraints are limitations on an engineering solution. The more precisely a design task’s criteria and constraints can be defined, the more likely it is that the designed solution will be successful. 6. Scanning and Printing Fossils p36-37 Fossils are often rare and scientifically valuable. Scientists are developing new ways to study fossils that will not damage them. An engineering solution for studying rare, important fossils should meet certain criteria and satisfy certain constraints. Criteria for Studying Fossils Constraints for Studying Fossils Scientists should be able to study Must be cost effective. the fossil without damaging it Scientists should be able to obtain as much information from a fossil as must be safe for the people involved possible, including, in some cases, as well as for the environment. information from the fossil’s internal structure. Many people should be able to look at important fossils. https://www.youtube.com/watch?v=YCdIiVpUF6E 6. Scanning and Printing Fossils p36-37 https://www.youtube.com/watch?v=S9AI_CJyA50 An engineering solution that satisfies the criteria and constraints of this problem is to create a detailed copy of the fossil, leaving the real fossil intact.

A fossil is scanned with a device called a computed tomography scanner, or CT scanner. Used to create detailed images of the internal and external structure of a fossil. This can be done without cutting the fossil open or damaging it.

The CT images are sent to a computer and printed using a 3-D printer. 3-D printers build three-dimensional objects from bottom to top, adding thin layers one at a time. Different materials can be used for 3-D printing, including plastic, wax, and metal.

Put your answers to each response on the left