Last updated: August 16, 2022
Lesson Plan
So You Wanna Be a Paleobotanist?
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- Grade Level:
- Upper Elementary: Third Grade through Fifth Grade
- Subject:
- Science
- Lesson Duration:
- 60 Minutes
- State Standards:
- Colorado Standards in Science: 4th grade; 2.2.a – Explain what fossils say, the similarities between fossil and living organisms. 2.2.b – Interpret evidence for past environments. 2.3.c – Compare and contrast different habitat types.
- Additional Standards:
- 5th grade; 3.2.a – Analyze and interpret data identifying ways climate can change Earth’s surface. 3.2.b – Develop and communicate an explanation on how climate can change Earth’s surface.
- Thinking Skills:
- Applying: Apply an abstract idea in a concrete situation to solve a problem or relate it to a prior experience. Analyzing: Break down a concept or idea into parts and show the relationships among the parts. Evaluating: Make informed judgements about the value of ideas or materials. Use standards and criteria to support opinions and views.
Essential Question
How do we know what prehistoric environments were like?
Objective
Students will learn scientific methods used to reconstruct paleoclimatic conditions. They will also learn how to identify plants using a dichotomous key. Lastly, students will be able to compare past and present climate at Florissant.
Background
Part One: Leaf Identification Activity
Paleontologists and/or paleobotanists use several methods to reconstruct paleoclimatic conditions. Fossils are the clues that paleontologists and paleobotanists use to find out information about the very distant past. Fossils are incredibly important in the reconstruction of paleoclimatic conditions as each species is adapted to different habitats and environments, so knowing what lived in an area can provide scientists with clues about what the past conditions of the studied area used to be like. For example, a fossil fish is a clue that the area was covered with water. Fossil plants are incredibly useful for reconstructing paleoclimatic conditions because most extinct species have living relatives that presumably exist in similar conditions.
Fossil plants are also useful because while animals can move around from place to place, plants are stuck in the environment in which they take root. Therefore, studying fossil plants to reconstruct paleoclimatic conditions is far more representative of a local environment than studying climatic conditions that prehistoric animals lived in.
Part Two: Plant Data and Climate Analysis
Different species of trees require different conditions in order to survive and grow. Ask students to suggest some ideas for types of growing conditions (e.g., type of soil, temperature, amount of water, sunlight, etc.) Explain that for today, we will focus on two conditions: temperature and precipitation. Note that we will be using averages over the course of a year, not the weather on any given day.
How do we know what conditions a tree needed in order to survive if the tree lived 34 million years ago and is now a fossil? Remind students that all of these fossils have distant living relatives - very similar trees that are still living today, although they are not necessarily found in the same locations. For example, fossil redwood trees are closely related to the coastal redwood trees in California today. We will assume that the fossil species needed the same growing conditions as their living relatives.
Published studies have used a variety of methods to analyze the fossil plant community of Florissant Fossil Beds National Monument, and all have concluded that the climate 34 million years ago was much warmer and wetter than it is today. For comparison, the climate of Florissant today has an average annual temperature of 39.5° F (about 4° C) and an average annual precipitation of about 17 inches (430 mm). Published studies of the ancient climate, using the same method as in this lesson, estimated an average annual temperature of 55-59° F (13-15° C) and an average annual precipitation of 20-31.5 inches (500-800 mm) of rainfall per year. Studies using other methods, such as leaf morphology or fossil pollen, have come to slightly different but generally similar conclusions, estimating temperatures of 55-64°F (13-18°C). So, the general scientific consensus is that the climate of Florissant was far warmer and wetter 34 million years ago than it is today.
Preparation
You will need:
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Pictures of fossil plants
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Dichotomous key
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Growing condition data strips
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Pencil
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Paper
Materials
A document with pictures of fossil leaves from Ancient Florissant valley for you to identify. Cut out the data strips to use in the second part of the activity.
Download Fossil Leaf Images and Data Strips
A copy of the leaf dichotomous key for you to identify the different fossil leaves found in Florissant Fossil Beds. See the video on our webpage linked below for an example of how to use it.
A key to help you check your identifications of your fossil leaves.
Download Fossil Leaf Identification Key
Lesson Hook/Preview
Paleontologists and paleobotanists use a few methods to reconstruct past climates. Fossils provide the clues we need to learn about the distant past. Fossils are extremely important in reconstructing the conditions of the paleoclimate because each species is adapted to a particular habitat and environment. This means that knowing what things lived in an area can give scientists clues about the past climate of the studied area. For example, if a fossil fish is found it tells us that the area was once covered by water.
Procedure
#1: Pick at least 5 fossil leaves to identify. If you choose to identify more, the stronger your data will be later to determine the climate.
Fossil plants are especially helpful in reconstructing paleoclimate conditions. This is partly because most extinct plant species have living relatives that are thought to live in similar habitats today. Also, unlike animals, plants are stuck in the area where they are rooted and cannot move around from place to place. This means that studying plant fossils to reconstruct the past climate is more representative of the local environment rather than studying prehistoric animals that could have moved.
#2: Use the dichotomous key to identify the leaves you picked one at time. Start at page 1 and pick which of the two options best describes the leaf you are looking at. When you pick an option, turn to the page it tells you and make your next choice. Keep going until you get to the plant's identity. (Watch the video below to see our intern walk you through identifying one leaf.) Repeat this until you identify all your leaves.
Different species of trees need different conditions to live and grow. What are some factors that could affect how well a tree grows? Some conditions include soil type, temperature, sunlight, and amount of water.
In this activity we will be looking at the annual averages of temperature and precipitation. You will be using the conditions needed by the plants you have identified to reconstruct the paleoclimate they all once lived in.
#3: Pick out the data strips for each of the plants you identified.
Each strip has the plant name, temperature, and precipitation data. The yellow outlined box on each thermometer and rain gauge shows the range of temperature and precipitation the plant can live in.
#4: Place the strips side by side on a table so that the thermometers are all at the same height. Figure out which is the lowest high temperature (the coldest of the warm temperatures shown by the top of the box on each thermometer) out of the group and write it down. This is the highest temperature at which all the plants can grow. Write this temperature down.
#5: Find the highest low temperature (the warmest of the cold temperatures shown by the bottom of the yellow box) and write this temperature down too. This is the lowest temperature at which all the plants can grow.
These two temperatures you have written down tell you the range at which all these plants could survive.
#6: Repeat steps four and five to find the lowest high and highest low levels of precipitation with the rain gauges. This will show you the range of precipitation levels all your plants can live in. Write this range down as well.
A number of studies by scientists used a variety of methods to analyze the plant fossils from Florissant Fossil Beds National Monument. These studies have found that the climate of the Florissant valley 34 million years ago was much wetter and warmer than today.
Today, Florissant has an average temperature of 39.5°F and an average annual precipitation rate of about 17 inches. Scientists who used the same method you did estimated an average annual temperature range of 55°F to 59°F and an average annual precipitation range of 20 to 31.5 inches.
Other studies that used different methods such as leaf morphology have some to slightly different, but similar conclusions. Their results estimated past temperatures of 55°F to 64°F. This is still warmer than temperatures today, so the general agreement that Florissant's Eocene climate was much warmer and wetter than today.
Vocabulary
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Paleobotany: noun; the study of fossil plants
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Paleoclimate: noun; a past climate that existed in an area during a particular time in the geologic past
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Precipitation: noun; water or the amount of water that falls to the earth as hail, mist, rain, sleet, or snow
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Paleontologist: noun; a specialist in paleontology
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Dichotomy: noun; a division into or distinction between two groups that differ greatly
Assessment Materials
ReflectionWere the growing conditions in Florissant, CO the same 34 million years ago as they are in the same spot today? Was it warmer or colder in the past? Wetter or drier? By how much? Remind the students of the average temperature and precipitation ranges of Florissant today.
Would comparing data from all 9 fossils, instead of just 5, make you more confident of your results? Would it help narrow down the ranges of possible temperatures even further? Point out that scientific studies usually use several dozen species. Would it help to use 50 or 100 species? Why?
Restate the conclusions of professional paleontologists at Florissant Fossil Beds National Monument (see background information, above). Were your answers similar?
Rubric/Answer Key
It was fairly warmer in Florissant Valley 34 million years ago and there was a lot more rain every year.
It would help to use all 9 fossils or 100 species because the more data you use, the more accurate and narrowed down the results will be.
Additional Resources
Check out our So You Wanna Be a Paleobotanist activity webpage for step by step instructions with pictures!