14. What does the mammoth fossil tell
us about past climates in Illinois?
CLAIM:
EVIDENCE:
REASONING: Mammoths have physical features of
animals adapted to colder
environments, so the fossil mammoth
found in Illinois sediments tell us that
Illinois was colder 10,000 years ago.
Illinois had a colder climate in the past
10,000 year old mammoth fossils
25. What do the coral fossils tell us
about past environments in Illinois?
CLAIM:
EVIDENCE:
REASONING: Corals live in warm, shallow oceans,
so the fossil corals found in Illinois
rocks tell us that Illinois used to be a
warm, shallow ocean 450 million
years ago.
Illinois used to be a warm shallow ocean
450 million year old coral fossils
26.
27. Silurian Period - 455 million years ago
Ron Blakey
The world in the Silurian Period (455 million years ago)
Red dot shows Chicago’s approximate location
Editor's Notes
We will use fossils from the past to reconstruct paleoenvironments
Paleontology is the study of prehistoric life, including organisms' evolution and interactions with each other and their environments (their paleoecology). As a "historical science" it tries to explain causes rather than conduct experiments to observe effects.
Paleontologist Charles Doolittle Walcott (1850-1927) was appointed the fourth Secretary of the Smithsonian in January 1907, after serving as director of the U.S. Geological Survey. His research on North American Cambrian fossils took him to sites throughout the United States and Canada. In 1909, while collecting in the Canadian Rockies, he discovered the first fossils of an enormous trove of rare, carbonized, soft-bodied fauna from the Cambrian Period. He dubbed the fossils the Burgess Shale after nearby Mount Burgess. The find was so extensive, and the creatures so foreign and new to science, that Walcott returned to the field for the next five summers straight, and then made additional periodic trips up until 1924. Because they revealed the range and diversity of life in the ancient seas, these exquisite and unusual soft-bodied fauna have come to be recognized as one of the most important geologic discoveries of the twentieth century. These fossils have served as the foundation for the study of the Cambrian Period in western North America
All extinct genus, all related to modern arthropods (from top left, and clockwise)
Trilobite (~10 cm)
Hallucigenia (~ 3 cm) – a kind of spiny worm
Anomalocaris (~ 1 meter long) – arthropod – relative of insects, arachnids, and crustaceans (disk-like mouth with rows of overlapping plates, stalk eyes with 16,000 lenses, 2 arms with barb-like spikes) – top of the food chains of Cambrian seas
Marella – most common animal of Burgess Shale – arthropod, not a trilobite ~ 2.5 cm long
Walcott often took his family along on collecting trips (Helena, Benjamin, Helen peeking behind mom)
DAY 1
You will be looking for fossils in the creek for a while (it is July and the summer heat is beating down on you. You can’t come out in the winter b/c the ground is frozen and snow covered)
Your hard work has paid off: Your team has found and excavated 3 fossil bones – an exciting discovery! (take 3 bones out of the envelope)
You can see more bones, but the sun is setting and you cannot extract them today. You go back to camp
DAY 2
Keep working in the field
Today your team extracts 5 bones (each person takes out 1 bone)
DAY 3
Keep working in the field
Today your team extracts 5 bones (each person takes out 1 bone)
DAY 4
Keep working in the field
Today your team extracts 5 bones (each person takes out 1 bone)
Back at camp, after a delicious camp stove cooked meal, your team begins to assemble the bones together.
Since the bones were all found together in what looked like an undisturbed rock layer, it is reasonable to think they belong to the same animal/organism.
You may use the Skeletal Resource Manual to help you along (do this while they are working, or tell them they can open it up at the end)
Work on this task for a few more minutes, fill in worksheet.
Back at camp each night:
Students revisit their reconstruction as they incorporate their finds
Discussions and debates are encouraged – this is part of working as a team
After the last bones are found:
Make a last sketch
Tell them another team working in the area made two new discoveries: see next slide
Key aspects of the Nature of Science to highlight
Scientific Knowledge is Based on Empirical Evidence
Scientific Knowledge is Open to Revision in Light of New Evidence
A tooth- looks like a herbivore’s tooth (lead them to that – does it look like a dog’s tooth, pointy and used to cut meat, or like an elephant’s tooh, flat and used to grind and mash vegetation)
Fur – what does this tell you about the animal (mammal, lived in colder climate)
SHARE:
Have each team present what they think they’ve reconstructed
What type of animal do you think you have (mammal, bird, fish, etc.)?
What kind of environment did this animal likely live?
Would this animal be able to live in Illinois today?
Paleontology – and all science –
…is constantly changing
…requires and uses creativity and art
…is inextricably connected to scientists experiences, preconceptions, and biases
Scientific knowledge is simultaneously reliable and tentative. Having confidence in scientific knowledge is reasonable while realizing that such knowledge may be abandoned or modified in light of new evidence or reconceptualization of prior evidence and knowledge.
(Alexander Anderson’s drawing of the New York Mammoth, 1802)
Paleontology – and all science –
…is constantly changing
…requires and uses creativity and art
…is inextricably connected to scientists experiences, preconceptions, and biases
This is a more modern understanding, based on lots of data collection, analysis, and review, of what a mammoth looked like.
Is it subject to change? Absolutely!
NOS
- Science knowledge is based upon logical and conceptual connections between evidence and explanations.
ClaimWrite a statement that answers the key question
- Let’s use the evidence that we collected (10,000 year old fossil mammoth) to make a claim about Illinois past climate
- What do you know/ what can you infer about this animal based on its physical characteristics?
EvidenceProvide appropriate and sufficient data to support your claim.
Fossil mammoths, covered in fur, layers of fat
ReasoningUse scientific principles to explain why your evidence supports your claim.
The Illinois region has a rich record of large Pleistocene animals, with mammoths being perhaps the most famous. Mammoths were large grazing animals that haunted the grasslands at the edge of retreating and advancing glaciers during the most recent Ice Age, 18-10,000 years ago. They are modern elephants’ first cousins: hairier and with longer tusks, but with similar teeth and skull structure. They lived and died in the open fields, and their remains, often quite scattered and incomplete, are found in wetlands and river beds. Mammoths were exceptionally adapted to the cold climate of the last Ice Age, with heavy coats, thick blubber under their skins, and circulatory adaptations that prevented their blood from freezing solid. Mammoths were abundant in Illinois until 10-11,000 years ago, when they went extinct, succumbing to sudden environmental change and overhunting by early humans.
This map shows how North America appeared about 18,000 years ago. During the Pleistocene, repeated glaciations occurred, some of which covered parts of northern Illinois. This was the time period that many people have labeled the "Ice Age." The glacial ice that advanced from northern Canada created many of the features we see on the landscape today, such as the Great Lakes.
Ice sheet was 1 mile thick in Chicago during the peak of the last glaciation (Wisconsian, ~14,000ya)
STABILITY AND CHANGE
Life has not always been what it is today, it has changed and continues to change over time.
If we look at a single organism, or a single point in time, it may look unchanging
Think back to bell ringer. What were the ways in which the ice cube was stable and changing?
- We can use that same thinking with the mammoths – if we look at the presence/absence of mammoths on Earth, we begin to see a story of change, where an ice age gave way to a warming period and mammoths went extinct.
Mammoths are not the only animal that was abundant in Illinois but has long since disappeared. A walk along the shore of Lake Michigan in Chicago is likely to bring you across some interesting fossils.
Pass out fossils rock samples such as Illinois Silurian limestone to each of the students, and ask students to:
Sketch their fossil. Does it remind you of any organism you know?
Based on what they know or imagine about this organism, draw what they think this animal looked like when it was alive
After they have examined their fossil, pass out Illinois Fossil Sheet and ask students to:
Look at their Illinois Fossil Sheet and see if they can find any organism there that is similar to the one they sketched.
Look through the sheet and determine what all the organisms in the Illinois Fossil Sheet have in common (All marine organisms)
3. Share out with next slide
In what kind of environment did these organisms live?
Marine (show the crinoids, corals, gastropods, brachiopods in images)
Are they here today?
If we went into Lake Michigan (or any other of the Great Lakes) would we find corals?
No, remember the lakes formed only 10,000 years ago, and these fossils are 450 million years old – way older than the lakes!
Is there anywhere on Earth where we can find these kinds of organisms today?
Next slide
Yes! In tropical coral reefs (point out crinoids, corals, brachiopods in pictures)
What do these places look like? Next slide
This is a warm shallow ocean environment – not like the environment of Illinois today
So let’s do a CER, just like we did with the mammoth fossils, for the coral fossils
ClaimWrite a statement that answers the key question
- Let’s use the evidence that we collected (450 million old fossil corals) to make a claim about Illinois past climate
- What do you know/ what can you infer about this animal’s habitat based on its modern counterparts?
EvidenceProvide appropriate and sufficient data to support your claim.
Modern corals, crinoids, brachiopods, gastropods, etc. live in warm, shallow marine environments
ReasoningUse scientific principles to explain why your evidence supports your claim.
So how can the environment be so different?
In small groups, ask teachers to think about ways in which land that is now in a temperate climate could have been under a warm, shallow, tropical ocean.
Encourage them to think about all the Earth’s systems and how they can change environments.
Share Out
Show Paleogeography video (next slide)
Remind students that the climate in a given region may change because of changes in the energy balance between the Earth’s different systems and spheres. For instance, adding greenhouse gases to the atmosphere will increase the ability of the air to hold on to heat, which in turn will lead to global warming. Another key factor that affects climate is the position of a landmass on the globe. Over the history of the Earth, continents have moved and changed their locations as tectonic plates shift and interact with each other (connection to plate tectonics and the geosphere)
found on your CD or at http://www.youtube.com/user/lricobeck#p/a/u/1/7Qz4RPptSNU and ask them to follow the red dot on the map. Where was Illinois during the Silurian Period? Go to the Silurian map and discuss the location of the red dot. Would warm, shallow oceans be viable at this location?
