Name ______________________________
Geology 105 Earth History Lab
Museum Field Trip
Museum hours of operation: 11-4 pm daily, including weekends, closed Wednesdays.
Located on Calhoun Street, opposite the library, on the second floor of the new science building
The objectives of this lab are to:
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Identify preservational biases in the fossil record
Understand the concept of convergent evolution between non-related groups
Explore the role between climate change, plate tectonics, and major evolutionary events
Identify diet based on tooth shape
Materials:
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Hard writing surface (a copy of the blue lab manual or Marshak lab manual)
Completed/corrected pre-lab
Printed lab exercise
Pencil
Instructions:
Go over the pre-lab answers with your instructor before entering the museum. Find your group number and
the appropriate location to begin work – this lab SHOULD NOT be done in order, to prevent traffic jams
occurring at the different fossil cases!
Use the Museum Map to help you find the different fossils, and if necessary consult a docent or your
professor for assistance. All the information you need should be available in the signs or was discussed in
the pre-lab/previous lab assignments.
For the sketches: THEY DO NOT HAVE TO BE HEARTBREAKING WORKS OF STAGGERING GENIUS, but
neatness and labels help!
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PART 1: History of Oceanic Life
Groups 1-2 should begin in this part of the lab, with each group taking a different section. Use the map
for help.
Section A: THE BEGINNING
Duck around the corner, to the very beginning of the display, and you will find some EXTREMELY old rocks. Be
sure to take the opportunity to touch the 800 million year-old stromatolite on display!
1. Using the signs, what ARE stromatolites? Are they plants, animals, or bacteria?
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2. What is the age of the oldest stromatolite in the museum and where was it found?
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3. Are stromatolites still alive today? If so, what kind of depositional environment do they live in?
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4. Scientists have learned a lot about Archaen stromatolites by observing
modern ones in areas like Shark Bay, Australia. Stromatolites are
sedimentary structures constructed by blue-green algae, or cyanobacteria,
which photosynthesizes using light from the sun and CO2 from the water to
make energy. However, taking CO2 out of the water causes calcium
carbonate, or limestone, to precipitate out on top of the bacteria, forming
basically a layer of cement. Based on this information, do you think that the
inner layers of a modern stromatolite are still alive? Why or why not?
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Sketch and label a crossection
of a stromatolite, labeling the
limestone layers and the
cyanobacteria.
5. Stromatolites are layered structures created by living cells, which are only rarely preserved themselves.
Based on this, are these structures body fossils, casts, or trace fossils (use prelab for help!)? _____________
6. What important gas did these early stromatolites PRODUCE while performing photosynthesis? (check signs
for help) ________________
7. How did stromatolites change the color of the sky 2.5 billion years ago?
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8. If complex cells require oxygen in order to produce energy and make important proteins for building bodies,
why don’t we see complex eukyarotic life evolving until after 2.5 billion years ago, and what does this have
to do with stromatolites?
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9. 720 million years ago, the majority of the Earth’s surface was covered in ice due to reduced levels of carbon
dioxide in the atmosphere (the opposite of global warming!). This is referred to as the Snowball Earth
Hypothesis. If this is true, what type of sedimentary evidence would you expect to find in rocks at the
equator? Think back to Paleoclimate/Sedimentary rock lab.
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10. Walk to the right – you’ll see after the stromatolites there is a sudden explosion of fossil activity. Why do we
suddenly go from having very few simple fossils to MANY extremely diverse ones? (Hint: What sort of
organism is most likely to preserve as a fossil? How many soft-bodied organisms do you see in the display?)
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Section B: TRILOBITES
These little critters are found in the first 1/3rd of the Oceanic Display, and some are also tucked away in the
Crinoid Case. Use your observations and the signs to answer the following questions.
1. What is a trilobite? What are some distinguishing characteristics of
this arthropod? Sketch and label one of the organisms using
information from the trilobite sign.
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2. Do trilobites have internal skeletons (like humans) or external
skeletons (like crabs and shellfish)?
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3. Describe trilobite eyes.
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4. What depositional environments could trilobites have been found in?
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5. One of the main predators of trilobites were the orthocerids or nautiloids – these relatives of modern octopi
and squid had excellent eyesight and a crushing beak for nabbing these little critters. Think back to our finch
lab on natural selection. What are two traits that would have helped some of these trilobites survive – think
of features that would help them evade predators, hunt, burrow, swim, etc.?
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6. Trilobites went extinct at the end of the Permian period, approximately 251 million years ago. There is a sign
on major extinction events in the middle of the Oceanic Life display, to the right of the window with the
giant opalized ammonite. According to this sign, what are some possible causes of the extinction event that
killed the trilobites (and MANY other animals as well)?
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7. Think back to your geologic time lab. What are some ways that geologists could use to get the age of a
trilobite fossil?
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8. Why do trilobites make great index fossils for dating?
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PART TWO: Marine Vertebrate Predators
Groups 1-3 should begin with this part of the lab, and rotate through the sections.
Section A: Mosasaurs
Go to the windows facing the library, on the corner of Calhoun and Coming. Read the signs and answer
the following questions:
1. Are mosasaurs anapsid, diapsid, or synapsid? Hint: remember, only diapsids had holes in the
TOP of the skull. Circle the right answer.
2. What group of living organisms are mosasaurs related to? How can we tell? (check the signs for
help!)_________________________________________________________________________
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3. Are mosasaurs dinosaurs? _________________
4. What kind of environment did mosasaurs live in?
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5. What kind of sedimentary rocks do you think you might find with the mosasaur fossils in Kansas
and Nebraska, shown on the map next to the fossils?
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6. Why was the environment for Kansas and Nebraska during the Cretaceous different than it is
today? Think back to your paleogeography and paleoclimate labs to answer this!
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7. We know from our opalized ammonite and the tooth marks in it that mosasaurs preyed upon
this shelled squid relative, kind of like eating crunchy calamari. Which do you think is more
common in the fossil record, ammonites or mosasaurs? Why? ______________________________
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8. How many limbs/flippers does a mosasaur have? _____
9. Are mosasaur tails oriented vertically like a fish, or horizontally like a dolphin? ______________
10. Sketch a mosasaur flipper below, and make sure to include the larger humerus bone that
connects the flipper to the shoulder, as well as the smaller bones:
11. How many rows of teeth does a mosasaur have? If it has extra teeth, what do you think it was
using them for?
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12. Sketch the shape of the mosasaur tooth here:
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SECTION B: Ichthyosaurs
1. Find the ichthyosaur fossil using the map – it’s in the “Life Moves to Land” cabinet cast. If you
look in this fossil case, it also contains two groups of fish – a ray-finned perch, and a lobe-finned
coelacanth. Which do you think the ichthyosaur is more closely related to, and why?
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2. How many limbs/flippers does an ichthyosaur have? _________
3. Sketch the ichthyosaur flipper below, and be sure to include the larger bone (the humerus) that
connects the flipper to the shoulder of the animal as well as the smaller bones).
4. The word ichthyosaur means “fish lizard” in Latin. It’s commonly thought to resemble a modern
dolphin, which is a mammal, but it has a skull with a hole in the top of the head. Circle the
group you think an ichthyosaur belongs to: anapsid, diapsid, or synapsid. (Read the signs and
remember your tetrapod lab for help.)
5. What features does an icthyosaur have that make it adapted for a life in the water?
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6. It’s difficult to see using the fossil, but an ichthyosaur only has a single row of teeth. Sketch the
shape of one of the teeth here.
7. What kind of tail does an ichthyosaur have – is it oriented vertically, like a shark, or horizontally,
like a dolphin? _______________
SECTION C: Sharks
1. Using the map, you should be able to find the Megalodon shark jaw in the Shark Exhibit. How
many rows of teeth does the megalodon have? ____
2. Sketch a Megalodon tooth here:
3. Why are teeth the most common fossil to find for sharks, with other body parts like skulls,
vertebrae, etc being rare? Think about what a shark’s skeleton is made of!
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4. Does a shark swim using an up-down tail movement of its tail like a dolphin, or side-to-side
movement like a fish? _________________
5. Are the flukes/fins of a shark’s tail vertical or horizontal? _________________________
6. Helicoprion is one of the strangest fossils known to science - paleontologists have come up with
50+ theories for what exactly it was used for, but we’ll probably have to find more spectacular
soft-tissue preservation to know for sure. Come up with your own hypothesis how this Permian
shark may have used these teeth. No wrong answers - be creative!
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SECTION D - WHALES
Go to the whale exhibit – the room outside the main museum. In the front case, you’ll see the
forelimbs of whales ranging from the ancestral ~47 million year old Maiacetus, to the flipper of a
modern dolphin.
1. How many limbs/flippers does a dolphin have? _____
2. What happened to the hind limbs of a dolphin?
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3. Does a whale swim using an up-down tail movement of its tail, or side-to-side?
_________________
4. Are the flukes/fins of a whale tail vertical or horizontal? _________________________
5. Sketch the flipper of a dolphin below. Be sure to include to the larger main bone (the humerus)
that connects the flipper to the shoulder as well as the smaller bones.
6. This exhibit also has a series of toothed whale skulls. Sketch the ancestral tooth of a Maiacetus
and the tooth of a modern bottlenose dolphin (Tursiops) below.
7. Of the Maiacetus and the modern dolphin, which do you think took bites out of prey, and which
do you think pierced fish and swallowed them whole?
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8. What group of living terrestrial mammals are whales most closely related to (remember to read
the signs!)? How do we know this?
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9. List at least four ways in which modern whales have changed from the earlier, ancestral whales
(archaeocetes) –specifically look at teeth, ears, limbs, and nostrils!
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FINAL SECTION E - Convergent Evolution
The similarities between these four predators (mosasaurs, ichthyosaurs, sharks, and whales), despite
their very different ancestry, is a result of what is called CONVERGENT EVOLUTION. Organisms
which are not closely related nonetheless independently develop similar traits due to living in similar
ecosystems or niches – basically, they adapt to similar lifestyles, such swimming quickly in open water
and feeding on fish. You’ll see many examples of convergent evolution as we continue to go through
the museum.
Now that you’ve been through this section…
1. What are 3-4 characteristics that mosasaurs, ichthyosaurs, and modern dolphins share?
2. What are some major differences?
3. Of these four predators (mosasaurs, ichthyosaurs, sharks, and whales), which had ancestors that
lived on land and later returned to the sea? Explain your answer.
4. Which two of these three are more closely related to each other: ichthyosaurs, mosasaurs, and
dolphins? Explain your answer. HINT: THINK SKULL TYPES.
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PART THREE: LIFE IN THE ICE AGE
Groups 4-6 should begin here, and split up to start with different sections
Section A: Ice Age Megafauna
Enter the Ice Age! Go to the window facing the library, filled with Pleistocene
Megafauna (aka the giant mammals).
1. In the windows you’ll several awesome examples of Ice Age animals. These animals are much larger
than their modern counterparts - list three that are still alive today (although as much smaller
versions of their Pleistocene relatives!).
A. ___________________________________
B. ___________________________________
C. ___________________________________
2. Here are two images of extant tree sloths. Do you think the extinct sloths in the exhibit were living
in trees? Why or why not?
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3. Check out the claws on the three sloth species, in both the fossils and the signs! What do you think
these claws were for? How did the extinct sloths keep these claws sharp despite being a grounddwelling species (compare the claws of terrestrial mammals like cats, dogs, and the sloths and
examine the pictures).
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4. Given what we know about the climate during the ICE AGE, how does this potentially explain why
the mammals present during the Pleistocene are much larger than the ones alive today? What
makes these large sizes adaptive for the environments these sloths, armadillos, and beavers lived
in? (Here’s a hint: which cools more quickly, a large cup of coffee or a small one?)
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The principle behind this
concept is known as
Bergmann’s rule, and can
be seen in action in the
present as well as the past –
larger species tend to live in
colder, higher latitudes,
while smaller ones live in the
tropics. Consider the size of
the key deer shown here,
found in the Florida Keys,
compared to the largest
living deer species, the
moose.
Section B – Sabertoothed Predator Evolution
1. During the Pleistocene ice ages, the sabertoothed cat evolved specifically to prey on megafauna
– aka, animals much, much larger than itself. Looking at the Xenosmilus skeleton in the Ice Age
Megafauna exhibit and using the information in the signs, what are four traits it has that make
it well-adapted to this particular predatory niche?
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While megafauna and sabertoothed cats were evolving in
North America, Africa, Europe, and Asia, South America
was completely separated from the rest of the continents,
much like Australia today, and was populated primarily by
marsupials – mammals that give birth to premature young
in pouches. These also attained much larger sizes than
their current counterparts, due to the colder climate.
There is a marsupial predator found during this time –
Thylacosmilus, pictured here (unfortunately we don’t have
a specimen in the museum, so we’ll have to settle for
pictures for now!).
2. What sort of prey would you predict Thylacosmilus
was hunting? Why?
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3. Do you think the marsupial Thylacosmilus and the feline Xenosmilus inherited their sabershaped teeth from a common ancestor, or did they evolve the teeth independently? Why or
why not?
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4. Take a look at the nimravids (the false sabertooth cats – see the red star on your museum map
for help!) in the far right end of the Oligocene Mammal Case. Based on what you now know
about sabertooth cats, what size prey did these carnivores eat?
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5. What is the geologic range of these species (ie, when did they first appear in the fossil record,
and when did they disappear)?
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6. True feline sabertoothed cats, such as Xenosmilus did not evolve until the Pliocene,
approximately 3 million years ago. Are nimravids the ancestors of these sabertoothed animals?
Why or why not?
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PART FOUR: Dinosaurs and more!
Groups 7-9 should begin here, and split up to start with different sections
Section A: Dinosaur Traces
1. Find three examples of trace fossils in the dinosaur case:
a. Name: ____________________
Geologic Age: _____________
Description:
b. Name: ____________________
Geologic Age: _____________
Description:
c. Name: ____________________
Geologic Age: _____________
Description:
2. There are a number of interesting aspects of the Psittachosaurus skeleton – it was found
completely intact, for one thing, due to the fact it was in a burrow that collapsed, thus burying
and preserving it in perfect condition. What are some reasons that a skeleton might not be
found in such good condition?
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Section B: Teeth & Etc
Teeth can tell a paleontologist a lot about the diet and lifestyle of an extinct animal. For example,
sharp, cutting molars with many scissor-like edges (cusps) slice and tear meat; flat, ridged molars are
excellent for grinding and processing plants.
1. Go to the Oligocene Mammals of North America case (check map for help locating this).
Compare the diets of these three groups: creodonts, entelodonts, and brontotheres. Based on
the shapes of their molars – i.e., were they omnivorous, carnivorous, or herbivorous?
Creodont: _______________
Entelodont: ______________
Brontothere: _____________
2. Go to the Cave Bear exhibit, and look at the back molars of the animal on display. Do you think
this animal was a carnivore or an herbivore? _________________
3. Return to the Oligocene Mammals, and find the Protoceras celer skull near the top left of the
Oligocene Mammals exhibit – it looks a lot like a dragon, with multiple pronged horns and
elongated canines. Look at their back molars. Did they eat meat or plants? _____________
4. If it didn’t eat meat, what was Protoceras using its saber-like canines for? (hint: think about
what deer use their antlers for)
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5. Do you think the Protoceras is closely related to the sabertoothed cats on display?
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6. Beneath the Protoceras celer skull and to the left, there are some spectacular fossils of
articulated skeletons of camels and tiny hooved burrowing animals called oreodonts –
articulated means that individuals were found with all of their bones already in place. Based on
what you learned in the pre-lab, do you think these animals were buried slowly, or quickly?
__________________
7. Unfortunately you can’t touch the rock these specimens are embedded in, but make a
prediction based on what you learned from the pre-lab – were these animals buried in coarse
sand, or a fine-grained mud? ____________________
8. Do we still find oreodonts or camels living in North America? __________
Section 3: Dinosaurs vs Elephants
In this section, you’ll be going back and forth across to the dinosaur, elephant and Oligocene mammal
exhibits, observing and comparing the dentition of various species.
1. We have a skull of a duck-billed hadrosaur in the dinosaur
exhibit, which replaced their teeth constantly throughout
their lives, much like a shark. Sketch a tooth row of a
hadrosaur here:
2. Now go to the Southeastern Elephants case (check map for
location). In it we have three different groups of elephant
that once lived in this area – mammoths, mastodons, and
gomphotheres. Elephants also replace their teeth
throughout their life, but they only have 6 sets – after the
last set wears out, they can no longer grind their food and
wind up dying. Sketch a mammoth tooth here.
3. Both mammoths and hadrosaurs are grazers, aka animals which process extremely tough, gritty
foods like pine needles or grasses. Their teeth shapes allowed them to grind their food in their
mouths until it was well-broken down for digestion. Sauropods like the Saltasaurus in our
Dinosaur exhibit also ate tough food, but instead of having grating teeth for chewing, had very
simple peg-like teeth and probably didn’t chew at all. So how did sauropods manage to survive
and eat tough food despite their flimsy, tiny teeth? (Hint: we have found many sauropod fossils
with round, polished stones called gastroliths in their stomach area).
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PART FIVE: Convergent Evolution (do only when entire
rest of the lab exercise is complete!)
1. Define convergent evolution in your own words.
2. Explain 3 of the examples that you’ve seen in the museum today.
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