Table of Contents Chapter Lecture Tutorial Title Page




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Table of Contents

Chapter Lecture Tutorial Title Page
Chapter 1 Finding Dinosaur Fossils 2
Chapter 2 Dating Dinosaurs 4
Chapter 3 Reading Cladograms 6

Cladograms 8

Cladograms and Evolutionary Trees 10
Chapter 4 Discovering Relationships 12

The Classification of Amniotes 14

What Is a Dinosaur? 16
Chapter 5 Eating Habits of Ankylosaurs 18
Chapter 6 Pachycephalosaur Living Environments 20

The Function of Ceratopsian Frills 22


Chapter 7 Social Behavior of Hadrosaurids 24
Chapter 8 Sauropod Nests 26
Chapter 9 Large Theropods 27
Chapter 10 Evolution for Flight 29
Chapter 11 Bird Evolution 31
Chapter 12 Comparing Dinosaur Thermoregulation 33
Chapter 13 Dinosaur Movie Scenarios 35
Chapter 14 none
Chapter 15 Possible Causes of Dinosaur Extinction 36




Part 1: Basic Criteria

The following three basic criteria maximize the likelihood of finding dinosaur fossils:

1) The rock type must be sedimentary (made out of sediments, such as sand and mud, deposited on the surface of the Earth).

2) The rocks must be of the right age.

3) The rocks must originally form on land instead of ocean.
1) Explain why sedimentary rocks are better to find dinosaurs than rocks that were once lava flows (igneous rocks).

2) Explain why sedimentary rocks are better to find dinosaurs than rocks that formed by extreme pressure and high temperatures deep beneath the surface (metamorphic rocks).


3) During what time frame did dinosaurs live?


4) Why would you want to look at rocks that originally formed on land and not in the ocean?



Part 2: Sponsoring Dinosaur Collecting

You have money and want to support paleontologists who want to collect dinosaurs. Five paleontologists approach you and describe areas in which they want to search.


Paleontologist A: I would like to look in an area where a volcano erupted 100 million years ago (Cretaceous age). The rocks are volcanic in the area.
Paleontologist B: I would like to search an area where you find Jurassic aged (180 million years old) sedimentary rocks with lots of other fossils, such as clams, coral, and sea urchins.
Paleontologist C: I would like to look for dinosaurs in an area that I think was probably desert, or it might have been a beach – I’m not too sure. The rocks are likely somewhere around 150 million years old, plus or minus, which makes them Jurassic in age.
Paleontologist D: I would like to search in an area that was a river valley that occasionally flooded. The sedimentary rocks are Cretaceous in age (130 million years old).
Paleontologist E: I would like to search an area that is full of Paleozoic (540 - 251 million years old) sedimentary rocks that were originally deposited on a lake shore.
5) Because of limited funds, you can only support one paleontologist. Which paleontologist would you support and why?

6) Explain to the other paleontologists why you are NOT supporting their search for dinosaurs.


Paleontologist ___ because…

Paleontologist ___ because…

Paleontologist ___ because…

Paleontologist ___ because…

7) Compare your selection with that of another group of students. If the selections are different, then convince them your selection is more logical.



Part 1: Stratigraphy

There are several different ways to tell us how old or young rocks are. These are:


• Chronostratigraphy (ages in years before present)

• Lithostratigraphy (determining the relative ages of rocks)

• Biostratigraphy (ages indicated by fossils)
1) Determine which of the three methods of dating rocks is used in each of the scenarios below.
_______________ Radioactive potassium tells us the rock is 500 million years old.
_______________ Because a rock contains dinosaur fossils, the rock is Mesozoic in age.
_______________ This rock layer is older than that other rock layer.
2) Chronostratigraphy is primarily done only on rock that forms from cooled magma. Why can’t chronostratigraphy be used to directly date the rocks in which dinosaurs are found?
Part 2: Determining the Age of a Dinosaur

Examine the diagram to the right showing a vertical sequence of rock layers, with the oldest rocks on the bottom and the youngest rocks on top (Ma = million years old).


3) Which of the three stratigraphy methods was used to determine the age of the cooled magma layers?

4) Which of the three stratigraphy methods was used to determine the age of the sedimentary rock with the shell fossils?

5) What is the age or age range of the dinosaur?

6) How did you determine the age of the dinosaur?


7) Based on the ages given in the diagram, were the sediments that formed the sedimentary rock layers deposited at a constant rate? Explain your answer.

8) Two students are debating the age of the dinosaur in the diagram.


Student 1: I think the dinosaur is between 200 and 170 Ma (million years old). You don’t know how long it took for the sedimentary layers to be deposited, so you can’t be more exact.
Student 2: Because there is an extra layer, I think the age is closer to 170 Ma. So, the age of the dinosaur is between 185 and 170 Ma.
With which student do you agree? Why?
9) Why is it very difficult to precisely determine the age of a particular fossil in a sedimentary rock?

10) Why are all three stratigraphy techniques (chronostratigraphy, lithostratigraphy, and biostratigraphy) necessary for determining the age of dinosaurs?




Part 1: Different Depictions

In paleontology, cladograms are depicted in a variety of ways, all showing the same basic idea of groups within larger groups.




1) Which letter on each of the other diagrams shares the same position as A? (circle one letter per diagram)

F G H K L M
2) For each diagram, which two letters indicate branches that share the most characteristics, so are most similar to each other? (circle two letters per diagram)

A B C F G H K L M


3) For each diagram, which letter is most distantly related to the other two letters? (circle one letter per diagram)

A B C F G H K L M


4) For the center diagram, would the same information be conveyed if you switched G and H? Explain your answer.

5) For the right diagram, would the same information be conveyed if you switched K and L? Explain your answer.


6) For the left diagram, would the same information be conveyed if you switched B and C? Explain your answer.


7) As shown above, the cladograms indicate groupings that are not about relationships. Now we’ll put some animals on the cladograms, arranged in a way to show relationship. If, for example, you were to put earthworms, turtles, and dinosaurs on the diagrams, at which node would earthworms be located on each of the three diagrams? (circle one letter per diagram)

A B C F G H K L M
8) If you were to put earthworms, turtles, and dinosaurs on the diagrams, which of the letters below is NOT a place you could put dinosaurs? (circle all that apply)

A B G H K L


9) Check with another group of students that you have the same two letters circled for Question 8.

Part 2: Adding Animals

Examine the cladograms below showing relationships between beetles, cats and humans.



10) Which cladogram, if any, is more correct? Explain your answer.


11) Two students are debating which cladogram is more correct.
Student 1: I think they’re both equally as correct. They both show that humans and cats are more closely related to each other than to beetles.
Student 2: I think Cladogram A is more correct because it shows humans at the far end. Cats are closer to beetles and humans aren’t closely related to beetles, so A is better.
With which student do you agree? Why?
12) Compare your answers to Question 10 and 11 to your answer to Question 6. Change any answers as necessary.
13) Why does the order on the top of the cladogram not necessarily indicate how closely organisms are related?
14) Draw two separate cladograms below, both showing the correct relationship between jellyfish, dinosaurs, and pigs.


Part 1: Cladogram Basics

Below is a simple cladogram. Cladograms are constructed based on diagnostic (“derived”), shared features of organisms, and, as a result, they show relationships between organisms. The bars indicate characteristics that describe all organisms on the cladogram connected at the related node. The open circles at each node are used to give names to the groups of all organisms united at that node.



1) What is a diagnostic character illustrated by Bar 3?


a. four limbs

b. backbone

c. endothermy (warm-bloodedness)
2) What diagnostic character (labeled by Bar 2) do organisms united at Node B share?
a. four limbs

b. backbone

c. endothermy (warm-bloodedness)
3) What is a possible name that can be given to the organisms united at Node B?
a. animal

b. vertebrate (animal with a backbone)

c. mammal
4) Two students are debating the name that can be given to organisms united at Node B.
Student 1: I think that the organisms included in Node B should be called animals. Everything on the cladogram is an animal, so I think that description fits for Node B..
Student 2: Node B should just label only the organisms united at Node B. Since everything connected at the node has a backbone and worms don’t have a backbone, I think the organisms included in Node B should be called vertebrates.
With which student do you agree? Why?
5) Which animal do lizards share the most key characteristics with? Goldfish Elephant
6) Which animal are lizards most closely related to? Goldfish Elephant

Explain your answer.




Part 2: Constructing a Cladogram

7) Draw a cladogram below showing the relationship between: snails, bluebirds, and turtles. (note: Keep in mind that wings are limbs!)

8) On your cladogram, label 2 shared, diagnostic characteristics using bars similar to the previous cladogram.
9) On your cladogram, give the organisms united at each node a name, using small circles similar to the previous cladogram.
10) Two students are debating the relationship between snails, bluebirds, and turtles.
Student 1: I think that bluebirds and turtles are most closely related. They both have backbones and four limbs. So, they are closely related because they are both located in the node I called “vertebrates.”
Student 2: I think that snails and turtles are most closely related. They both have shells, so they are more similar, and I put them on the same node in my cladogram.
With which student do you agree? Why?
11) Why is it important to pick important characteristics (called diagnostic characteristics) when creating a cladogram?



Part 1: Cladograms

Cladograms show relationships between organisms. Use the cladogram below to answer the questions.


1) Based on the cladogram, what are alligators most closely related to?
Swordfish Frog
T. rex Not specified
2) On the cladogram, what is the ancestor of the T. rex?
Swordfish Frog
Alligator Not specified

Part 2: Evolutionary Trees

Evolutionary trees show ancestors and descendents. The evolutionary tree below shows the evolutionary relationships inferred from the cladogram.


3) If we find a fossil, how likely is it to be the actual ‘Ancestor to alligators and T. rex’ at Node C?

4) Will we ever know definitely if a fossil that is found is the ‘Ancestor to alligators and T. rex’ at Node C?

5) Can you determine what organism is the ancestor of another organism on a cladogram? Explain your answer.

6) Three students are debating the answer to whether or not it is possible to determine the ancestor or organisms on cladograms.


Student 1: Yes, animals that branch off are ancestors to later animals. For example, lizards are ancestors to crocodiles and dinosaurs.
Student 2: No, the branches don’t show ancestors. But, if we find a fossil that we know is an ancestor, we can put it at a node on the cladogram. This will show that it is an ancestor and we can see the descendents.
Student 3: I agree that the branches don’t show ancestors. But we will never know if one fossil is a direct ancestor to another fossil, so we cannot show ancestors on a cladogram. We can only show features that an ancestor likely had.
With which student do you agree? Why?

7) Look at your answer to Question 2 and revise your answer if necessary. Explain below why the correct answer is “Not specified.”

8) Explain how cladograms show different information than typical evolutionary trees.



Part 1: Lungfish, Lion, and Goldfish

The table below lists some characteristics of lungfish, lions, and goldfish.







Goldfish

Lungfish

Lions

Shoulder girdle

No

Yes

Yes

Bony skeleton

Yes

Yes

Yes

Humerus, ulna and radius bones

No

Yes

Yes

Lungs

No

Yes

Yes

Hair

No

No

Yes

1) Below are cladograms that show the two possible relationships between the three animals. Draw lines indicating where each of the five characters in the table appear in each cladogram. Some characters may need to be drawn more than once, or you may need to indicate the disappearance of a character. The character of shoulder girdle has been drawn in for you.





2) Based on your labels, which cladogram is the most parsimonious (requires the fewest number of changes)?

A B
3) Therefore, to which animal is the lungfish most closely related?
goldfish lion
4) If the goldfish and lungfish are both formally classified as fish, why must the lion also be called a fish? Use the cladogram to support your answer.

5) Why does the term “fish” not show evolutionary relationships?



Part 2: Bird, Crocodile, Lizard

6) Based on what you know about birds, crocodiles, and lizards, make a prediction about which two are most closely related. Justify your predication.

The table below lists some characteristics of birds, crocodiles, and lizards.





Bird

Crocodile

Lizard

Amniote egg

Yes

Yes

Yes

Two temporal openings in the skull roof

Yes

Yes

Yes

Antorbital fenestra (opening in skull)

Yes

Yes

No

7) Below are cladograms that show the two possible relationships between the three animals. Draw lines indicating where each of the four characters in the table appear in the cladogram. Some characters may need to be drawn more than once, or you may need to indicate the disappearance of a character.


8) Based on your labels, which cladogram is the most parsimonious (requires the fewest number of changes)?

A B
9) Therefore, to which animal is the crocodile most closely related?
bird lizard
10) If the lizard and crocodile are both classified as reptiles, why must the bird also be called a reptile? Use the cladogram to support your answer.
11) Explain why traditional classification does not necessarily show the evolutionary relationships between animals.



Part 1: Constructing a Cladogram
1
+
) Fill in the chart below comparing characteristics of a salamander, a turtle, an elephant, an alligator, Stegosaurus, and a chicken. Use a if the animal displays the trait or a O if it does not. Some boxes have been filled in for you.





salamander

(“amphibian”)

turtle

(“reptile”)

elephant

(“mammal”)

Alligator

(“reptile”)

Stegosaurus

(“reptile”)

chicken

(“bird”)

vertebrae




















tetrapod



















anmiotic egg

O
















synapsid

condition



O

O

+

O

O

O

diapsid

condition



O
















antorbital

opening


O
















pubis points

backwards



O

O

O

O

+

O

2) Using the information in the above chart, create a cladogram showing the relationships between the six animals. Use the characters given in the table to label the changes that occur between the nodes of the cladogram.



Part 2: Analyzing Relationships
3) Circle the “reptile” group.
4) What two animals are included in “reptiles” that are normally not called reptiles?

5) Two students are debating the grouping of birds.


Student 1: According to this cladogram, birds and mammals are reptiles.
Student 2: I disagree. Birds and reptiles and mammals are different, so how can they be in the same natural grouping?
With which student do you agree? Why?

6) Why are the terms “reptiles,” “birds,” and “mammals” not useful when you look at the world using cladistics?

7) With which animal is Stegosaurus most closely related? Alligator Chicken
Why?
8) Two students are debating the relationship between dinosaurs, birds, and alligators.
Student 1: Well, dinosaurs and birds must be more closely related to each other than either is to an alligator because they both have an antorbital opening.
Student 2: I don’t think so. The cladogram shows that first alligators come off and then dinosaurs come off. Birds come off last. So alligators and dinosaurs must be most closely related. Besides, they’re more primitive than birds.
With which student do you agree? Why?



Part 1: Dinosaur Cladogram

Dinosaurs are animals that all descended from a common ancestor that was itself a dinosaur (the first one!), and they are all encompassed within the dinosaur clade on a cladogram.



1) What are the two groups within Dinosauria? ___________________ ___________________


2) What is the closest relative to dinosaurs on the cladogram? ___________________
3) According to the cladogram, can an animal be a dinosaur and not be part of Ornithischia or Saurischia? Explain your answer.

4) Circle the dinosaurs in the following pictures:




Part 2: Ornithischia and Saurischia

An easy way to tell apart Ornithischia and Saurischia is the shape of their pelvis. Ornithischians have a pelvis where at least part of the pubis runs towards the back of the dinosaur along the lower part of the ischium. Saurischians have a pelvis in which the pubis is directed towards the front of the dinosaur and slightly downward.


The figure to the right shows the three bones in the pelvis of a saurischian dinosaur. The tail is to the right.

5) Label the bones in the pelvis for the ornithschian and saurischian dinosaurs shown below.



6) To what group of dinosaurs (Ornithischia or Saurischia) do the two skeletons below belong?





Part 1: Mouths

Ankylosaur mouths can be used to help determine the eating habits of ankylosaurs. Some characters indicate that they chewed well; others suggest that chewing was not an important part of their behavior.


1) For each line of evidence, determine which eating habit the evidence supports.
a) small triangular teeth chewed didn’t chew
b) wear on teeth indicates grinding chewed didn’t chew
c) teeth not tightly packed together chewed didn’t chew
d) long, flexible tongue chewed didn’t chew
e) well developed cheeks chewed didn’t chew
f) relatively large and strong jaw bones chewed didn’t chew
g) extremely broad girth chewed didn’t chew
2) Based on the evidence in the mouth, explain whether you think the ankylosaurs chewed their food, did not chew their food, or partially chewed their food. Explain your answer.

Part 2: Comparisons to Living Animals

Features of ankylosaurs can be compared to features of living animals to help determine the ankylosaurs’ eating habits.


3) Fill in the chart below with evidence you would find in the fossil record based on the eating habits of some modern animals.


Animal

Eating Habit

Evidence That Would Be Left in the Fossil Record

Cows

Chew their food; bacteria in the stomachs in their large abdomen decompose tough plant material





Birds

Swallow food whole; stones within the muscular part of their stomach grind food





Dogs

Tear flesh with sharp teeth




4) Compared to other animals, ankylosaurs have an enormous abdomen indicating large guts. Based on this evidence, with which animal did ankylosaurs most likely share eating habits?


Cows Birds Dogs
Explain your answer.

Part 3: Conclusion

5) Based on the overall evidence, explain the eating habits of ankylosaurs.






Part 1: Condition of Bones

The condition in which fossils are found indicate if the animal died in that location or if its bones were transported to that location. Each scenario results in different interpretations as to where the animal lived.


1) For each line of evidence, indicate whether the animal likely died and was fossilized in or near that location or if the animal (or its bones) was transported after it died.
a) articulated skeleton fossilized in place transported

(all bones found together in place)


b) few scattered bones fossilized in place transported
c) bones show signs of water-wear on their surface fossilized in place transported
d) delicate features on bones preserved fossilized in place transported
e) small bones found with large ones fossilized in place transported
f) only strong, robust bones found fossilized in place transported
Part 2: Pachycephalosaur Fossils

In Asia, pachycephalosaurs are found in rocks that indicate the area was once a large desert. The skeletons are often complete and the bones are beautifully preserved with little evidence of abrasion.


2) Did pachycephalosaurs in Asia fossilize near where they died, or were their skeletons transported? Explain your reasoning.

In North America, pachycephalosaurs are found in rocks that indicate a broad coastal plain built from sediment eroding from the Rocky Mountains and washed onto the coastal plain by large rivers. Thick, skull caps, often with a water-worn appearance, are often found alone. No articulated skeletons are found.


3) Did pachycephalosaurs in North America fossilize near where they died, or were their skeletons transported? Explain your reasoning.

4) Based on the evidence of the bones, did pachycephalosaurs in Asia and North America live in similar environments? What were the environments in which each of them lived?


5) Two students are debating the where pachycephalosaurs lived in North America.
Student 1: They must have lived in the mountains or near their base, since the evidence suggests their bones were washed down with the sediments out of the mountains.
Student 2: I think they lived in the broad, coastal plain, since that’s where they were found, and it seems like a much more practical environment for a dinosaur to live.
With which student do you agree? Why?

6) Based on the environment in which they lived, what living animal might North American pachycephalosaurs resemble?


bighorn sheep bison rhinoceros

7) Based on the environment in which they lived, what may have been a survival strategy for Asian and North American pachycephalosaurs?


Live where other animals do not live, so there is little competition
Defend themselves and avoid dangerous injuries with their “helmet” head
Camouflage well, so predators are avoided
Explain your answer.

8) Pachycephalosaurs are relatively rare dinosaurs in North America. Does this fact make sense in light of where they likely lived?




Part 1: Hypothesis

Two hypotheses of the function of ceratopsian frills are:

a) protection and defense

b) intraspecies competition and to a lesser extent, display (display to other ceratopsians of the same species, often related to mating behavior)


1) Which hypothesis do you think is most likely to be correct?

Explain your answer.

2) Since it is impossible to observe the behavior of live ceratopsians, describe two ways that we learn about the function of ceratopsian frills.
Part 2: Evidence

Different lines of evidence of the function of ceratopsian frills are given below. For each line of evidence, determine which hypothesis (or hypotheses) the evidence supports and give a short explanation why.


3) In most horned mammals today, the larger males with the larger horns or antlers breed more often than smaller males. They successfully fend off competitors and impress females.

4) In Protoceratops, the frill does not grow large until the individual approaches adult body size.

5) In many cases, ceratopsian frills have large openings and in some cases, such as Protoceratops and Chasmosaurus, are made very delicately.

6) Bone beds show the animals lives in large herds in highly social circumstances.

7) Elaborate scallops and spikes are located along the frill margin of many species.

8) Ceratopsian frills are decorated with a variety of hornlets and come in many different shapes, sizes, and appearances.

9) Frills of Protoceratops show two populations, interpreted to be differences between males and females.

Part 3: Conclusion

10) Examine your answers in Part 2. Which hypothesis is best supported by the data? Explain your answer.




Part 1: Living in Herds

1) Bonebeds that contain thousands of hadrosaurids have been found. What does this tell us about whether hadrosaurids lived in groups or were solitary?



Part 2: Crests

Since hadrosaurids lived in groups, we would expect them to have some sort of social behavior. Animals that live in groups tend to communicate with other animals of the same species, and they also often have some sort of sexual selection, where one sex of the species competes for the other sex’s attention.


2) The crest of hadrosaurids is thought to have been used to make loud, deep trumpet sounds, and each species would make a different noise. How does this function tie into social behavior?
3) The crest of hadrosaurids is visually obvious, and different for each species. How does this appearance tie into social behavior?
4) The crest of hadrosaurids is sexually dimorphic, meaning that the different sexes of each species have crests that appear different from each other. How does this difference in appearance tie into social behavior?
5) Overall, what do hadrosaurid crests suggest about the social behavior of hadrosaurids?

6) There are extensive differences in the skulls in ceratopsian dinosaurs. Is it reasonable to assume they they, like hadrosaurids, may have been involved in sexual selection as well?


Part 3: Raising Young

Hadrosaurid nests have been found, and the nests also give information about the social behavior of hadrosaurids.


7) Hatchlings are found in nests with crushed eggshell fragments, indicating an extended stay in the nest. What does this indicate about the parental care of hadrosaurids?

8) Hatchlings have poorly developed joints and limbs, so they would not have been able to forage for their own food. What does this indicate about the parental care of hadrosaurids?

9) Nests are separate by a distance of one parent-length. What does this indicate about the parental care of hadrosaurids?

10) Overall, what do hadrosaurid nests suggest about the social behavior of hadrosaurids?



Part 4: Summary

11) Based on the previous information in Parts 1-3, describe the social behavior of hadrosaurids.

12) Ornithopods (hadrosaurids are a type of ornithopod) have been called the deer, bison, and sheep of the Mesozoic. Explain why this description is fitting.


The discovery of sauropod nests has given us a significant amount of information about the behavior of sauropods.


1) Thousands of sauropod eggs were found nests that covered an area larger than a square kilometer (roughly 200 football fields in area). What does this discovery tell us about the group or solitary behavior of sauropods?

2) No adults were found at the nesting site. What does this likely tell us about the parenting habits of sauropods?

3) If you were a paleontologist, what other kinds of information would you look for that could give you insights into the parenting habits of sauropods?

Animals generally display one of two strategies when raising their young. One strategy is to have a large number of offspring without providing parental care, and, due to their sheer numbers, some of them survive to reproducing age (called r-strategy). The other strategy is to have few offspring that are cared for by the parents (called k-strategy).


4) What does the discovery of sauropod nests suggest the reproducing strategy of sauropods was? Explain your answer.

5) How does the sauropod strategy compare to the strategy of other dinosaurs, such as hadrosaurs?

6) How does the sauropod strategy compare to the strategy of birds and other living reptiles?




Part 1: Convergent Evolution

Distantly related animals that live in similar environments often evolve to be more similar. For example, dolphins are mammals and swordfish are fish, so they are distantly related. However, they have the similar characteristics of a streamlined body and powerful tail because they are adapted to live in a similar environment. This phenomena of distantly related animals evolving similar characteristics is called convergent evolution.


1) Determine if the following pairs are examples of convergent evolution, and explain your answer.
bats and birds yes no because…

cows and whales yes no because…


humans and chimpanzees yes no because…


ankylosaurs and armadillos yes no because…

2) Two students are debating examples of convergent evolution.
Student 1: I think that everything except the cows and whales are examples of convergent evolution. They all look similar to each other (except the cow and whale), and they are not all that closely related.
Student 2: I think the birds and bats and the ankylosaurs and armadillos are both examples of convergent evolution. The human and chimpanzee are closely related, so they are not examples.
With which student do you agree? Why?

Part 2: Large Theropods

Large theropods share similar characteristics, such as proportionally large head and short arms. Two possible explanations for these similarities are

1) they are all closely related, or

2) they are distantly related, but have undergone convergent evolution.

To test these explanations, we will examine a cladogram showing select theropods.

The large theropods in the cladogram are the Tyrannosaurus, Allosaurus, Carnotaurus, and Ceratosaurus (all in bold). The other theropods are small in size.


3) Circle the large theropods on the cladogram.
4) Are the large theropods more closely related to each other than they are to the small theropods? Explain your answer.

5) Therefore, what is the best explanation for the similarities between large theropods?




Part 1: Predictions

Birds are well-adapted to flying, since many of their characteristics allow them to successfully fly. Examples of these characteristics include feathers, hollow bones, and long arms.


1) What evidence would you look for in the fossil record to determine if birds’ special characteristics evolved specifically for flight?

2) What evidence would you look for in the fossil record to determine if birds’ special characteristics evolved for other purposes and then were much later used for flight?



Part 2: Evidence

Below is a chart showing characteristics of some theropod dinosaurs. Archaeopteryx and moderns birds both achieved flight.







Hollow Bones

Feathers

Long Arms

Carnotaurus

yes

no

no

Tyrannosaurus

yes

yes

no

Velociraptor

yes

yes

yes

Archaeopteryx

yes

yes

yes

Modern Bird

yes

yes

yes

3) On the cladogram below, label the location of the appearance of each of the 3 characteristics given in the chart above.




4) Did hollow bones evolve before or after flight? before after


5) Did feathers evolve before or after flight? before after
6) Did long arms evolve before or after flight? before after

Part 3: Conclusions

7) Based on the evidence, determine if birds’ special characteristics evolved specifically for the purpose of flight. Explain your answer.

8) Two students are debating why feathers evolved.
Student 1: Feathers evolved before flight did, so they evolved for another purpose. They just happened to be useful for flying later on.
Student 2: But what good are feathers if the animal can’t fly? I think that dinosaurs evolved feathers with the eventual goal of flying.
With which student do you agree? Why?
9) Besides flight, what is another use of feathers?

10) Does evolution happen with a goal in mind? In other words, is there a specific direction evolution takes to reach a pre-determined end result? Explain your answer.

11) Given what you now know about convergent evolution and flight evolution, how many times did flight evolve in Archosauria (including dinosaurs, crocodiles, and pterosaurs)? How about in Tetrapoda (animals with four limbs)? Give examples explaining your answers.



Part 1: “Missing Links”

The Archaeopteryx is often called a “missing link” or transitional fossil, in that its appearance is transitional between dinosaurs and modern birds.


1) What are 2 characteristics of Archaeopteryx that are similar to non-avian dinosaurs?

2) What are 2 characteristics of Archaeopteryx that are similar to modern birds?

3) Why is the Archaeopteryx considered to be a “missing link” fossil?

The discovery of one “missing link” fossil creates two additional gaps – in this case, one between dinosaurs and Archaeopteryx and the other between Archaeopteryx and modern birds. We will examine the second gap, between Archaeopteryx and modern birds, and birds that fill that gap. The chart below shows characteristics of some of these birds.







Archaeopteryx

Confuciusornis

Enantiornis

Ichthyornis

Modern Birds

Feathers

yes

yes

yes

yes

yes

Fused tail bones (pygostyle)

no

yes

yes

yes

yes

Fused wrist and hand bones (carpometacarpus)

no

no

yes

yes

yes

Fully folding wing

no

no

yes

yes

yes

Fewer vertebrae for a more rigid body

no

no

intermediate

yes

yes

Fused pelvis for a more rigid body

no

no

no

yes

yes

Loss of teeth

no

no

no

no

yes

4) Did all modern bird features appear together or are there transitional fossils with a mixture of Archaeopteryx and modern bird features? Give two examples supporting your answer.


5) Why could Confuciusornis, Enantiornis, and Ichthyornis be considered transitional fossils?

Part 2: Driving Forces of Bird Evolution
6) A rigid body is strong and lightweight. How is this adaptation potentially useful for birds?
7) How could fused tail bones be preferable to a long bony tail for birds?
8) Based on the information on the chart on the previous page, how did the wing and bones in the wing change over time? How might these changes have been useful for birds?
9) The foot of the Enantiornis was equipped with a first digit directly opposite the other three digits. What can we infer about where they spent their time?
10) From Question 9 above, what does this tell us about whether or not flight was an integral part of their lifestyle?
11) Based on the changes observed in fossils, what appears to have been a key driving force in the evolution of birds? Explain your answer.



Part 1: Dinosaur and Living Animal Comparisons

Thermoregulation is regulation of temperature. The table below compares living animals with dinosaurs in terms of evidence for endothermy (the ability of animals to regulate their own temperature) or ectothermy (the use of external heat sources to regulate temperature). Birds today are endothermic and crocodiles are ectothermic.




Modern Birds

Crocodiles

Small Theropods

Ankylosaurs

Hadrosaurs

Sprawled stance which reduces air in lungs when running

No

Yes

No

No

No

Anatomy indicates extremely active lifestyle

Yes

No

Yes

?

?

Secondary palate which allows breathing and eating at the same time

Yes

Yes

Yes

Yes

Yes

Four-chambered heart to supply brain with a constant supply of oxygen-rich blood

Yes

Yes

Probably

Probably

Probably

Large brains, possibly to control higher levels of activity

Yes

No

Yes

No

Intermediate

Rapid growth rate of juveniles

Yes

No

Likely

?

Likely

Growth lines in bones possibly indicating annual cycles instead of constant growth

No

Yes

Yes

?

?

Found in polar regions

Yes

No

Yes

?

Yes

Insulating covering of hair or feathers

Yes

No

Yes

No

No

Similar temperature between core and extremities as measured by 18O:16O

Yes

No

Yes

Intermediate

Intermediate

1) Why does the table compare dinosaurs to birds and crocodiles as opposed to other animals living today?


2) Are all three dinosaurs the same as each other, or are there differences between the groups? Give 2 examples in your answer.
3) Do the dinosaurs match exactly with either birds or crocodiles, or are there differences? Give 2 examples in your answer.
4) Based on the comparisons, do you think small theropods were endothermic like birds today, ectothermic like crocodiles, or had a metabolism that was somewhere in between? Explain your answer.
5) Based on the comparisons, do you think ankylosaurs were endothermic like birds today, ectothermic like crocodiles, or had a metabolism that was somewhere in between? Explain your answer.
6) Based on the comparisons, do you think hadrosaurs were endothermic like birds today, ectothermic like crocodiles, or had a metabolism that was somewhere in between? Explain your answer.
7) Based upon the comparisons, do you think that all non-avian dinosaurs had similar metabolisms? In what ways might they have differed?
Part 2: Dinosaur Activity

Thermoregulation can be tied to levels of activity in animals today. Because endothermic animals produce more energy, they are able to sustain high levels of activity for extended periods of time, while ectothermic animals cannot exert maximum energy for long periods of time.


8) Some depictions of dinosaurs show them as slow-moving, “cold-blooded” animals, similar to crocodiles. Evaluate this view.
9) Some depictions of dinosaurs show them as active, constantly-moving animals, similar to birds today. Evaluate this view.

You are the science advisor to a movie being made about dinosaurs. Four scenarios are described to you as possible scenes in the movie.


Scenario A: Allosaurus attacks the sauropod Brachiosaurus. Brachiosaurus defends itself in a dramatic battle.
Scenario B: A Triceratops uses its three horns to successfully charge and kill the hadrosaurid Lambeosaurus, which it then starts to eat.
Scenario C: A sabertooth cat pounces on a Stegosaurus, but is unable to pierce its skin with its long, sharp teeth and eventually gives up.
Scenario D: A Velociraptor attacks the ceratopsian Protoceratops. The Protoceratops fights back.
1) Based of your knowledge of when different dinosaurs lived, which scenario(s) is/are not possible? Explain your answer.

2) Based on your knowledge of what different dinosaurs ate, which scenario is not possible? Explain your answer.

3) Based on your knowledge of what other animals lived with dinosaurs, which scenario is not possible? Explain your answer.

4) Therefore, as science advisor, which scenario do you recommend be included in the movie because it is most scientifically accurate? Explain your advice to the movie producer.






Part 1: Proposed Extinction Causes

The list below contains just a few proposed causes for the extinction of the dinosaurs.


A. Biting insects carrying diseases that killed dinosaurs over millions of years.

B. Changes in the DNA of dinosaurs causes scrambled genes.

C. Competition with mammals, who outcompeted dinosaurs for niches and/or ate their eggs.

D. The evolution in plants of substances poisonous to dinosaurs.

E. Falling sea level produced loss of habitats.

F. Impact of an asteroid.


1) What evidence in the fossil or rock record (if any) would each of the proposed causes leave behind?
A:

B:

C:



D:

E:

F:



Part 2: Testing the Extinction Causes

The proposed causes must explain all the events associated with the extinction.


2) Based on the evidence you determined in Question 1, how would you test (if possible) the proposed causes of the extinction? For example, what animals would be affected and what patterns would be observed?
A:

B:

C:



D:

E:

F:


3) Summarizing your answer to Question 2, what proposed causes are testable by looking at the fossil and rock record?
A B C D E F
4) The extinction was geologically abrupt and not gradual. Based on this information, what proposed causes would be eliminated? (Put an X through what can be eliminated)
A B C D E F
5) Animals (both on land and in the ocean) other than dinosaurs went extinct. Based on this information, what proposed causes would be eliminated? (Put an X through what can be eliminated)
A B C D E F
6) Overall, which of the proposed causes can be tested and is best supported by the evidence?
A B C D E F
Explain your answer.




 Kortz, 2009 Lecture Tutorials for Dinosaurs: A Concise Natural History


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