Discovering Dinosaurs: Evolution, Extinction,
and the Lessons of Prehistory
||Recommended: The Evolution and
Extinction of the Dinosaurs
1 May 26 - June 1: Theropod Anatomy and Geneology
have long been a subject of fascination for both children and adults.
Part of their mystique is that they went extinct 65 million years ago.
But did they? This week Drs. Mark Norell, Sunny Hwang, and Diego Pol
introduce evidence that shows one group of dinosaurs did not go
extinct. They are related to such well-known dinosaurs as Tyrannosaurus
and Velociraptor, and today we call them birds. First, we look at the classification of this one specific
group of dinosaurs, the theropods. Then we look at the general body
plan of the extinct members of the theropod group and how their
features illuminate their possible behaviors. And finally, with these
clues, we begin to illustrate the link between birds and dinosaurs.
• Review the course orientation.
• Find out about the characteristics that define the group known as theropod dinosaurs.
• Understand why not all dinosaurs are extinct.
• Examine the study of cladistics, which uses taxonomic classifications to reflect the evolutionary history of a group.
• Identify the difference between non-avian and avian theropod dinosaurs.
• Evaluate the anatomy and physical characteristics for non-avian theropods.
• Begin to analyze the evolutionary relationships between theropod dinosaurs and modern birds.
* Read Chapter 9 (pages 107-110 only), Chapter 11 (pages 141- 149 only), and Chapter 13.
• Respond to the Discussion Question 1: Classification (Both cladistics and the traditional Linnaean classification method rely on characteristics to classify organisms. What do you think are some of the similarities and differences between the two methods of classification?)
• Respond to the Discussion Question: Theropods Dinosauria (As you've read, theropods are one group of dinosaurs. Name a few characteristics of this group. What do you think are some of the characters that distinguish theropods from all the other animals in the group Dinosauria?)
* Fossil Halls
2 June 2 - June 8: Fossilization and Collection of Dinosaurs
Most of what we know about extinct dinosaurs comes from the evidence we find in the fossil record. So learning where to look and spending time in the field looking for fossils is a large part of any paleontologist’s work. What is a fossil? Where do you find dinosaur fossils? Once you’ve found one, how do you retrieve and collect it? What can you learn from fossils? This week we answer these questions and more as we look at the tools and techniques paleontologists use when they are in the field and in the lab. We also go behind-the-scenes in the Museum’s vertebrate paleontology preparation laboratory to see how a specimen is prepared.
Discussion Question 1: Fossil Collecting: (Each summer Dr. Norell heads to the Gobi Desert on a fossil-collecting adventure with an expedition team. Some people may have more than one role on an expedition. Some people, like fossil preparators, may focus on only one job on the expedition. Imagine that you are joining the next trip to the Gobi. Which of the roles described this week would you be most likely to enjoy or be skilled at, and why? What do you imagine are the personality traits recommended for people who hold these roles?)
Discussion Question 2:
* Read Chapter 11 (pages 149-168 only) and Chapter 12.
3 June 9 - 15: Theropod Biology and Behavior
|Expectations||Amazingly, paleontologists know a bit about
how non-avian dinosaurs cared for their young, hunted for prey, and
even made sounds. How do they know? The fossil record contains some
clues—like the amazing specimen of an oviraptorid huddled over a nest
of its eggs, similar to how a chicken sits on its nest and the way
crocodiles build nests for their young. To study the behavior of
long-extinct dinosaurs, paleontologists not only study the fossil
record, but also get valuable insight from the behaviors of the living
descendents of non-avian dinosaurs, birds, and the closest living
relatives of dinosaurs—crocodiles. And finally we examine a
controversial topic— were non-avian dinosaurs warm-blooded or
* Recognize that there are shared behaviors between modern birds and crocodiles.
* Gain insight into the ways paleontologists make inferences about the behavior of long-extinct animals.
* Determine how evidence for the behavior of long-extinct animals can be found in the fossil record.
* Learn how the fossil record of theropod dinosaurs provides clues that help explain the diversity and behavior of modern birds.
* Examine how modern bird and crocodile behavior is similar to the behavior of non-avian dinosaurs.
* Study how scientists use fossil evidence to reconstruct the relationships between extinct species and modern species.
* Look at new evidence that some non-avian theropods were warm-blooded.
* Analyze a chicken or turkey skeleton to find several anatomical features common to both non-avian theropod dinosaurs and modern birds.
Discussion Question: Dinosaur Behavior: (As you read this week, some of what we know about the behavior of theropods is based on an analysis of the fossil evidence. In the case of theropod dinosaurs, some of the behavioral evidence is also based on our observations of their living descendants, birds, and their closest living relatives, crocodiles. Answer the following questions in the discussion:
What do you think are some of the problems with applying modern models to ancient organisms and their environment?
What do you think are some of the factors that allow you to apply a modern model and still get reliable information?
To what extent do you think scientists are reliably able to build a case based on fossil evidence, modern models, and inference?
How far can they go?
How do you think the cladistic method allows scientists to make these inferences in ways that other classification systems do not?)
Read Chapter 10 and pages 160-161 and 224-227.
* Rebuilding the lost world
* A world in transition
* Dinosaur vocalizations
* Crocodile sounds
* Red Gulch Dinosaur track site
* Cold blooded or warm blooded
* Were dinosaurs endotherms or ectotherms?
* Interpretting the Fossil Record
* Biases in the Fossil Record
* A collarborative system for sharing paleontological collections
* Ology - the Big Dig
* More on Morphology
* Are birds really dinosaurs
* Theropods and birds compared
|Week 4 June 16 -
June 22: The Origin
||We typically think of feathers,
a beak, a wishbone, and a breastbone as the essential characteristics
that define a bird. But in the last few decades, scientists have shown
that these features aren't unique to birds. How then do we describe
birds as a unique group? What is their evolutionary history? We first
examine each of the features that have traditionally been identified
with birds, and then trace the evolution of birds through their
150-million-year history. During this tour of bird evolution, we
highlight the most current knowledge about the features or characters
that define birds as a group, and then discuss the link between some of
these characters and the non-avian theropod dinosaurs.
Examine the characteristics traditionally used to describe birds.
Explore several milestones in the evolution from non-avian theropod to modern bird.
Determine the evolution of the features that enable birds to fly.
Grapple with possible reasons for the evolution of feathers, flight, and other bird characters.
Look at how modern birds fit into the maniraptor family tree.
Learn about the excavation and analysis of the dromaeosaur fossil known as "Dave."
Compare several anatomical features of a non-avian dinosaur and an avian dinosaur.
Hypothesize about the relatedness of an unknown specimen to an advanced non-avian theropod and a modern bird, using key characters. We typically think of feathers, a beak, a wishbone, and a breastbone as the essential characteristics that define a bird. But in the last few decades, scientists have shown that these features aren’t unique to birds. How then do we describe birds as a unique group? What is their evolutionary history?
Discussion Question: What's A Bird? (Until recently, if you wanted to determine whether something was a bird, you looked for the presence of feathers. Now that new evidence is revealing changes in their evolutionary history, the group known as birds is becoming harder to describe. It is now clear that some non-avian animals had feathers too. So, what do you think makes a bird a bird? How do fossil discoveries like "Dave", Mei long, and the nesting oviraptor make us think differently about this question?)
Read Chapter 9 (pages 114-124 only), Chapter 10, and Chapter 14 (pages 207-223). Be sure to look at the cladogram on page 208.
* Theropods compared
* Are Birds really dinosaurs
* China's feathered dinosaurs
* What is a cladogram?
* Cladogram: questions and segments.
* Dinosaurs and Birds
* Vertebrate Flight
* Mei Long
* Sleeping dino
* Birds fight dirty
* Assignment: Cladogram Theropods compared images Theropods compared images #2
* Bone Bed discoveries
* where does Dave belong? or here? or here?
* Yale Peapody research
* Yale main cladogram
* image of cladogram
* questions and segments
* Fighting dinos
* Semilunate carpals
* Fossil of largest bird ever
June 23 - June 29: Dinosaur
|Let's now return to the mystery
that surrounds the extinction 65 million years ago of what we now know
was most, but not all, of the dinosaurs. The cause of the event is
still shrouded in mystery. This week we look at some of the proposed
theories to explain this massive extinction. In particular, we examine
the evidence for the two leading theories: a meteorite impact and
extensive volcanism. We look at the evidence that supports and refutes
these explanations, and begin to hypothesize about how the group of
theropod dinosaurs we call birds and other small animals survived this
mass extinction. Also: Please submit a rough draft of your final
For the past four weeks we've explored the 235 million year history of avian and non-avian dinosaur evolution using the cladistic method. We investigated the evidence ourselves with our dinners in Week 3 and in Week 4 we tackled where to place the unknown specimens on the cladogram in the Theropod Interactive assignment. (There is still time to complete this assignment!!) Based on our study of the available fossil record it looks like there is a clear evolutionary relationship from Theropoda to Aves, but we learned that coming up with a true definition of a bird is not all that easy since visible attributes like feathers and flight don't provide us with adequate characters to classify them as a separate group.
So now where do we go? Into one of the biggest unsolved questions of paleontology of course: what happened to all of the non-avian dinosaurs 65 million years ago?
Take a moment and think about answers to the following questions. How do we study the dinosaur extinction? What do you hypothesize as the factors involved in such an extinction? The answer isn't as simple as it seems, as we'll discover this week.The Discussion Question this week asks you to wrestle with the evidence presented in the Course Essays and text and settle on an explanation for the K/T extinction. Be sure to support your decision in the Discussion with evidence from these and any other resources at your disposal. As always, please let us know if you have any questions or concerns.
Discussion Question: Extinction: (Which of the theories for the Cretaceous/Tertiary extinction do you think is the most plausible, and why? Include all your thinking about how the known evidence does and does not support the theory.)
Read Chapters 3, 4, 5, and 6. Chapter 2 is also a recommended reading.
Explore the pattern of the disappearance of non-avian dinosaurs 65 million years ago.
* What killed the dinosaurs?
* Mass Extinction was swift
Review different theories for the Cretacious/Tertiary (K/T) extinction.
* What killed the dinosaurs - invalid hypotheses
Examine and evaluate the evidence for the two leading extinction theories: meteorite impact and volcanism.
* K/T extinction
* Evidence for the meteor extinction theory
* Volcanic Eruption
* Divisions of Paleontology
* Volcanism or Meteorite
* Goddard, P. "What else died out?"
* Effects of Extinction Events
6 June 30 - 6: Birds after the demise of their Theropod ancestors
|This week we come full circle
and review the evidence that links modern birds to non-avian theropod
dinosaurs. We look at the tremendous diversity of dinosaurs and birds
found in the fossil record. Where did the dinosaur lineage split, and
when do we find the first characters for Aves? We know that a split
occurred, but these days the divergence still raises more questions
than answers. Maybe birds aren't as special as we thought.
Discussion Question The Science of Paleo: (In many fields of science, a hypothesis is followed by a series of organized experiments designed to test it. This is more difficult to do in paleontology, in which fossil finds determine the next advance in knowledge. And finding fossils, as Dr. Norell says, has a lot to do with luck. Earlier in the course, Dr. Norell said: "You never really know what you’ve got until you’ve done the analysis in the lab." How big a role do you think luck plays in this kind of scientific exploration? Paleontology is approached with the same rigor and held to the same standards as other scientific disciplines. What does this tell us about the nature of scientific inquiry and the field of paleontology?)
TEXT READINGS: The Mistaken Extinction by Lowell Dingus and Timothy Rowe Read Chapters 7, 15, and 16.
* DINO Directory
* Ology - the big dig
* Archaeopteryx - an early bird
* Final project
on Theropods & feathers
|Next Class: Genetics,
Genomics, and Genethics