GEOL 104 Dinosaurs: A Natural History
Fall Semester 2013
Introduction: What are Dinosaurs? What is Science? The Meaning of Fossils
Review course policies,
Goals of this course:
- Use dinosaurs as means of introducing students to key concepts of natural historical sciences, especially
evolutionary biology and historical geology
- Demonstrate the scientific method as it is employed to test questions about the paleobiology, behavior, and
extinction of dinosaurs
- Use the Dinosauria as a model of demonstrating patterns of evolutionary divergence and adaptation
Learning Outcomes: By the end of the semester, every student should be able to:
- Identify the major clades of dinosaurs and their primary attributes (anatomy, behavior,
stratigraphic and geographic distribution, etc.)
- Interpret cladograms in determining evolutionary relationships and distribution of specializations
- Assess claims of inferred dinosaurian behavior, physiology, and extinction patterns from fossil
Dinosaur science is NOT Archaeology!
Paleontology, the study of ancient life and their remains (fossils).
Fossils (from Latin fossilium "that which is dug up") are the physical remains
of past life and its activities preserved in the rock record.
Vertebrate Paleontology, the study of ancient backboned animals, including dinosaurs.
The majority of paleontologists, or even of vertebrate paleontologists, are NOT
Dinosaur fossils have been found in Mesozoic Era rocks from every continent, including
Types of dinosaur fossils:
- Isolated bones and teeth
- Skeletons, in varying degrees of completeness
- Footprints and trackways
- Skin impressions and Feathers
- Mineralized soft tissue (muscles, intestines)
- NON-mineralized soft tissue!!
- Eggs (some with embryos) and nests
- Coprolites (fossilized feces)
The word "Dinosauria" (and hence "dinosaur") was coined in 1842 by Sir Richard
- Greek deinos "fearfully great" (i.e., not just big, but SCARY BIG!), and sauros "lizard"
- Note: hundreds of books to the contrary, Owen did not say Dinosauria meant
Owen recognized 3 different dinosaurs:
- carnivorous Megalosaurus
- herbivorous Iguanodon
- armored Hylaeosaurus
Saw that they were different from other fossil (and modern) reptiles because of:
- upright limbs
- extra hip vertebrae
- and a few other skeletal features
Dinosauria is now recognized as a single major group of organisms, all descendants of a
Modern Definition of Dinosauria:
The concestor (most recent common ancestor) of Megalosaurus and Iguanodon
and all of its descendants
Thus, dinosaurs are not just "any fossil animals"
or "all fossil reptiles" or "all fossil reptiles of the Mesozoic" or "all giant fossil
reptiles of the Mesozoic." Instead, they are specific branch of the Tree of Life.
What is Science?
- Is NOT simply a body of knowledge
- Is the empirical (evidence-based) way of understanding the natural universe
- Uses the method of framing and testing hypotheses
- Proceeds by publication of ideas
- Allows others to check the original scientist's observations
- Allows others (including later generations) to independently test the hypotheses
- Allows ideas to be widely transmitted
The following (from Thomas Kida's Don't Believe Everything You Think) are a useful set of characteristics of thinking like a scientist:
- Keep an open mind, but be skeptical of any unsubstantiated claim
- Make sure a claim (hypothesis) can be tested
- Evaluate the quality of the evidence for a claim
- Try to falsify the hypothesis (i.e., look for discomfirming evidence)
- Observations of natural phenomena lead to possible explanations (hypotheses)
- These hypotheses must be falsifiable (i.e., there must be some test, experiment, or
observation which can demonstrate that the hypothesis is untrue)
- Until the hypothesis is tested, it is only considered a speculation
- If the hypothesis survives a test (or tests) of falsification, it is tentatively (or
provisionally) accepted (keeping in mind that additional tests might potentially overturn
- Consider alternative explanations
- Other things being equal, choose the claim that is the simplest explanation for the phenomenon (i.e., the one that requires the
- This is formally known as the principle of parsimony, and also called Occam's razor
- Other things being equal, choose the claim that doesn't conflict with well-established knowledge
- This is sometimes refered to as the principle of consilience
- Proportion your acceptance of a claim to the amount of evidence for or against a claim
The Meaning of Fossils
Dinosaur fossils have been weathering out of the rock since LONG before humans evolved,
yet "Dinosauria" was not recognized until 1842. Why did it take this long?
Before scientists could recognize the existence of dinosaurs, they had to recognize that
fossils were the remains of dead (not alive), unknown, extinct (not living anywhere) organisms.
Traditional cultures around the world noticed fossils, but assumed they were remains of
supernatural creatures (giants, trolls, mammuts (a Siberian [Yakut] legendary race of
"earth dwellers": the name is now transferred to fossil elephants!),
During the Renaissance and Enlightenment in Europe, many thinkers began to abandon a view
of the mythic past that included monsters and dragons. So what might fossils be? Some
- "Lessons" put there by God, or "tricks" by Satan
- "Sports of nature": rocks that just happened to look like animal and plant parts
- Products of the "vital force"
of nature (at this time, many people believed that living things were produced by
Nicolas Steno, a 17th
Century naturalist, came up with a simple solution: fossils really WERE parts of
dead animals and plants! Steno was one of the first people to recognize that rocks were
not eternal, but were formed during the history of the Earth. So fossils were the remains
of living things buried as those rocks formed. But what sort of animals were represented
Baron Georges Cuvier
(France) and contemporaries examined many fossils in the late 1700s/early 1800s:
- Had access to a wide variety of modern animal specimens as well as fossils
- Developed comparative anatomy: detailed descriptions of the equivalent parts of
different living things
- Recognized fossils were remains of unknown organisms: that is, they were not
examples of known living species
- Explained them being unknown because they were extinct organisms
- Examples of unusual extinct vertebrates described by Cuvier and contemporaries in the
late 1700s and early 1800s included:
The stage was set for the discovery of dinosaurs.
To Next Lecture.
Last modified: 26 August 2013