Review course policies, syllabus.

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 evidence

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 researchers!

Dinosaur fossils have been found in Mesozoic Era rocks from every continent, including Antarctica.

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 Owen:

• 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 "terrible lizard"

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 common ancestor.

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?
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 the hypothesis)
• 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 fewest assumptions)
  • 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!), unicorns, dragons, etc.).

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 explanations included:

• "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 spontaneous generation)

Nicholas 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 by fossils?

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:
  • Palaeotherium, an early relative of tapirs and horses
  • Megatherium, a giant ground sloth
  • Mastodons and mammoths
  • The "Great Animal of Maastricht", a giant marine reptile eventually recognized by Cuvier as a huge sea lizard, and now named Mosasaurus: the first giant fossil reptile known to Science!
  • Other marine fossil reptiles, such as long necked Plesiosaurus and dolphin-like Ichthyosaurus
  • The flying reptile Pterodactylus

The stage was set for the discovery of dinosaurs.

To Next Lecture.
To Syllabus.

Last modified: 15 August 2012