Key Points
- "Dinosaur" is not simply a term for any vanished giant reptilian creature. It refers specifically to "any member of Dinosauria".
- Dinosauria is a particular branch of the "reptile" (sauropsid) family tree. Not all dinosaurs were large, scaly, or even extinct!
- Living birds are the (only) surviving part of Dinosauria.
- Extinct dinosaurs are known only from their fossils (physical remains of their body parts or traces of their behavior preserved in the rocks), but these have been found on every continent.
- Through the study of dinosaurs, we can learn about: how rocks form; how environments and living things change through time; how animals behave, grow, and function; how parts of ecosystems interrelate; and how mass extinctions driven by large-scale rapid environmental changes can radically alter the diversity of life.
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
Some Basics
Dinosaur science is NOT archaeology! Archaeology is the study of human artifacts and remains; in contrast, the study of ancient life and its remains (fossils) is 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.
More specifically, the study of dinosaurs is a subset of vertebrate paleontology, the study of ancient backboned animals. 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.
There are many types of dinosaur fossils:
- Isolated bones and teeth
- Skeletons, in varying degrees of completeness
- Footprints and trackways
- Skin and feather impressions
- 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.
The Modern Definition of Dinosauria: The concestor (most recent common ancestor) of Megalosaurus, Diplodocus, 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.
In order to understand dinosaurs, we will have to explore various types of scientific information:
- What are rocks, how do they form, and how do they record environments of the past?
- What are fossils, and how do they form?
- How do we determine hold old rocks and fossils are?
- How do we use fossils to reconstruct the shapes of extinct animals?
- How does evolution work, and how can we use it to figure out the relationships of different organisms to each other?
Once we have understood these, we'll look at the dinosaurs themselves: where they came from; how the rose from small-bodied animals to being the dominant land animals; how the different groups lived, fed, and diversified; how they may have behaved, courted, raised their young; how (some of them) got so amazingly big; and whether or not they were "warm-blooded". We will look at the origin of birds, and how we can (and can't) use information from living birds to interpret the biology of dinosaurs. We will look at the contemporaries of dinosaurs, especially their flying cousins the pterosaurs, the various marine reptiles that swam the Mesozoic seas, the rise of our own group (the mammals), and the flowering plants. We will see how the Age of Dinosaurs came to an end, and how different lines of evidence are used to see how the extinction at the end of the Cretaceous happened.
But before all of that, we'll look at how the process of Science works, and then at how using that process our knowledge of dinosaurs has changed over the last two centuries.