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Lecture 1: What is a Dinosaur (3/31)

The big question of the day: What is a dinosaur?

Pterosaurs, flying “dinosaurs,” are not considered a scientific dinosaur
Dimetrodon, a synapsid, is not considered a scientific dinosaur

Defining dinosaurs

Dinosaurs: Greek, “dino” = terrible, “saur” = lizard
Enormous in size, legs like elephants (thick, heavy leg, not quite a ball and socket joint)
Defined in 1842 by Richard Owen
By looking at the jaws and details of bones, you can infer whether or not it is a reptile.
“Principle and best-established representatives” Megalosaurus, iguanodon, and Hylaeosaurus all share similarities.
Binomial nomenclature: formal way scientists name organisms.
Structure of Binomial nomenclature: Genus species (Tyrannosaurus Rex)
Closely related species share the same genus name but have different species names.
Example: Triceratops prorsus, and Triceratops horridus
Megalosaurus: Greek ‘megas’ = great,’sauros’ = lizard
Iguanodon: ‘iguana’ + greek: ‘odon’ = tooth
Hylaeosaurus: Greek: “hylaios” = of the forest, ‘sauros’ = lizard
As science has gotten more diverse, so have dinosaur names
The original definition grouped the organisms together based on similarities in their skeletons.
“Dinosauria” represented a distinct tribe grouped together for convenience.
Dinosaurs share relationships; they have common ancestors.

Clade: Grouping of organisms that share an evolutionary common ancestor.
As time passes, organisms such as subclades continue to diversify.
Synapomorphy: A derived trait could be shared in many species that do not have an MRCA.

Perforate acetabulum allows dinosaurs to stand up straight and have that elephant-like leg.
Dimetrodon (Not a Dinosaur!)
Greek: “di” = two, “metre” = measure, “odon” = tooth

Synapsids (Mammals): One hole behind the eye socket
Diapsids (birds and reptiles): Two holes behind the eye socket
Both groups have skulls that are built differently
Dimetron is considered not a dinosaur because it shares a synapomorphy with mammals.
Conclusions:
Lifeforms are organized into clades
Clades are defined by synapomorphies
Not all prehistoric animals are dinosaurs
Dinosaurs are a unique group of animals that share a common ancestor

Lecture 2: Science (4/2)

Oviraptor, Greek: ‘ovo’ = egg’ and ‘raptor’ = thief
Small theropod (meat eating dinosaur) with unusual morphology (had no teeth)
Morphology: Physical structures and form of an organism
Found on top of a protoceratops (not actually this) (it was protecting its own eggs) nest
Had attachments for a beak
Feathered dinosaurs discovered in late 1990s
Close relatives of Oviraptor are found with pygostyles (Tail bones fused together to anchor feathers)
Empirical: Things that can be recognized by the senses (sight, touch)
Law: A generalization about some aspects of the natural world that appears to be true in all cases
Hypothesis: Proposed explanation for a set of observations of the natural world
Theory: An explanation about some aspects of the natural world. Repeatedly tested and confirmed.
All science ideas are subject to be replaced
Using methodology, we gain a better understanding of the empirical world over time.
Hard to test hypotheses on dinosaurs.
Hypotheses are grounded in science but not truly scientific
How is science different from other ways of knowing?
It is empirical (unlike law, logic, mathematics)
It is falsifiable (unlike many psychological and social theories)
It is progressive (unlike art)
How is science similar to other ways of knowing?
Science is normative: the culture dictates how observations are interpreted and what questions are worth asking.
Ethical issues in paleontology!
Historically, paleontology is closely linked to colonialism and resource extraction
Used to justify land dispossession

In some cases, DNA and/or proteins can be preserved in fossils
The oldest broadly accepted DNA comes from a 1 million-year-old mammoth in Siberia; the oldest proteins come from a 3.8 million-year-old ostrich egg.
Scientific journal: A specialized publication for evaluating and sharing scientific research between scientists
Peer review: A process used in journals, multiple scientists will argue for the publication or rejection of an article.
Corroboration: When multiple studies/techniques support the same hypothesis. Corroboration is a critical part of theory building.
Room for counterarguments

Lecture 3 Science (4/7)

Fossil: The preserved remains of a prehistoric organism
There is no easy distinguishing line when something gets buried under rocks
Most sedimentation occurs along coastal regions
There are more fossil records of shallow marine organisms than we do of dinosaurs
Most animals don't survive the process of fossilization
How does fossilization occur? Organisms must be buried under sediment on land,and erosion (lost of sediment) is more common than sedimentation.
Most skeletons are a mixture of organic and inorganic materials
Minerals: Solids with a well-defined chemical composition and crystalline structure
Minerals are the building blocks of rocks
Bones, teeth, and shells are unusually resistant to destruction and decay
Less mineralized structures are less likely to fossilize
Hydroxyapatite: In vertebrates, the main mineral in their bones
Teeth have a higher mineral concentration and are more likely to preserve
Hydroxyapatite reacts with other minerals, especially if there's water. This can lead to the dissolution of the original material and replacement by inorganic minerals
The older the fossil, the more likely it is to exhibit complete replacement.
Body Fossil: Physical remains of an organism
Very rare to find whole intact skeletons, usually fragmented or damaged.
Trace Fossil (ichnofossil): Remains of an organism but not the organism itself
Such as footprints, poop, bite marks
Provide evidence of prehistoric behavior.

In some cases, DNA and/or proteins can be preserved in fossils
The oldest broadly accepted DNA comes from a 1 million-year-old mammoth in Siberia; the oldest proteins come from a 3.8 million-year-old ostrich egg.
Scientific journal: A specialized publication for evaluating and sharing scientific research between scientists
Peer review: A process used in journals, multiple scientists will argue for the publication or rejection of an article.
Corroboration: When multiple studies/techniques support the same hypothesis. Corroboration is a critical part of theory building.
Room for counterarguments
Molecular Fossils: DNA, proteins, lipids (Fats)
Bone Beds: Sites where hundred or thousands of fossils are preserved
Lagerstatte: A fossil deposit with exceptional preservation
Anoxic environments that preserve many individuals with evidence of soft tissue
Cretaceous-age Santana and Yixian formations, Myanmar (burmese) amber

Lecture 4 Paleontology (4/9)

Paleontology: The branch of science that deals with the discovery, collection, and preservation of fossils
Dinosaurs have been found on every continent, but they are not distributed evenly.
Sedimentation: Laying down of dirt and mud, eventually turning into layers or rock
Erosion: The weathering of rock by wind and water
Complex patterns of sedimentation and erosion mean rocks from different geologic ages are exposed in different parts of the world.
Stratigraphy: Science of mapping the order or rocks
Dinosaurs are found in Mesozoic rocks, because they are in the middle of the stratigraphic column.
Divide rocks into three major groups
Igneous: Formed through the cooling and solidification of magma and lava.
Sedimentary: Formed by the accumulation and cementation of sediment at the earth's surface
Metamorphic: Formed by the transformation of other rocks through extensive heat and pressure (marble is a good example)
Modern paleontology arose in Britain and traveled alongside European colonialism.
Mary Anning, one of the first paleontologists (seashells seashells by the seashore)

First dinosaurs discovered in Britain (1820-1850)
Dinosaurs “bone wars” in the US (1860-1880)
Major finds in Canada (DInosaurs Provincial park) (1890-1910)
American paleontologist study in the Gobi desert (china closes off) (1920-1930)
German paleontologist study Tanzania; French paleontologists study Morocco, ALgeria, and Madagascar (1910-1950)
Dinosaurs considered evolutionary failures

Lecture 5 (4/14)

Different layers of rock called Strata
Geology: Scientific study of the physical earth and its composition
The earth is Dymanic: Energy is continually moving through the planet
The founding principle of geology is uniformitarianism: Processes that operate today operated the same way in the past.
Radioactivity in the earths core generated convention, bringing magma to the surface that cools to igneous rocks
Heat and pressure eventually produce metamorphic rocks
Lithostratigraphy: (lithos means rock) dating rocks based on their order and mineral composition
Stratigraphic columns are maps that describe the vertical layering of rock in a particular location.

The law of superposition: In undeformed stratigraphic sequences, the oldest strata lie at the bottom, while the youngest strata are on the top. The deeper you go, the farther back in time you go.
Law of lateral continuity: Layers of rocks are continuous until they encounter other bodies that block their deposition.
Biostratigraphy B (bios = life): Dating rocks based on their fossils
Index fossils: Fossils from organisms that had a broad distribution but were short-lived
Geochronology: (geo = earth, chronos = time) provides absolute data for strata
Radioactive decay: The process where an unstable atom loses energy by radiation

Lecture 6 (4/16) Morphology

The scientific theory of common descent states that all living things are connected through a series of common ancestors
The scientific law of natural selection shows how populations become better adapted to their environment by the preservation of favorable traits
Variation
Competition
Adaptations
Selection
Push and pull of common ancestry and natural selection
Eoraptor, One of the oldest known dinosaurs
Autonomy gives us insight into what the first dinosaurs looked like (ancestral condition)
← anterior → Posterior
Dorsal (top of back)
Ventral (stomach)
Proximal, towards the body
Distal, away from the body
The earliest dinosaurs had very lightweight skeletons
Fenestra: holes
Orbit: eye socket
Antoribal fenestra
Naris: nostril
Mandibular fenestra
Kinetic Skull: (Cranial kinesis): significant movement of skull bones relative to each other. Ex: snake being able to eat animals larger than itself
The pelvis is made out of three bones: the ilium, ischium, and pubis
A hole in the pelvis the (acetabulum) allows the femur to lock in place and gave dinosaurs an upright stand like birds and mammals
Dinosaurs dont have a ball and socket join, femur bone had a barrel shape, restricting movement to forward and backward motion
Humerus vs tibia/fibula: ratio provides an approximation of speed
The earliest dinosaurs had five fingers on their hands, an ancestral condition of the tetrapods
Different clades of dinosaurs will go on to elaborate and/or lose these digits
Carnotaurus: Carnis = flesh, taurus: bull

Lecture 7 (skipped)

Lecture 8 (4/23) Paleoclimate and paleogeography

The Industrial Revolution in Great Britain is linked to its large coal deposits
Fossilized remains of vast swamps
Fossils preserved in carbon-rich (carboniferous) rocks contain plants and animals that could never survive in Britain today.
Wegener's continental drift hypothesis suggested that continents moved over time
Paleobiogeography: The distribution of where fossils are found over space
Provides line evidence for continental drift. Largely rejected at first because it lacked a mechanism.
The development of sonar submarines during World War II resulted in the exploration of the ocean floor exploration. Discovery of great rifts in the ocean.
In ocean rifts, magnetic minerals in newly forming rocks record of the direction and intensity of Earth's magnetic field.
Plate tectonic theory provides a framework for understanding these features.
Earth is dynamic: energy is continually moving through the planet.
Paleoclimatology: Is the reconstruction of climate through deep (geologic) time
Tillite: Sedimentary rock containing unsorted and unstratified rock material, Created by glacial deposition (cold)
Evaporite: Sedimentary rock formed from a deposit of precipitated minerals. Caused by the evaporation of saltwater (hot and dry) (Desertification)
Latorite and Kaolinite: Sedimentary rocks formed from the extreme weathering of parent rock. Requires hot temperatures and large amounts of water
Coal is evidence of large forests
Palm and mangrove fossils demonstrate a warm climate
Crocodilian fossils also constrain temperatures
Climate change: Avg global temperature
Pieced together using temperature proxies (paleo thermometers)