Dinosaurs Midterm

Sedimentary Rocks

1. Made of eroded pieces of rocks

2. Often buries organisms and creates fossils

3. Can tell the relative ages of these rocks

4. Collected in low-lying areas transported by wind, water, gravity, or ice

Igneous Rocks

1. Forms from melts that cool and solidify

2. Can tell the absolute ages

3. Rarely preserves fossils

Metamorphic Rocks

Form due to heat and pressure

Examples: Slate, Schist, Marble, Quartzite

Body Fossil

part of an organism 

Trace Fossil

evidence of an organism’s activity

• trackways/footprints, feces/coprolite, eggs, nests, burrows

Oldest definitive fossils

Stromalites in Western Australia ~ 3.5 billion years ago; bacterial body fossils

Isotope

Different variant of an element based upon number of neutrons

• Carbon-12: 6 protons, 6 neutrons

• Carbon-13: 6 p, 7 n

• Carbon-14: 6 p, 8 n 

*Two kinds of isotopes: stable and unstable (unstable parent changes into stable daughter)

Concept of deep time

• Coined by James Hutton (18th century)

• Idea that life has no record of beginning and no prospect to end

Geologic Time Scale

End-Permian extinction

Greatest mass extinction in history of life; ended around 80% of all species and 60% of genera (genuses)

Caused by the (1) formation of Pangaea and (2) volcanic eruptions

What specific influences during the formation of Pangaea caused the end-Permian extinction?

• Severe decrease in shallow marine environments

• new competition from invaders

• low sea level

• new ocean circulation and weather patterns

• drier continents

What specific influences from volcanic eruptions caused the end-Permian extinction?

• Presence of acid rain and pollution

• CO2 released (global warming)

• Acidification and anoxia in oceans

• Ozone depletion

The Scientific Method

1. Observe

2. Hypothesize

3. Predict

4. Test Predictions

   1. Be open to finding evidence to refute predictions

Darwin’s contributions to the theory of evolution

• All organisms have a single common ancestor

  • Common Descent with Modification (over time)

• Natural Selection

• Artificial Selection (variation under domestication (like wolves turning to dogs))

Natural Selection

A mechanism that explains evolution

Others include sexual selection, genetic drift, historical contingency, group selection, etc.

Eukaryotes

Organism that has clearly defined nuclei and organelles surrounded by plasma membrane (specifically have mitochondria and chloroplasts)

Origin of mitochondria and chloroplasts

Added through the process of ENDOSYMBIOSIS for energy and protection

Transfer of function of gill arches

1. Used for filter feeding

2. Respiration

3. Function then made for jaws + respiration

** Human embryos also have gill arches

Sarcopterygii

Fleshy-limbed “fish”

Actinopterygii

Ray-finned “fish”

Gnathostome

Vertebrates with jaw mouths

Tetrapods

Vertebrates with four limbs and digits to walk on

Two types: Amphibians & Amniotes

Two types of Amniotes

Synapsides (and mammals) and reptiles (and birds)

Amniotes’ evolutionary novelties

1. Amniotic/self-contained eggs with membranes

2. Internal fertilization

3. “Waterproof skin” 

4. Complex lungs

Tetrapods’ evolutionary novelties

1. Four limbs with digits

2. Vertebrae with struts

3. Robust hips attached to spine

4. Stapes (bone connecting eardrum to inner ear)

   1. transfer of function from when it once was the upper jaw turned into the brain case

Diapsid

organisms that have two temporal fenestra

Synapsid

organisms that have one temporal fenestra

Anapsid

organisms that have no temporal fenestrae

Archosaur

Popular in most of the Mesozoic time period after the end-Permian extinction

Examples: crocodiles and relatives, Pterosaurs, Dinosaurs (including birds)

Traits of Archosaurs

1. Thecodonty

2. Antorbital fenestra

3. Mandibular fenestra

4. Parental care

Ornithodire

Two types: Pterosaurs & Dinosaurr

Evolutionary novelties of an ornithodire

• Mesotarsal Ankle

  • ankle bone fused tibia and fibula together

  • limited range of motion in the ankle

• Digitigrade foot posture

  • ankles off the ground when walking

  • organisms walk on digits/toes

  • longer limbs, making them more lithe and fast

Pterosaur

Winged reptile and archosaur

Dinosaur

Meaning “terrible lizard” as of 1842; coined by Richard Owen (1804-1892)

• is a type of ornithodire and archosaur

• extinct after the end-Cretaceous period

Temporal Fenestrae

Holes in the area behind the eyes in a skull

Antorbital fenestra

Holes in the area between the eyes and the nose of a skull

Mandibular fenestra

Holes in skulls near the mid-jaw

Monophyletic Groups

Ancestor + ALL descendants shown on a cladogram

• is good because it shows complete branches on an evolutionary tree

• no characters are cut out, some are just grouped together separately

Paraphyletic Groups

Ancestor + SOME descendants shown on a cladogram

• is bad because it shows artificial, incomplete branches on an evolutionary tree

• gives the false impression that non-groups exist

Polytomy

On a cladogram/phylogenetic tree where a single node branches into more descendant lineages

Convergent attributes

Attributes/characteristics not attained through biology, but through the function of that characteristic - is unrelated to the fact that another organism might have the same characteristics 

Homologous attributes

Attributes/characteristics attained within an organism due to a common ancestor that also had that characteristic (biologically passed down, and therefore may be seen in other differing organisms)

Secondary loss

Evolutionary novelties in organisms lost over time/generations

Example: whales have a pelvic bone deep in their tissue, but its growth is stunted and not used

Sister group

Group most closely related to another shown on a cladogram

Mesotarsal ankle

Ankle bone fused with tibia and fibula found in ornithodires

• promotes a limited range of motion in the ankle because of stiffness 

Various foot postures

1. Plantigrade

2. Digitigrade

3. Unguligrade

Dinosaur evolutionary novelties

1. Erect posture

2. Narrow tracked gait

3. Opening in hip socket bordered by a bony upper lip

4. Upright femur with inturned head

Relative Dating

age of rocks compared to other rocks

Relative dating principles

1. Original horizontality (Steno)

2. Lateral continuity (Steno)

3. Superposition (Steno)

4. Cross cutting relationships (Hutton)

   1. Faunal Succession (Cuvier)

Absolute Dating

age of rocks in years; based upon radioactive decay of atoms within mineralsHal

Half life

Time required for ½ of the radioactive parent to decay into its daughter product

Radioactive decay

One element (parent) changes into another (daughter) with a more stable configuration

• neutrons from the parent will leave through half-lives to create a daughter product, changing the atomic nuclei

Relative dating methods

1. Biostratigraphy

   1. Use fossils to correlate rocks and determine their ages

2. Lithostratigraphy

   1. Correlating rock types (sandstone with sandstone)

   2. Often combined with biostratigraphy