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198 Cards in this Set

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Two types of dating life

1) Relative (based on order of events)

2) Absolute (precise dates)

Three Laws of Relative Dating

Superposition (old on bottom, new on top).

Law or Original Horizontality (strata deposited in horizontal layers).

Law of Original Continuity (strata deposits continue over lateral distances)

What is Biostratigraphy?

Subdividing geological time based on fossil content.

Types of Absolute Dating

Radioisotopes have different half-lives, allowing for specific dating.

1) C14 dating for organic fossils <60,000 years old

2) U/Pb dating of zircons (found in ash beds) for fossils >60,000 years old (this type uses rocks above and below to date.

What does Absolute Dating allow?

Dating of key fossil events, determine evolutionary rates, periodicity of extinction, etc.

Who proposed Continental Drift?

Alfred Wegner in 1912

Wegner's Proof for Continental Drift

1) Fit between continents, especially Africa and South America

2) Fossil distribution among South America, Africa, India, Antarctica, & Austrailia (Mesosaurus & Glossopteris)

3) Consistent ice-flow away from Gondwana's centre

4) Continuous mountain belts (Appalachians & Caledonides)

New Evidence for Plate Tectonics (1960s)

1) Mid-ocean ridge down Atlantic "fit" with continents

2) Ocean crust gets progressively older away from mid-ocean ridge (no crust older than 200 Ma, Jurassic)

3) Paleomagnetics showed continental movement

What is a Subduction Zone?

Oceanic crust being created (think conveyer belt with panels constantly being "made")

How are mountain belts formed?

1) Continent-Continent Collision

2) Subduction Zone (one plate slipping under another)

What is Gondwana?

Megacontinent of South America, Africa, India, Antarctica, and Australia

What are the 3 super-continents?

1) Pangea (300-200 Ma)

2) Rodinia (1200-800 Ma)

3) Nuna (2000 Ma)

How are Oceans formed?

1) Rift Valley through continent breakup (i.e. East Africa Rift)

2) Spreading produces a linear sea (i.e. Red Sea)

3) Becomes full ocean (i.e. Atlantic)

What is the Wilson Cycle?

Oceans are transitory features that are created as mega-continents break up and disperse, and are destroyed when continents collide.

Each Wilson Cycle takes 100s of millions of years

What is a Prokaryote?

Unicellular organisms that lack a cell nucleus or organelles (like chloroplasts, mitochondria).

What is a Eukaryote?

Unicellular or Multicellular organisms that have DNA in a nucleus, and contain organelles (like chloroplasts & mitochondria).

Carl Von Linne's Linnean Classification (1735-1758)

3 Superkingdoms:

1) Bacteria - Normal prokaryotes

2) Archea - Extremophile prokaryotes

3) Eukarya - All single & multi celled eukaryotes

Eukarya's Four Kingdoms

1) Protists - unicellular eukaryotes

2) Fungi - multicellular eukaryotes, absorb nutrients from dead or living, non-motile

3) Plants - multicellular eukaryotes (non-motile, photo-synthesizers)

4) Animals - multicellular eukaryotes (motile heterotrophs)

Kingdom Classification Hierarchy

1) Kingdoms, 2) Phyla, 3) Classes, 4) Orders, 5) Families, 6) Genus/Genera, 7) Species

Two Approaches to Species Classification:

1) Cladistics

2) Molecular Phylogeny

What is WIlli Hennig's (1966) Cladistics?

Clades are monophyletic groups (just one ancestor)

Does not include polyphyletic (i.e. corals) (more than one ancestor) or paraphyletic (i.e. reptiles) (common ancestors but not all descendants)

What do Cladistics recognize?

Three sets of morphological characteristics:

- Primitive (relating to original ancestral features = pleisiomorphies)

- Derived (first appear in the clade = apomorphies)

- Convergent/Analogous (similar features in unrelated organisms)

What is a Cladogram?

A Cladogram shows the order of the evolutionary appearance of derived characteristics. Shows sibling relationships (not ancestor-descendant).

Positives of Cladistics?

1) Rigorous & Testable

2) Can be used at almost any level of taxonomy

3) Can include fossil and living species in the same cladogram

What is Molecular Phylogeny?

Francis Crick discovered a measure for the degree of substitution in DNA, RNA, or proteins.

Molecules mutate at different rates, and molecular clocks can help measure origin of clades.

Pros & Cons of Molecular Phylogeny


1) Rigorous & Testable

2) Can be used at any level of taxonomy

3) Directly measures genetic differences


1) With rare exception, can only be used on modern organisms

What was life like in the Early Archean?

- Many volcanic islands, no true continents

- Faint young sun (80-85% of brightness, lots of CO2 in the atmosphere)

- Volcanic atmosphere with no oxygen

Three Steps in the Synthesis of Life

1) Formation of Simple Organic Molecules (Amino Acids, Nucleotides, Sugars)

2) Combination of Simple Organic Molecules into Complex Organic Molecules (DNA, RNA, Proteins)

3) Initiation of Replication (Reproduction)

Step One: Formation of Simple Organic Molecules (Amino Acids, Nucleotides, Sugars)

Miller-Urey Experiment: can create all basic amino acids, nucleotides, and sugars through volcanic gas x spark experiments.

*Reaction always works if anoxic (oxygen not present)

Step Two: Combination of Simple Organic Molecules into Complex Organic Molecules (DNA, RNA, Proteins)

- Agreed upon that DNA cannot be first

- RNA can replicate itself and act as a catalyst

- Recent studies have tried to prove that RNA can self-generate

Step Three: Initiation of Replication

1) Spiegelman Monster - experiment showing replication can form from RNA

2) Eigen performed same experiment with no

living organism seed, had similar results

*Think evolution in a test tube

What is the Martian Meteorite?

A 4 billion year old meteorite (ALH 84001) that had no conclusive evidence of life (organisms were incapable of holding genetic info to code life)

What is the 'Warm Little Pond' Theory?

Darwin believed that life formed in warm little ponds, like Hydrothermal Vents.

3 Clues supporting Hydrothermal Vents as source of Life?

1) The Great Bombardment - meteors in 3.8 Ga that would have sterilized upper oceans (deep sea vents would not be affected unless hit)

2) Chemical reactions require temperatures between 2-250 degrees celsius

3) Extremophiles are on the base of the tree of life, and were perfect for the conditions (hot acidic waters)

Where were the earliest fossils?

1) Warrawoona in Austrailia (3 Ga)

2) Barberton in South Africa (3.4 Ga)

What is the evidence for Warrawoona & Barberton?

1) Stromatolites - layers of unicellular organisms (occur today in Shark Bay, Australia)

2) Organic Microfossils - filaments & spheres of carbon that reflect the cell walls of unicellular organisms

When is the Age of Stromatolites?


What is Gunflint Chert?

A fossil on the north shore of lake superior (nearly 2 Ga), the most important early Proterozoic fossil

What is the Banded Iron Formation (BIF)?

Biological and sedimentary evidence implying that the Archean and Early Proterozoic oceans were full of dissolved iron, but that the oceans and atmosphere prior to 2.4 Ga contained essentially no free oxygen.

Anaerobic vs. Amphiaerobic

Anaerobic = cannot tolerate oxygen

Amphiaerobic = O2 if available, otherwise anaerobic


6*CO2 + 6*H20 = C6H1206 + 6*O2

Stages of Oxidation:

Stage 1: Iron Ocean (prior to 1.8 Ga)

Stage 2: Canfield Ocean (1.8-0.6 Ga)

Stage 3: Modern Ocean (after 0.6 Ga)

Stage 1 - Iron Ocean

- no free oxygen, and photosynthesis led to BIF

- huge deposits of banded iron formation

-oxygen oases formed near cyanobacteria, but quickly dissipated

Stage 2 - Canfield Ocean

- Some, limited, free oxygen

- Abundant H2S

Stage 3 - Modern Ocean

- Atmosphere + Shallow Ocean + Deep Ocean all Oxygenated

The Great Oxidation Event

- 1.8 to 2.4 Ga

- Transition from Iron Ocean to Canfield Ocean

- Corresponds with formation of Nuna

Results of The Great Oxidation Event

1) Disappearance of banded iron formation

2) Appearance of red-soils and river deposits (red beds)

3) Less Co2 allowed for ice age

4) Production of Ozone Layer to shield from UV

5) Permitted aerobic metabolism, allowing eukaryotes

What are Eukaryotes?

1) DNA is encased in the nucleus of the cell

2) Cells contain organelles (mitochondria, plastids)

3) Complex Morphology with spines & processes

4) Ability to change shape during life (cytoskeleton)

5) Can create complex multicellular units

What is Lynn Margulis' endosymbiosis?

Idea that Eukaryotes represent an endosymbiosis from prokaryote cells, between a) a fermenter (host cell), b) a purple bacterium (ancestral mitochondrium), and c) a cyanobacterium (ancestral plastid)

Types of Early Eukaryotes

1) Steranes - Archean, 2.7 Ga

2) Acritarchs - 1.6 Ga

3) Carbonaceous Compressions - 2.1 to 1.6 Ga

4) Fossil Red Algae - 1200 Ma (Brown & Green as well)

5) Oldest heterotrophs - 750 Ma

What is the connection between Rodinia & Kingston?

The Grenville Mountains in the Thousand Islands represent continental collisions that produced Rodinia

What was the 'Snowball Earth'?

The ice age after the break up of Rodinia between 730-580 Ma.

What were the three Neo-Proterozoic Glaciation episodes?

1) Sturtian Glaciation (740 Ma) - sponge biomarkers postdate this

2) Marinoan Glaciation (635 Ma) - Microscopic animals and embryos postdate this

3) Gaskiers Glaciation (580 Ma) - When life got big, with Ediacaran soft-bodied organisms

What were the oldest Ediacaran Fossils?

580 Ma Fronds from Mistaken Point, Newfoundland

These postdate the snowball earth by 2 million years.

The assemblage at mistaken point represents an extinct clade of rangeomorphs, extinct because they lack mouths and fed by suspension feeding

What is Dickinsonia?

Dickinsonia is an example of younger Ediacaran organisms, with this one having bilateral symmetry.

Found in Australia, Russia, and elsewhere.

What are Ediacaran organisms?

- Dolf Seilacher proposed that Ediacaran dics were benthic, not pelagic like Jellyfish

- Seilacher thought Ediacaran are similar enough to group into Vendobionta

- Regarded as an extinct kingdom or failed experiment

- Fronds of extinct clades showed tiering (suspension feeding)

- Extinct with Cambrian Explosion

- Some represented stem-group animals that further evolved

What was The Cambrian Explosion?

- The most profound and rapid diversification event (evolutionary radiation) in the history of life

- Mainly involves Bilateria ceolmates (ceolome = fluid filled cavity)

- Reflects the emergence of skeletons & brains

5 Types of Cambrian Skeletons

1) Crown-Group (Sponges)

i.e. Archeocyathan

2) Small Shelly Fossils (Molluscs)

i.e. Sclerites

3) Brachipods

4) Trilobites (Arthropods) - dominant cambrian group

5) Echinoderms & Chordates

3 Main Innovations of Cambrian Organisms

1) Vertical Dwelling Burrows

2) Systematic Meandering Burrows

3) Complex Deposit-Feeding Behavioirs

What is the Burgess Shale?

- A middle-cambrian shale near Field, B.C.

- The preservation of hard & soft-body marine life

- Key information about cambrian life

What caused the Cambrian Explosion?

1) Rise in Oxygen - latter part of the Ediacaran Oxygen Event

2) Ecological Feedback (Cambrian Arms Race + Agronomic Revolution)

What is DNA?

The genetic information of an individual organism that is coded in a series of nucleotides.

What is the Gene Pool?

The total amount of genetic information coded on all the individuals in the population.

What is Mutation?

The process in which one or more nucleotides in DNA changes.

What is Natural Selection?

The process of species evolving through better competing for food, living space, mates, and the avoidance of predators.

Improves the level of mutation and evolution.

What is the Pepper Moth?

The Pepper Moth is the example of natural selection, where speckled versions before 1880 were 99% of population, but with soot-blackened trees after 1880, they became 99% black.

After 1960 Clean Air Act, 50-50%.

What are Darwin's Finches?

Darwin's finches were a single generalized species of finch that reached the Galagos Islands.

They diversified into 14 species based on island and feeding strategy

What is Anagenesis?

The continual evolution of species until it becomes a new species


The splitting of one species into two as different populations respond to changing circumstances differently.

What is Convergence?

When similar life habit in a similar environment leads to the evolution of similar morphology among organisms until they are unrelated

i.e. Wings, that have been evolved by my many clades (analagous structures)

What is Co-Evolution?

Organisms evolving as a response to changes in their environment, but also in response to evolutionary changes in other organisms.

What is an Evolutionary Arms Race?

An example of Co-Evolution, where predator and prey adapts to compete.

What is Mutualism?

An example of Co-Evolution, where two species evolve to benefit both species.

What is the Van Valen's Law?

The Red Queen Effect. Any evolutionary advancement in one species forces the rapid evolution of all species that depend on it, otherwise a species will go extinct.

What is Anomalocaris?

A top carnivore found in the Burgess Shale, with shrimp, jellyfish, and arthropod parts!

What is a Supercontinent Cycle?

A billion year cycle, with 4 major intervals of glaciation, three of which correspond to supercontinents.

1) Early Proterozoic, 2 Ga = Nuna

2) Late Proterozoic, 1 Ga = Rodinia

3) Late Paleozoic, 300 Ma = Pangea

What are Greenhouse-Icehouse Cycles?

Al Fischer recognized fluctuations between greenhouse and icehouse conditions.

Greenhouse = warm, high seas

Icehouse = cold, low seas

3 Ways to Recognize Shift from Greenhouse to Icehouse

1) Leaf-Shape Analysis - smooth margins = tropical, serrate margins = polar

2) Oxygen-Isotope Analysis = Seawater oxygen reflect ice cap size = proxy for temp

3) Community Analysis = mummified fossil forest

What is Milankocitch Cyclicality?

Cycles relating to Obliquity, Precession, Eccentricity

Sepkoski's Evolutionary Faunas

Phanerozoic marine animals are divided into 3 categories:

1) Cambrian Faunas - trilobites, mud grubbers

2) Paleozoic Faunas - Armoured filter feeders, pelagic predators, during the Ordovician radiation (ecological tiering) (cephalopods = top carnivore)
3) Modern Fauna - Gastropods, bony fish

How can Modern Fauna be less armoured and more mobile?

1) Predation = mobile swimmers, enhanced ability to break shells

2) Biological bulldozing = can burrow deep

What is a Mass Extinction?

A significant and geologically instantaneous drops in diversity.

Hierarchy of Mass Extinction:

1) Major = >50% of family extinction

2) Intermediate = 10%-50% family extinction

3) Lesser = 3-10% family extinction

*mass extinction is probably equal to natural selection in controlling the evolution of life on Earth

What are Biogeographic Provinces?

Distinct biotas, primarily reflect geography and climate.

How do Plate Tectonics impact Climate?

1) Movement Through Climate Zones

2) Plate Seperation

What is the Simpson Similarity Index?

Measures the degree of similarity between two biogeographic provinces

What are Epeiric Seas?

Shallow seas.

Tidal Environments

Represent supratidal and intertidal flats with high salinity, little exposure to sunlight

What is the Tetradium Thicket?

Analogous to modern fringing reef

What is a Sub-Tidal Seafloor?

Seas with low salinity, exposure to sunlight.

What are Osteichthyes?

Bony fish.

What are Chondrichthyes?

Sharks & Rays.

Agnatha (Jawless Fish)

Early Cambrian craniates from the Chengjiang in China.

Slow, bottom-grubbing fish

Gnathostomes (Jawed Fish)

- Acanthodians = first jawed fish

- Chondrichthyes

- Placoderms

- Osteichthyes = tetrapods

What is the Origin of Tetrapods?

Mountain belts formed rivers and lakes that had freshwater in proximity to land, preserved in Old Red Sandstone.

Transitioned into amphibians = skull structure, spine, limb attachments, folded enamel of teeth

How did land plants evolve?

Through Green Algae, with the oldest green algae dating from 850 Ma

Advantages & Disadvantages of Terrestrial Plant Life:


1) Light levels higher

2) CO2 more easily extracted


1) Not 100% humid air, so needed roots to get water up to photosynthesize tissue

2) Reproduction had to happen without water transport

2 Kinds of Terrestrial Plant Life (Embryophytes):

1) Bryophytes - simple plants, with conducting strands to move up water, and is necessary given waxy cuticles

2) Vascular Plants - advanced plants, with xylem (pipes for water flow), Phloem (pipes for sugar transport), intercellular gas transport tubes (O2 to roots, CO2 to leaves), lignin (material adding strength to xylem)

When did the earliest plant appear?

A type of bryophyte, the cryptospores appear in the Ordovician

Oldest vascular plant = Cooksonia

Types of Plants in Silurian & Devonian

1) Rhyniophytes (earliest vascular plant)

2) Trimerophytes

3) Lycopods & Progymnosperms

What are Progymnosperms?

Plants from the Middle Devonian to Carboniferous that contained secondary xylem in the form of wood

What is in Gilboa NY?

Early Paleophytic Forests, dominated by progymnosperms and lycopods

What are examples of Late Paleophytic Floras?

(Upper Paleozoic & Triassic)

1) Lycopods

2) Ferns

3) Horsetails

4) Seed Ferns = first gymnosperms

What were the Global Implications for Land Plant Evolution?

1) Binding of loose sediment by plant roots, changed erosion and sedimentation patterns

2) Created meandering rivers due to binding of roots

3) Created coal

4) Massive drawdown in CO2 led to the end of Early Paleozoic Greenhouse and beginning of Late Paleozoic Icehouse

5) Increase in permanent oxygen

6) Allowed for terrestrial animals

What were the early types of terrestrial animals?

1) Paleozoic Amphibians

2) Amniote Reptiles

- Had a cleidoic "closed" egg system

- Three types (Anapsid, Synapsid, Diapsid), based on fenestrae

What is in Joggins, Nova Scotia?

The earliest true reptiles, anapsids.

Evolution of Synapsids & Thermoregulation

1) Pelycosaurids had enhanced solar heating and could control temperature sail

2) Therapsids were partial endotherms

What was 'The Great Dying'?

The terminal Permian extinction, where 57% of families, and >95% of species went extinct

Especially lost Paleozoic Fauna

Led to decrease in floral biomass = measured by coal gap

What caused the Permian extinction?

1) Oceanic Anoxia, like the Serbian Traps, which is the sudden release of CO2

*Killed immobile marine filter feeders and terrestrial respirers with low CO2 tolerance

What were the 3 stages of the Triassic Recovery?

1) Lower Triassic Lag Phase = disaster biomass

2) Middle Triassic Rebound = same as pre-extinction (Lazarus taxa) or convergent with pre-extinction (Elvis taxa)

3) Upper Triassic Expansion = provided base biomass for Mesozoic Era

What were the main groups in the 'The Triassic Takekover'?

1) Amphibians

2) Marine Reptiles

3) Terrestrial Diapsid Reptiles (Lepidosauria, Archosaurs, Tehocodonts)

Why did the Archosaurs radiate?

They overcame the Carrier's Constraint, could be erect or semi-erect and were superior.

What is the Carrier's Constraint?

All amphibians, diapsids, and lizards had a sprawling posture, which meant they could not breathe and run at the same time.

Had to ambush prey.

What were the Thecodonts?

Steam group of Archosaurs that used all 3 postures.

1) Parasuchids = top carnivores of freshwater
2) Crocodiles = top terrestrial carnivores
3) Dinoaurs = With oldest dinosaur being the Eoraptor + Herrersaurus

What was 'The End-Triassic Extinction"?

An extinction due to massive volcanism, that eliminated most ornithosuchian diapsids synapsids and made room for dinosaurs.

How can we prove how fast dinosaurs moved?

1) Comparative Anatomy

2) Dinosaur Footprints

Comparative Anatomy

- First find weight, then compare with bone thickness

- Dinosaurs with high weight/foot area ratio would get stuck in mud, like Apatosaurus

Key Findings from Brontosaur Trackways

1) Herd Behaviour = parallel tracks and small in the middle

2) Roland Bird's Snorkelling Brontosaur theory is impossible, but not possible (would sink)

3) Brontosaurs had higher weight/foot size ratio in front than at back, so feet were impressed deeper in mud

*undertracks = not true tracks on surface

Key Dinosaur Speed Findings:

1) Relative Stride Length = stride length/leg length

2) Dimensionless Speed = Velocity squared/gravity*leg length

3) Most dinos had ambling speed around 2-5km/hr

4) Faster speeds shown at Winston in Queensland, Australia, with Carnosaurs racing at 11-20 km/hr

What are Homeotherms?

Animals that are able to maintain a constant body temperature, with most being endotherms or gigantotherms.

What are Heterotherms?

Animals that allow their body temperature to vary widely depending on external factors, and are ectothermic.

What are Ectotherms?

Animals that receive their body heat from an external source, and are favoured in warm climates.

What are Endotherms?

Animals that produce heat to regulate their internal temperature, and are favoured in cold climates.

What are Partial Endotherms?

Animals that can produce their own body heat, but are not able to fully overcome the effects of external temperature changes.

Inertial Homeotherms (Gigantotherms)

Large animals who maintain a constant high body temperature simply by virtue of their size.

4 Possible Solutions to Cold Blooded/Warm Blooded Debate:

1) All dinosaurs were ectotherms (overgrown lizards)

2) All dinosaurs were full endotherms (Bakker's Delight)

3) Dinosaurs were a diverse group that contained ectotherms, partial endotherms, and full endotherms

4) Large adult dinosaurs were gigantotherms, with juveniles and small adults being either endotherms or ectotherms.

Bob Bakker's Evidence and Arguments for all dinosaurs being endotherms:

1) Predatory-Prey Ratios - Dinosaurs ate more food, with 2-5% of dino community being carnivores (endothermic) like T-Rex. Concerns: 25% predator footprint ratios, gigantotherms could survive off 5 good feeds a year, and Bakker doesn't mention anything about prey

2) Upright Posture - all endotherms were upright

3) Running Speeds - no conclusive evidence though

4) Polar Dinosaus - Modern day reptiles confined to tropics, but dinos extended to poles (endotherms in cold, remember). However, the cretaceous was in a greenhouse, so it might not count

Later Evidence and Arguments in Cold Blooded/Warm Blooded Debate:

5) Plates & Frills - Stegosaurus had bony projection meant to releasing heat (gigantotherm)

6) Oxygen Isotopes - imply partial endothermy atleast

7) Bone Microstructure - some dinos have typical bone structure with osteons (vascular rings)

8) Nasal Turbinates - all endotherms have these in the nasal that increase O2 consumption, but not known to be present in any dinos

9) Feather - Endotherms have hair/fur, and some dinos had insulating fur = partly endothermic

What was Sinosauropteryx?

The feathered dinosaur.

What is is Liaoning Province, NE China?

A fossil Lagerstatten where numerous feathered dinosaurs are.

* Small theropods were endothermic.

What are Carnosaurs?

An informal group of large theropods united by their large size and formidable appearance.

Why was Pangea good for dinos?

1) Supercontinent of Pangea allowed for global distribution

2) Many species occur worldwide

How did the breakup of Pangea affect Carnosaur evolution?

1) Pangea nearly intact in the Middle Jurassic

2) Laurasia separated from Gondwana in Early Cretaceous

3) Gondwana breakup into continents by end of Cretaceous

*Gondwana had allosaurs, Laurasia had tyrannosaurids, species converged over time

How did Tyrannosaurs grow?

Slow in youth, rapid in teenage, maximum life span of 25 years

3 Concerns over T-Rex's ability to hunt?

1) Forearms too small.

2) Legbone Athletic Ability

3) Brain small and equivalent to modern lizard

Key Takeaways from T-Rex teeth?

1) Teeth were long and sabre-like, with square serrations

2) Inferior due to square serrations, like Komodo Dragon (had to ambush attacker and slash/poison)

Did T-Rex's have feathers?

They were ancestors of Sinosauropteryx, but probably the young had feathers to keep them warm but they fell off with age.

What was the plant life like in the Carboniferous and Permian?

Dominated by Paleophytic flora of ferns, seed ferns, and lycopods

What was the plant life like in the Triassic?

Dominated by Mesophytic flora of ferns, conifers, and cycads

Key Takeaways about Mesophytic Flora:

1) Food for most herbivore dinos
2) Dominated by gymnosperms (i.e. conifers)
3) Ginkgo - living fossil and important gymnosperm group

What was the plant life like in the Cretaceous?

Dominated by Cenophytic Flora, dominated by angiosperms (today's plants)

Angiosperms replaced gymnosperms when the low-browsing ornithisthians

Key Takeaways about Vector Pollination and Seed Dispersal

Angiosperms had flowers that used nectar,odour, colour & shape to attract insects to carry pollen - led to coevolution

What was the plant life like after the Permian?

Dominated by modern fauna, with gastropods, bivalves, corals, echinoids, bony fish, and marine reptiles

Mesozoic reefs built by rudists clams

2 Types of Mesozoic Cephalopods:

1) Ammonites - coiled, medium level carnivores, swimming invertebrates

2) Belemnites - cigar-shaped, common in marine ecosystems

Types of Mesozoic Marine Reptiles

1) Old Turtles

2) Large Crocodiles

3) Nothosaurs
4) Archosaurs

3 Types of Sauropterigians:

1) Icthyosaurs - small dolphin-like

2) Mososaurs - sea lizards

3) Plesiosaurs

2 New Mesozoic Aerial Groups:

1) Pterosaurs - group of flying diapsid reptiles

2) Birds

Evolution of Birds:

- Thomas Huxley proposed that birds evolved from dinos after his discovery of raptor Deinonychus.

- Evolved from early theropod dinos (3 toes, hollow bones), next step:

- Tenanurid dinos - 3 fingered hand, clavicles fused to form proto-wishbone (furcula)

- Maniraptorid - half-moon shaped wristbone

- Evidence that theropods had downy feathers, while some had plumose feathers (insulation and display)

What is Archaeopteryx?

The first bird, found by Solenhofen Limestone, which contains many similarities with reptiles

What is a 4-winged dinosaur?

Dinosaurs who had feathers on their back limbs.

What are Melanosomes?

The colour in dino/bird feathers.

The Radiation of Modern Birds:

- After the extinction of dinos in the Cretaceous, tertiary groups of modern birds rode

- Diatryma "terror bird" became dominant

What were the Cynodonts?

The most advanced therapsids, who are directly traceable into the the earliest mammals with innumerable intermediate forms

What were the mammalian characteristics that evolved?

1) Increasingly complex teeth and tooth replacement

2) Reduction in the number of bones in the lower jaw
3) Simultaneous increase in the number of bones in the inner ear

4) Fully upright stance

5) Full thermoregulation

6) Live Birth

7) Milk Production

What were the Morganucodontids?

An early stem group of mammaliformes, became marsupials and placentals

The most primitive mammals being the monotremes (protherians) which originated in Gondwana and were restricted there.

What were the Multituberculates?

The most common Mesozoic mammals, named after the rows of cuspate teeth.

2 Types of Therians?

1) Marsupials - pouch

2) Placentals - long gestation period, give birth to fully formed young

*originated in northern continents in Jurassic and Cretaceous

What forms were Mesozoic mammals?

1) Shrew-to-rat sized insectivores
2) Would have heightened senses with large brain

What was the Terminal Cretaceous Event?

A mass extinction event at the end of the Mesozoic (Cretaceous), 17% family extinction

Causes of Terminal Cretaceous Event

1) Volcanism - volcano, like Deccan Traps in India, erupted

2) Bolide Impact - meteorite/comet that produces dust to block out sun

What linked the extinction of the DInos to Bolide impact?

Walter Alvarez reported iridium anomoly when Cretaceous hit

Shocked quartz and chicxulub impact crater shown in Yucatan, Mexico

Followed by fern spike (disaster biota)

Factors that dictate mass extinction:

1) Size - no animal over 25 kg has ever survived mass extinction

2) Climate - tropical and reef biotas are vulnerable, polar not so much

3) Evolutionary Niche - more specialized, more in danger

Eocene-Oligocene Cooling resulted in:

1) More pronounced climatic belts with icy polar regions

2) Extensive extinctions amongst the archaic mammals (Le Grande Coupre)

3) Evolution of new mammalian groups to respond to changing climatic conditions and to fill the niches vacated by extinctions

What are Guilds?

Taxonomic groups that categorize ways of life that have evolved repeatedly among different animals

3 Mammalian Top Carnivores:

1) Mesonychids

2) Credonts

3) Carnivora

What are Megaherbivores

A guild of early elephants and mastadons plus extinct groups similar in size and life habit to modern rhinos & hippos

What are Grazers?

The size and diversity of the grazers were both similar to those of today, but in the Miocene consisted almost entirely of early horses (modern grazers are antelope and zebras).

What are Browsers?

Most ecological roles filed by similar but mostly unrelated species (camel vs. giraffe).

What are Mixed Feeders?

A similar array of different sized mixed feeder, but dominated by camels rather than antelope in the Miocene

What are Artiodactyls?

Even toed ungulates, like deer, sheep, camels, cows, pigs, and hippos

What are Perissodactyis?

Odd toed ungulates like horses, rhinos, tapirs

What are Titanotheres?

Animals that were common in Fossil Forests like Axel Heiberg Island

What are Chalicotheres?

Horse x Gorilla, with Indricotherium being largest land mammal ever.

What was Hyracotherium?

The most important Eocene Perrisodactyl, collie-sized animal

When was 'The Age of Horses'?


Two Fundamental Controls in the Evolution of Horses:

1) Migration - evolution most in NA, immigrated to Europe and Africa. Extinct in NA at end of Pleistocene.

2) Climate Change - Shift from C3 grasses to C4 grasses, favoured long tooth hypsodont grazers

What were Afrotheria?

Evolved in Africa and includes all modern elephants, sea-cows, hyraxes, and aardvarks

What were Xenartha?

Evolved in South America and includes all modern sloths, armadillos, and South American anteaters plus numerous taxa that went extinct in the Pleistocene

What was Holarctica?

The northern continent of Europe, Asia, and North America, where marsupials evolved

What is at Riverslieigh, NE Australia?

Superb record of mammal evolution, Oligocene to Present

What was 'The Great American Interchange'?

The gradual connection with North America and South America between the Pliocene with full land connected at end of Pliocene

What were the Plesiadapsids?

Squirrel sized creatures, known as the link between mammals and primates. Had opposable big toe and nails on two of its toes

2 Types of Primates:

From the Eocene of North America, Europe, and Asia

1) Adapsis = lemurs

2) omomyids = tarsier

What were Anthropoids?

Tarsier-like formed simians (ape + monkey) from Africa

*forward facing eyes, reduced snout, advanced ankles and thumbs

What was Aegyptopithecus?

The common ancestor of the apes and the Old World monkeys, and just after the split with the New World Monkeys

What is Prconsul?

The classic representative of the Homonoidea, from the late Oligocene-Early Miocene

What are Hominins?

All primates more similar to Homo than to chimpanzees

What is The East African Rift?

Plate Tectonic formation created rift, important for hominins coming from Africa

2 Early Hominins

1) Sahelantropus - Miocene

2) Ardipithecus - Miocene to Pliocene

- was faculative biped = sleep on ground or trees

What was Pamigrade Climbing

The early form of knuckle walking and tree swinging

Darwin's 2 Predictions about Man's Evolution

1) Humans evolved in Africa and that the oldest fossil humans would be found there

2) The evolution of large brain size was the impetus for the evolution of the features and attributes that characterize modern humans.

What were Australopithecines?

Previous to hominids, had ape like skull with human jaw (opposite to what Darwin thought). Was an obligate biped, shown by trackway at Laetoli

*Raymond Dart found example, Taung Child

2 Types of Australopithicines:

1) Gracile Australopithicines - mix of primitive & modern features i.e. Lucy

2) Robust Australopithicines - heavier with skull crest

2 Types of Homo:

1) Homo Habilis (2.3-1.6 Ma)
- "Oldowan" primitive tools

2) Homo Erectus (1.8-0.3 Ma)

- "Acheulean" hand axe tools

3) Neanderthals (150,000 -30,000 BP)

- More sophisticated tools than Erectus (Mousterian)

4) Early Homo Sapiens - used Aurignacian tools and carvings

What is Multiregional Theory?

Different populations of Homo Erectus of Africa, Europe, and Asia maintained some genetic interchange, but evolved into different races

What is Monogenisis Theory?

Homo Sapiens evolved in Africa 100,000-200,000 years ago. Proven right

*Homo Sapien migrations overlap with last of Pleistocene ice ages

What is the Blitzkreig (Overkill) Hypothesis?

The theory that humans were responsible for the mass extinctions of Wooly Mammoth, sabre-tooth tiger, 42 mammals, etc. due to the over-harvesting hunting tactics of humans.

What are Moa?

Ostrich-sized birds in New Zealand from 1000 years ago