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OCR A LEVEL GEOLOGY > Evolution of life and climate > Flashcards

Evolution of life and climate Flashcards

1
Q

What is evolution?

A

Any change in the heritable traits within a population across generations.

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2
Q

What is a species?

A

A species is an organism that can interbreed to produce fertile offspring.

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3
Q

What is phyletic gradualism?

A

The theory holds that evolution is gradual and happens slowly over time. Is smooth and continuous. It involves the creation of new characteristics and genes due to cross-breeding and mutations.

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3
Q

What is punctuated equilibrium?

A

It suggests very little change occurs in the population, known as stasis. Large amounts of change will suddenly happen, the population will be forced to adapt, and a new species will take over in a short time. Usually due to environmental stress or change.

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4
Q

Why is the fossil record incomplete, and why cannot it be used to prove evolution?

A

Fossilization is rare so the record has lots of gaps
Soft tissues are usually missing so they don’t provide perfect evidence for evolution

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5
Q

What is genetic drift?

A

Where an “Island” population is isolated from the main populations, it may have varied genes and characteristics, and some can also be lost.

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6
Q

What is gene flow?

A

Movement of genes within a population or between populations.

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7
Q

What is convergent evolution?

A

Unrelated organism look similar because form follows function

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8
Q

What is meant by form following function?

A

Similar functions or ecological niches can lead to the evolution of similar physical traits or structures in different species. This principle can help explain convergent evolution, where unrelated species independently evolve similar traits due to similar selective pressures in their environments.

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9
Q

What can adaptation lead to in an evolutionary tree?

A

Leads to an increasingly complex, specialized, and diverse evolutionary tree.

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10
Q

Give three facts about the evolution of amphibians.

A

Evolved from lobe-finned fish
Late Devonian
Environmental pressure, such as seasonal rives and lakes, may have caused adaptation.

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11
Q

What is meant by “pentadactyl limbs”?

A

1 bone, which connects to two smaller bones, which connects to five or fewer smaller bones (Such as a hand)

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12
Q

What characteristics do lobe-finned fish and early amphibians share?

A
  1. Four limbs or fins (Tetrapod)
  2. Limbs in the same body position
  3. Pentadactyl limbs
  4. No keratin on limbs such as claws or nails
  5. Similar skull morphology
  6. Complex teeth
  7. Tail fin
  8. Scales
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13
Q

What adaptations did amphibians have to live on land in the Carboniferous Period?

A
  1. Skeletal girdle to transfer weight through bones
  2. A stronger skeleton to take weight due to gravity being stronger on land
  3. Eyelids to stop eyes from drying out
  4. Better blood circulation because moving on land requires more energy
  5. A tongue to sense surroundings
  6. Ears to hear as sound travels differently from air to water.
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14
Q

What traits and characteristics did the amphibians still keep when first living on land?

A

They still laid eggs in water or moist environments and fertilized them externally. Eggs lacked multicellular membranes or shells and were basically tadpole eggs.

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15
Q

What are the differences in characteristics between amphibians and archosaurs (birds, crocodiles, and dinosaurs)?

A
  1. Amphibians need water for reproduction, whereas archosaurs can reproduce on land
  2. Amphibian eggs have no shell, whereas archosaurs have amniotic eggs, which are hard and contain albumin, water, and nutrients.
  3. Amphibians have a larval stage after hatching, like tadpoles, whereas archosaurs have this stage inside the egg.
  4. Amphibians have moist skin, whereas archosaurs have dry skin
  5. Amphibians have a high predation threat, so they lay lots of eggs, whereas archosaurs lay less but care for their young.
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16
Q

What are archosaurs?

A

A group of reptiles such as dinosaurs, birds and crocodiles
A = BCD
Have diapsid skulls (two arches) and temporal fenestrae, which are openings in the skull that allow muscles to expand and lengthen.

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17
Q

What are the two groups of dinosaurs?

A

Ornithischians
Saurischians

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18
Q

What is the difference between Ornithischians and Saurischians?

A

Ornithischians
-Pubis points both up towards head and down towards tail
Saurischian
-Pubis points forward away from back bone
-Has a ball and socket joint at hip between the pubis and Ischium

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19
Q

What two groups can Saurischians be split into?

A

Therapods
Sauropods

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19
Q

Give a small summary of the evolution of the dinosaurs

A

Happened throughout the Mesozoic era (Triassic, Jurassic, Cretaceous)
252 MA mass extinction even at the end of the Permian (Lots of vacant niches)
Formed Pangea: Hot and dry
231 MA Eoraptor (First dinosaur)
Late Triassic divergence: Bipedal therapods (All carnivores)
Jurassic: The rate of plate tectonic rifting increased. Pangea splits into Laurasia and Gondwanaland.
The climate becomes wetter and milder, which increases the size of the dinosaurs
Cretaceous: Cooler, further continuous rifting (more isolation and more different evolution)
Late Cretaceous: Tyrannosaurus, horned dinosaurs, and duck-billed dinosaurs
Cretaceous/Tertiary mass extinction event

Dinosaur evolution is between two mass extinction events (Permian/Triassic and Cretaceous/Tertiary) (252 MA–60 MA)

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20
Q

What are the three dinosaur case studies for the adaptations to modes of life?

A

Tyrannosaurus, Saurischian, and Therapod

The largest terrestrial carnivore
Late Cretaceous
Large pointed serrated teeth (Suggests Carnivore)
Small eyes (suggest Scavenger)
Large olfactory lobes (suggest Scavenger)
Small arms (Suggests Scavenger)
Huge legs, slow (Suggests Scavenger)
Huge legs, walk far (Suggests Scavenger)

Diplodocus, Saurischian, Sauropod

Herbivore
Jurassic and Cretaceous
Long, slender skull (Suggests reaching for vegetation in forests and swamps)
Peg teeth, gut bacteria and gastroliths (suggesting plants were swallowed whole and then broken down internally)
Hollow bones (Suggests weight spread for efficient walking)
T-Shaped bones along spine suggest ligament attachment for better movement and control
Long whip-like tail (Suggests defensive weapon)

Iguanodon, Ornithischian, Ornithopoda

Herbivore
Late Jurrasic
Horny beak (Suggests herbivore for grabbing tough vegetation)
Leaf-shaped teeth and hinged cheeks suggest herbivore chew to get more nutrition from tough plants.
Grasping Hands (Suggests herbivore for pulling branches)
Quadrapedal (Efficient walking)
Bipedal (Suggests it is prey, can run fast, and suggests herbivores reach higher vegetation)
Tail (Balance)

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21
Q

What skeletal similarities do therapod dinosaurs and birds have in common?

A

-Hollow, thin-walled bones to make the bones less dense
-Shaped curved neck
-Elongated arms and forelimbs and clawed hands
The pubis shifted from an anterior (Forward position) to a posterior (Backwards position)
Large orbits (Eye sockets in the skull)
Hinged ankles (Reduces rotation)

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22
Q

What was the name for the first “bird-like” fossil?

A

Archaeopteryx

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23
Q

What similarities do therapod dinosaurs and reptiles have in common?

A

Long, bony lizard-like tail
Three digits on the wings with claws
Snout with developed reptilian teeth
Reptilian skull and brain
The sternum was not bony or keeled
Gastralia (belly ribs that do not circulate with ribs)
S-Shaped curved neck

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24
Q

Describe the evolution of feathers

A

The feathers that are found in the Late Jurassic are called proto-feathers and then evolved to become more complex, elongated, and symmetrical. There is some evidence of sexual dimorphism—a difference in size or appearance between the sexes of animals.

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25
Q

Describe trilobites.

A

Are arthropods
Grow by ecdysis
Common trace fossil
Huge adaptation radiation so they occupied many niches throughout the Palaeozoic
Have similar morphological features across species thought to be adaptations to similar environments:
Blind: low light or burrower
Small, easy to float
legs and feet—walked on sea bed

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26
Q

What is adaptation radiation?

A

Process in which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, alters biotic interactions, or opens new environmental niches.

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27
Q

What are the three types of coral?

A

Rugose - Bilateral symmetry of septa (TWO K’s one reversed)
Tabulate - No septa
Scleractinian - 6 Septa radial symmetry

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28
Q

How do brachiopods show adaptive radiation?

A

Adaptations linked to turbulent water, quiet water, soft substrate, and hard substrate was seen through different genera.

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29
Q

What were 4 adaptations linked to turbulent water found in different generas of brachiopods and give an example.

A
  1. A large predicle opening (foramen) - to support a large pedicle for secure attachment to substrate
  2. Strong ribbed valves - to strengthen shell against wave action
  3. A folded or zigzagged commissure- to reduce the amount of and size of sediment moving into the shells when the valves are open
  4. A thick and heavy shell - to provide extra stability on thr substrate and orevent rolling in thr current.

EXAMPLE: TEREBRATULA AND RHYNCHONRLLA (TURBULENT)

30
Q

What were 4 adaptations linked to quiet waters and soft substrate found in different generas of brachiopods and give an example.

A
  1. May have a median fold and sulcus - to separate currents of water entering and leaving animal. Prevents mixing or fresh water and waste
  2. Valves flat with a large resting area - to provide a large surface area to prevent sinking into the sediment
  3. May have extensions of the valves to form wings - to provide a large surface area to prevent sinking into the sediment (quiet waters are often muddy environments)
  4. Smooth or weakly ribbed valves - no need to be robust in quiet conditions
  5. No pedicle opening - pedicle not needed for attachment
  6. One margin of the shell may be turned upwards away from the sediment - to ensure that some part of the shell remains out of the sediment for feeding.

EXAMPLES: PRODUCTUS AND SPIRIFER

EXAMPLE:

31
Q

What were 4 adaptations linked to hard substrate found in different generas of brachiopods and give an example.

A
  1. Elongated ventral valve, cemented to the substrate at the base - for attachment in a high-energy environment
  2. May have spines from the ventral valve - to stabilise by extending these to the substrate, which prevents overturning by a current
  3. Small brachial valve - acts as a lid to open for feeding and respiration
32
Q

What is a mass extinction?

A

A massive decline in the number of different species over a relatively short period of time (1000-1,000,000 years)

33
Q

What are the four extinction events we need to know?

A

1.Pre-cambrian (GOE)
2. Ordivician - Silurian 443Ma
3. Permo-Triassic 252Ma
4. Cretaceous-Tertiary 66Ma

34
Q

Explain what happening the the Great Oxygenation Event during the pre-cambrian

A
  1. Early Earth had no oxygen in the atmosphere
  2. Early Earth had no dissolved oxygen in the oceans
  3. Very Early Life (bacteria), probably CHEMOAUTOTROPHS (producing energy by using chemical reactions from hydrothermal vents)
  4. Cyanobacteria evolved, and photosynthesised oxygen was produced as a waste product.
  5. The cyanobacteria formed layered mounds called STROMATOLITES
  6. The oxygen was toxic to most existing life. It was unlocked from rocks and other compounds.
  7. First, o2 was released into the sea water combined with dissolved iron (Fe2+), which produced solid iron oxide (rust) which sank forming layers called BANDED IRON FORMATIONS (BIFs)
  8. Oxygen production from cyanobacteria continued, even after all dissolved iron in the oceans had been precipitated
  9. This meant the remaining oxygen escaped into the atmosphere, permanently changing the composition
  10. This triggered global cooling leading to a SNOWBALL EARTH.
35
Q

Explain what happened during the Ordivician-Silurian mass extinction event.

A
  1. Gondwanaland is in the southern hemisphere, North Africa, at South Pole.
  2. A ice sheet formed, which caused a positive feedback loop due to the albedo effect
  3. Sea level fell as water is stored on land as ice, causing a loss of shallow shelf environments
  4. Further loss of shelf environments due to continental collision.
  5. High levels of lead, Arsenic and iron which could explain malformed plankton eg chitionozons and acritarch. Also affected trilobites, brachiopods and grapolites.
  6. Conodant elements (teeth) also show deformities and some extinctions.
  7. Extinct jawless fish teeth (like hagfish).
36
Q

Explain the theory of pangaea forming that explains the Permo-Triassic mass extinction.

A

Formation of pangaea
1. Loss of shallow shelf sea habitats (similar to Ordivician-Silurian)
2. Extreme continental climate (arid, no rain for centuries, extreme heat)
3. Led to fewer rivers due to being one land mass and a dry climate
4. Fewer nutrients (rock minerals) reach the coast causing weak food webs
5. Parts of pangaea were polar reducing sea level making continental shelves narrower.

37
Q

What is the second theory that would explain the Permo-Triassic mass extinction event?

A

Siberian Traps
- Major mantle plume (possibly triggered by an impact due to the evidence of shocked quartz grains of the same age found in Australia)
-Massive volcanic activity: flood basaltic of the Siberian LIPs (Large Igneous Province)
-Caused local deaths of life via lava flows, pyroclastic flows, Ash, toxic gases
-Caused global deaths of life via stratospheric Ash and gases which formed aerosols and block sunlight. This caused global cooling due to reduced photosynthesis and the albedo effect. Which led to less plants and killed herbivores, killing carnivores
-Greenhouse gases released from the volcanos, which caused warming after the cooling.
-sulphuric acid also created killing plant life.
-acidification of shallow water attacking CaCO3 shells

38
Q

What is the third theory that would explain the Permo-Triassic mass extinction event?

A

Methane Hydrates
-Solid crystalline lattice contains CH4, usually in marine sediments. This becomes unstable if water temperature rises, which causes methane gas to be released into the atmosphere, which is a greenhouse gas that caused global warming which released more methane.. positive feedback loop.

39
Q

What organisms were affected in the Permo-Triassic mass extinction event?

A

Marine organisms, 95% of all marine species, most Brachiopods, corals, ammonoids, trilobites.
Land reptiles, 50% of all animal families and trees die out
57% of all families
83% of all genera.

40
Q

What is the first theory for the Cretaceous - Tertiary mass extinction event?

A

Impact Event
-Bolide, probably an iron meteorite
180-km-diameter crater at Chicxulub, Yucatan, Mexico
-Iridium layer (Rare in crust, common in core)
-Shocked Quartz near impact crater
-Tektites (Frozen droplets of melted rock)
-Bolide impacted into shallow water (creating a mega tsunami) evidence in Texas - sedimentary structures
-Water was underlaying by limestone (CaCO3) and gypsum (CaSO4), leading to SO2 and CO2 gases released.
-Global cooling (Ash, SO2, Aerosols)
-Wildfires (Charcoal/soot layer all over the planet)
-Initial global cooling (Nuclear winter) followed by global warming and acid rain.

41
Q

What is the second theory for the Cretaceous-Tertiary mass extinction event?

A

Deccan traps
Indian LIP
Major mantle plume (possibly triggered by an impact due to the evidence of shocked quartz grains of the same age found in Australia)
-Massive volcanic activity: flood basaltic of the Siberian LIPs (Large Igneous Province)
-Caused local deaths of life via lava flows, pyroclastic flows, Ash, toxic gases
-Caused global deaths of life via stratospheric Ash and gases which formed aerosols and block sunlight. This caused global cooling due to reduced photosynthesis and the albedo effect. Which led to less plants and killed herbivores, killing carnivores
-Greenhouse gases released from the volcanos, which caused warming after the cooling.
-sulphuric acid also created killing plant life.
-acidification of shallow water attacking CaCO3 shells

42
Q

What is the third theory for the Cretaceous-Tertiary mass extinction event?

A

Methane Hydrates
-Solid crystalline lattice contains CH4, usually in marine sediments. This becomes unstable if water temperature rises, which causes methane gas to be released into the atmosphere, which is a greenhouse gas that caused global warming which released more methane.. positive feedback loop.

43
Q

What were the effects on life caused by the KT mass extinction event?

A

Bivalves and some fish families decreased, some survived. Belmnites, dinosaurs, ammonites, ptersoaurs, plesiosaurs, mosasaurs all extinct. 17% of families and 50% of all genera

44
Q

What is the anthropocene?

A

Morden epoch defined by human activities creating several permanent geological changes. Many scientists suggest using 1950 as its starting point (start of industrial revolution)

45
Q

What could be markers for the future of the anthropocene?

A

*chicken bones - chicken population increased for food
*ploughed soils with added nitrogen and phosphorus- will be seen in sedimentary rocks
*radionuclide eg Bikini Atoll 1946. Isotopes will be left in rocks after 1945 as well as from chernobyl 1986
*mass extinction accelerated by us
*microplastics
*soot layer - building up since industrial revolution

THESE ARE CALLED GSSPs (Global Standard Stratotype - section and points)

46
Q

What evidence is there for a snowball earth?

A

DROPSTONES - evidence for glaciation which are found on the equator (at the time the landmass would have been there) found by using palaoemagnetic evidence. If there was ice at the equator there would have been ice all around the globe

47
Q

Why did the snowball earth form?

A

*supercontinent on equator
*extremely high weathering rates
*carbonates formed in surrounding seas
*trapped cyanobacteria to form STROMATOLITES
*locked up carbon so less in atmosphere
*therefore temperature drops

Ice causes albedo effect:
Sea ice - 85% reflective
Open water < 10% reflective
Positive feed back loop
Once ice is over 30°N/S it is at a “tipping point”
647 MA
Single celled bacteria managed to survive (extremophiles). Enough light penetrator ice for some to survive
Often get energy from rocks
Snowball lasts for 25 MA

48
Q

Why did snowball Earth end?

A

Volcanoes were able to erupt through the ice, which released greenhouse gases such as CO2 which led to global warming and melting of ice
Within 3MA of thr melting multicellular life evolved.

49
Q

How did the snowball earth aggect life on earth?

A

*Before freeze oxygen levels below 1%, after freeze was 21%
*Large multicellular life was created

50
Q

How can milankovitch cycles cause climate change?

A

Eccentricity- 100 ka
Tilt - 41 ka
Procession- 20ka

51
Q

What are three ways of collecting evidence for past climate change (different to geography)

A

Measuring oxygen isotopes
Measuring carbon dioxide isotopes
Vail curves

52
Q

How are oxygen isotopes used as evidence for past climate change?

A

Oxygen has 3 stable isotopes:
O16 - most common (99.76%)
017 - rarest
018- (0.2%)

The oxygen isotopes found calcium carbonate shells at the time period wanting to measure. More O16 (less O18) in fossil shells = warmer climate as O16 is avalibe in the ocean.
Less O16 (more O18) in fossil shells = colder climate as O16 is trapped in snow/ice.
Often represented as delta (vhange in ratio of O18)

53
Q

How are vail curves used to measure past climates?

A

Vail was a petroleum geologist who wanted to see how sea level has changed overtime.

He found “First order cycles” which were at times of high sea level due to more MORs forming
“Second order cycles” were sea level changes with ice, volcanic activity, albedo effect, methane hydrates, and milankovitch cycles.

54
Q

What does eustatic mean

A

Global sea level change due to terrestrial ice forming or MOR formations.

55
Q

What does isostatic mean?

A

Isolated sea level change such as earth movement

56
Q

What evidence is there for sea level change?

A

Flooded landscapes - Doggerland, where tools and fossils have been found
Submergent landforms ei Flooded valleys such as ria and fjords
Emergent landforms such as raised beaches

57
Q

Summarise a small timeline of the main events that have happened in Earth’s history

A

4.567Ga - Earth forms
4Ga - life forms (single celled(
3.7Ga - Banded Iron Formations
3.5Ga - Photosynthesis
3.54Ga - Vaalbora Supercontinent forms
3.0Ga - Ur supercontinent forms
2.7Ga - Kenorland supercontinent forms
2.46-2.06Ga - Great Oxygenation Event
1.8Ga - Colombia super continent forms
1.6Ga - Multicellular life forms
1Ga - Rodinia forms + start of neoproterozoic
650-630Ma - Snowball Earth (no2)
541Ma - Cambrian Explosion
444Ma - Ordivician-Silurian mass extinction
330Ma - Pangaea forms
252Ma - Permo-Triassic mass extinction
252-66Ma - Dinosaurs
66Ma - Cretaceous-Tertiary Mass extinction event

58
Q

During the Silurian where was the UK located and what rocks formed?

A

25°S
Colonial coral reefs - 23-27°c - Reef limestone

59
Q

During the Devonian where was the UK located and what rocks were formed?

A

20°S
Old Red Sandstone - Southern desert belt

60
Q

Where was the UK located during the Carboniferous and what rocks were formed?

A

0°N
Reefs of colonial corals. Water temperature was 23-27°c. Coal formed from peat. Represents tropical rainforest growth

61
Q

Where was the UK located during the Permian, and what rocks were formed?

A

10° N
Waddie breccias, and dessication cracks. Zechstein sea. Evaporite deposits. Northern desert belt.

62
Q

Where was the UK in the Triassic, and what rocks were formed.

A

30°N
New red sandstone due to bedding red iron oxide cement. Very well sorted aeolian, millet seed sands

63
Q

Where was the UK during the Jurassic and what rocks were formed.

A

30° N
Reefs of colonial corals, water temperature 23-27°C. - limestone

64
Q

Where was the UK during the Cretaceous and what rocks were formed?

A

35°N
Chalk- is a fossil phytoplankton in a very productive shelf ecosystem

65
Q

Where was the UK during the Tertiary and what rocks were formed

A

40° N
Eocene orthoquartzite - is a silicrete duricrust. Mediterranean climate - palm trees

66
Q

Where was the UK during the Quaternary and what rocks were formed?

A

55°N
Till (boulder clay), outwash, varves, interglacial deposits

67
Q

What is lagerstäten?

A

Used to describe sedimentary deposits

68
Q

What are the two types of lagerstäten?

A

Konzentrat- lagerstäten concentration. Find many organisms in one bed, such as bones and organic hard parts.
Konservat- lagerstäten conservation. Are deposits known for exceptional preservation

69
Q

What are the ideal conditions for exceptional preservation?

A
  • Rapid burial in a protective sediment to protect from scavengers. (Entombment)
  • Burial in low energy environments
  • Anoxic or anaerobic conditions
  • Low PH as decay is slowed in high acidic conditions
    -Original material replaced early in diagenesis
70
Q

Describe the solohofen environment and how it helped with exceptional preservation

A

Southern Germany
140 MA - Jurassic
Solohfen Limestone
-Limited input of terrestrial sediment
- Shallow inland sea with reefs and lagoons, oxic surface layers, anoxic deeper
- Terrestrial and marine organisms
-Necrolytic features
- Rapid deposition of fine-grained carbonate .uds
- Evaporation crrstes topically, high salinity (hypersaline)
- No scavengers, no bacterial decay
- The “Lagoon of Death”
- Pterosaurs and archeyoptrx found

71
Q

Describe the Burgress shale environment and how it helped with exceptional preservation

A
  • Canadian Rockies
  • Middle Cambrian 508 Ma
  • Cambrian explosion
  • Benthonic, in situ, preservation sith some prior decay and disarticulation and some entombed (buried alive)
  • Tropical deep basin
  • Buried by turbity current slurry deposits
  • 40% arthropods with calcified exoskeleton
  • Limbs, antennae, gills, gut traces often preserved
  • Trace fossils present so sea floor was oxic
  • Animals such as hallucigenia, opabinia, anonalocaris.
72
Q

Describe the Ediacaran environment and how it helped with exceptional preservation

A
  • Ediacaren Hills AND Charnwood forest.
  • 550-545 Ma
  • PRE CAMBRIAN
  • Avalon explosion
  • Older than the first hard- shelled organisms
  • Oldest multicellular organisms
  • Soft bodied, sessile primitive organisms
  • Rapid evolution after snowball earth
  • Biota lived about 575Ma
  • Imprints of soft bodied in Sandstone
73
Q

Describe the Chengjiang environment and how it helped with exceptional preservation

A
  • 515 Ma
  • Start of the evolution of hard parts
  • Yunnan province, China
  • Soft tissues preserved as aluminiosilicate - oxidised
  • Species: Linguella, cardiodictyon, Circolosmia, Eldonia
  • Buried by turbidity currents
  • Influence of fresh water - changed seawater chemistry helping preservation
  • Benthonic preservation with little disarticulation
  • Show cyclic sedimentation
  • Cambrian explosion - High biodiversity
  • Shallow water

OCR A LEVEL GEOLOGY (12 decks)

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