Week 8 to 11 Flashcards
(136 cards)
1
Q
What is the genetic evidence for early life in the Precambrian?
A
Genetic
-origin of life
-origin of cells
-origin of photosynthesis
-origin of eukaryotes
-origin of multicellularity
origin of sexual reproduction
-origin of animals
2
Q
What is the geological evidence for early life in the Precambrian?
A
-The Lewisian gneiss -> 3.0-1.8 bya
-Torridorian sandstone -> 1.0-0.77 bya
3
Q
What happened during the Urey-Miller experiment?
A
-Water, methane, ammonia and hydrogen gas react due to energy provided by electric shocks
-Amino acids produced which are the building blocks of life
-However they couldn’t replicate
4
Q
What’s the difference between eukaryotes and prokaryotes?
A
-Eukaryotes have membrane bound organelles with specialised functions but no cell wall
-Prokaryotes don’t have a true nucleus’s only a single strand of DNA
5
Q
What is the evidence for endosymbiosis?
A
-Mitochondria and chloroplasts are descended from formerly free living prokaryotes
-Molecular clocks estimate both events occurred in the Proterozoic
6
Q
What organism is present in Precambrian and modern day environments?
A
-Stromatolites
-Bacterial trace fossils found 3.5Ga
-Also forms in restricted environments eg Shark Bay, Australia
7
Q
What are some of the oldest fossils in the fossil record?
A
-Ifsaq gneiss in Greenland 3.8 Ga - isotopic evidence
-Apex Chert, Australia 3.4 Ga - contentious
-Strelley Pool, Australia 3.4 Ga - possible bacteria
-Gunflint Chert, Ontario 2 Ga - well preserved jasper used stromatolites
-Tappania 1.6 to 0.85 Ga - possible fungus
8
Q
How did the BIFs form?
A
-O2 reacts with Fe - insoluble
-3.5 to 2 Ga iron is used up
-After this atmospheric oxygen increases
-Iron is insoluble in oxygenated water
-Switch from pyrite conglomerates to red bands
9
Q
What are the pros of sexual reproduction?
A
-genetic variation
-the species can adapt to new environments due to variation
Less likely a population is affected by disease
10
Q
What are the cons of sexual reproduction?
A
-time and energy are needed to find a mate
-it is not possible for an isolated individual to reproduce
11
Q
What is the evidence for snowball earth?
A
-diamictite
-striated pavements
-dropstones
12
Q
What are the key events of the Ediacaran?
A
-origin of modern ecosystems
-related to the evolution of animal gut.
-Weng’an biota- animal embryos?
-Ediacaran macrobiota - animals?
13
Q
What was the Cambrian explosion?
A
- the major radiation of animals or fossilisable skeletons evolve independently in animal groups that diverged earlier
14
Q
What were the major events in the Cambrian?
A
-Trace fossils became much more diverse
-Explosion of small ‘shelly’ fauna
-Trilobites dominate
15
Q
What were the major events during the Early Ordovician?
A
-Iapetus ocean subducted
-Grampian orogenic event
-480-460 Ma
16
Q
What were the major events of the Middle Ordovician?
A
-Rheic ocean opens
-Iapetus ocean closes
-Continued island arc volcanism
-470-458 Ma
17
Q
What were the major events of the Late Ordovician?
A
-Avalonian and Baltica collide in the Shelvian event around 450 Ma
18
Q
What happened during the Silurian/Devonian?
A
-Laurentia + Baltica = Scandinavian event around 440 Ma
-Laurentia + Avalonia = Acadian event around 400 Ma
19
Q
What happened at the the end of the Ordovician?
A
-One of the ‘big five’ extinctions
-Short lived glaciation and sea level fall
-Killed 85% of marine species
-Limited impact on ecosystem structures
20
Q
What are the major events of the middle of the Palaeozoic?
A
-Radiation of vertebrates
-Terrestrialisation of plants, arthropods and vertebrates
-Decline of trilobites
- Late Devonian extinctions
21
Q
What are the challenges of life on land?
A
-support
- respiration
-water loss
-reproduction
-sensory systems
22
Q
What is terestrialisation?
A
-Organisms that have severed all ties with the sea, for breeding, feeding and distribution
23
Q
Why terestrialise?
A
-New food source and new habitats
-Escape from predators(at first)
-Reduced competition (at first)
24
Q
What evidence is there for terrestrial plant evolution?
A
-Molecular clock evidence from the Middle Cambrian- Lower Ordovician
-Fossil record shows dispersed spores and cuticle fragments from the Middle Ordovician of Gondwana
25
How have seeds evolved?
-Freed plants from reproductive necessity for water
-Permitted dryland colonisation
26
What are the origin of leaves?
-Cooksonia lacked leaves -> photosynthetic stems
-Eophyllophyton -> leaves small and rare
27
Why did leaves evolve?
Problem-> low CO2 levels and required greater surface area
Solution-> leaves
Problem -> water loss
Solution -> stomata
28
Why did plants grow taller?
Why? -> competition for light
How? -> wood
29
What adaptations did arthropods acquire to life on land?
-Structural -> avoid desiccation and increase uptake of fresh water: cuticle
-Respiration in air not water eg book gills
-Movement on land: exoskeleton
30
What are the 5 deuterostomes?
-Vertebrates
-Echinoderms
-Cephalochordates
-Hemichordates
-Tunicates
31
What are the ancient gnathosomes(jawed vertebrates)?
-Conodonts
-Placoderms
32
What are the key characteristics of ancient conodonts?
-Mineralised skeleton
-Dentine
-Enamel
33
What are the key characteristics of ancient placoderms?
-Pelvic fins
-Vertebrae
-Gill arches
-Jaws
34
When did Chondrichthyes evolve and what are they?
-Ordovician
-Cartilaginous fish
-Shark and rays
35
What are some of the adaptations tetrapods acquired when terrestrialising?
-Plates at the back of the skull
-More flexible necks for feeding and sensing
-Origins of shoulder and pelvic girdles to support body mass
-Larger eyes and are at the top of their head
36
What are some of the tetrapod, intermediate and fish like characteristics of tetrapods?
-Gills
-Scales
-Fins and fins with wrists
-Ears
-Limb like girdles
-Lungs
-Ribs
-Tail fin
-Skull
-Lateral line
37
What happened during the Early Carboniferous?
-Closure of the Rheic Ocean
38
What happened in the Late Carboniferous?
-The Tethys Ocean started to form
39
When was the Variscan orogeny and what were the key events?
-Devonian to Early Permian
-Formation of (Proto)Pangea
-E-W trend in UK
-Collisions of continents in the assembly of Pangea
-E-W oriented folds in southern England (due to N-S collision)
-Igneous intrusion and volcanic eg in Cornwall
40
What facies are from the Carboniferous in the UK?
-Mississippian limestones
-Mississippian/Pennsylvanian gritstones
-Pennsylvanian coal swamps
41
Why did the Carboniferous have such high O2 levels?
-Large equatorial forests so high photosynthesis
-Wood was buried in swamps without being decomposed
-Decomposition removes O2 from the atmosphere
-Burial without decomposition led to increased atmospheric O2 levels
42
What were the consequences of high O2 levels?
-Caused catastrophic fires
-Gave arise to giant arthropods
43
Why did O2 levels crash?
-Coal deposition stops
-Fewer low latitude swamps
-Organic matter decomposed removing oxygen from the atmosphere
44
What happened during the Early Permian?
-Dominated by uplift-> land almost everywhere
-Molasses troughs-> sandstones, shales and conglomerates that form as terrestrial or shallow marine deposits in front of mountain chains
-Playa lakes, flash floods and salt flats like environment
45
What rocks were mainly deposited during the Late Permian?
- Zechstein evaporites
46
What vertebrates were present in the Permian?
-Synapsids (Dimetrodon, Gorgonipsids)
-Diapsids (Youngina)
47
When was the P-T mass extinction and key features?
-252 Ma
-Sudden
-2 levels around 1Ma apart
48
How much of marine and terrestrial life went extinct after the P-T extinction?
-96% marine
-70% terrestrial
49
What caused the the P-T extinction?
-Volcanism(Siberian traps)
-CO2(anoxia, acid rain)
-Warming/greenhouse gases
-Tectonic configuration
50
What was the main role of marine plankton?
-Main groups of ocean plankton don’t evolve until the Mesozoic
-Early Jurassic planktonic foraminifera
51
What is a biological pump?
-Plankton drive a pump that moves carbon from the atmosphere to the sea floor
52
What happened during the Triassic recovery?
-Coral, coal and chert gaps
-Stepwise recovery from low to high tropic levels
-By the Middle Triassic, complex and stable ecosystems form
53
What were the 4 groups of vertebrate life in the Triassic?
-Diapsids
-Synapsids
-Curostarsans
-Archosaurs
54
What were the key events of the Mesozoic marine revolution?
-Predator-prey arms race
-More boring and shell-crushing predators
-More burrowing and thicker skeletons
-Brachiopods did badly
55
What were the top predators in modern oceans?
-mammals
-large fish
56
What were the top predators of Mesozoic seas?
-Sharks(Hybodus and Squalicorax)
-Large bony fishes(Leedsicthys and Ohmdenia)
-Marine reptiles (Pliosaurs, mosasaurs, plesiosaurs, ichthyosaurs and thallatosuchians)
57
What are the key characteristics of Icthyosaurs?
-Early Triassic
-First fish-like tetrapod
-Largest eyes of all vertebrates
-One of the earliest live birth records
-First marine tetrapod >20m
-First major fossil collected by M.Anning
58
What are the key organisms of Sauroplerygia?
-Middle Triassic to End Cretaceous
-Pliosaurs, Plesiosaurs, Nothosaurs, Placodonts
59
What are the key organisms of Mosasaurs?
-Late Cretaceous
-Tylosaurus, Prognathodon , Hainosaurus, Platecarpus
60
What are the key organisms of Thalattosuchia?
-Jurassic to Cretaceous
-Tyrannoneustes
-Steneosaurus
-Metriorhynchus
-Dakosaurus
-Geosaurus
-Plesiosuchus
61
What are the major challenges in an aquatic medium?
-Buoyancy
-Locomotion
-Respiration
-Obtaining water
Reproduction
-Sensory capabilities
62
What is convergent evolution and what organisms show a similar trend?
-The same body form evolved independently for a particular environmental specialisation
-Sharks and icthyosaurs show a similar trend
63
What are the two dinosaur phylum?
-Ornithschians-(Bird hipped)
-Saurischians-(lizard hipped)
64
What are the key features of Ornithischians?
-All herbivorous
-Stegosaursus
-Ankylosaurus
-Iguanodon
-Triceratops
65
What are the key features of Saurischians?
-Sauropodomorphs and Theropods
-Therapods-> Contains all known dinosaurian carnivores but not exclusively carnivorous eg therizinosaurs
-Also includes Archaepteryx and birds
-Sauropodomorphs-> Contains prosauropods and sauropods with Prosauropods initially facultative bipeds
-May have been herbivores/omnivorous
- Got longer and became quadrupeds
-Sauropods-> dominated in Jurassic, receded slightly in Cretaceous except South America eg Diplodocus, Apatosaurus, Dreadnoughtus and Amargasaurus
-Largest land animals ever
66
Why were they successful?
-Locomotion( digitigrade posture, straight knee joint etc)
-Endothermy
67
What are the different ways do organisms keep warm?
-Homotherm -> constant body temperature
-Poikilotherm -> variable body temperature
-Endotherm-> internal heat source
-Ectotherm -> external heat source
68
What are the advantages of endothermy?
-Constant energy supply/constant activity
-Active in colder climates
-‘immune’ to environmental fluctuations
69
What are the disadvantages of endothermy?
-Need constant fuel
-Overheat as increase in size
70
What defines a dinosaur?
-Perforated pelvis
-In-turned head of femur
-Straight knee joint
-Hinge-like ankle joint
-Digitigrade posture
71
What were the earliest dinosaurs?
-Middle Triassic origin(Carnian)
-Good record in South America
-Small bipedal animals
-Earliest herbivores and carnivores
-All three major clades represented
72
When did the dinosaurs radiate?
-Major radiation after Triassic-Jurassic
-Carnian diversification due to possible extinction
73
What caused the Late Triassic extinction?
-Sea level change?
-Asteroid impact?
-Central Atlantic Magmatic Province?
74
Was dinosaur radiation through competition or chance and what justifies either explanation?
-Morphological variation (disparity)
-Dinosaurs vs other archosaurs
-No sign of competition
75
What is the evidence for endothermy in dinosaurs?
-Polar dinosaurs
-Predator-prey ratios(estimation problems)
-Bone histology -> Haversian systems -> Metabolic rate or large size
-High growth rates
-Feathered dinosaurs
76
What phyla were thriving during the Cretaceous terrestrial revolution?
-Insects
-Birds
-Pterosaurs
-Mammals
-Herbivorous dinosaurs?
77
What are the 2 types of plants that were evolving during the Cretaceous?
-Gymnosperms(seed plants) eg ginkgo and cycads
-Angiosperms(flowering plants)
78
What other phyla evolved greatly during the Cretaceous?
-Insects(bees and wasps)
-Birds(archaeopteryx)
-Pterosaurs
-Dinosaurs
79
What are the 3 phyla of Dinosaurs that dominated the Cretaceous?
-Ornithischians
-Sauropods
-Therapods
80
Why is the fossil record of the Cretaceous incomplete especially for terrestrial fossils?
-Not much terrestrial facies in the rock record
81
What are some of the key characteristics of birds?
-Feather
-Toothless beak
-Hollow bones
-Perching feet
-Wishbones
-Deep breast bones
-Stump-like tailbones
-Enlarged brain
-Elongated hind limbs
-digitigrade posture
-asymmetrical flight feathers
-Elongated and fused fingers
82
What are the ‘Avian’ characteristics within Therapods dinosaurs?
-Hollow bones
-Calcified breastbone
-Feathers
-Grasping hand,long middle finger
-Elongated fingers
-Mobile wrists ‘wing folding’
83
What is some of the other evidence of birds deriving from Therapod dinosaurs?
-Brooding
-Nesting
-Sleeping positions
-Bird-like egg shell
84
What are the 6 feather types in modern birds?
-Filoplume
-Semiplume
-Contour
-Tail
-Down
-Wing
85
What happens to birds feathers as they grow?
-Feathers pass through different forms during development
-The different feather types have been seen in therapod dinosaurs
86
What dinosaurs showed feathers first?
-Sinosauropteryx
-Sinornithosaurus
-Microraptor
-Anchiornis
87
What are the challenges of flight?
-Heavy weight
-Generating lift
-Getting airborne
-Generating sufficient power
88
What are the adaptations to overcome the challenges of flight?
-Pneumatic skeleton in birds and pterosaurs
-Delicate skeletons in bats
-Feathers in birds
-Wing membrane in pterosaurs and bats
-Skeletal adaptations
-Taking off of cliffs and trees etc?
-Running?
-Keeled breastbone in birds
89
When did each phyla evolve flight?
-Insects (Palaeozoic)
-Pterosaurs (Triassic)
-Birds (Jurassic)
-Bats (Eocene)
90
Why is the origin of birds contentious?
-Modern clades originate pre or post KPg extinction?
-Conflict between fossils and molecules
-New evidence from a Cretaceous duck?
91
What happened during the KPg extinction?
-Dark clay layer with impact debris
-Spike in rare Earth element Iridium
-Negative carbon isotope excursion
-Sudden extinction of >95% plankton
-Rapid evolutionary radiation of new species of plankton
92
What caused the KPg extinction and what evidence supports this?
-Asteroid impact
-Stishovite: shocked quartz
-Microtektites
-Iridium spike
-Impact crater -> Yucutan peninsula
93
Why is Deccan volcanism the unlikely cause of the extinction?
-Main warming from Deccan volcanism happened 200,000 years before the boundary
-Extinction occur very rapidly at the KPg boundary
94
What were the effects of the bolide impact?
-Meteor hit evaporites and carbonates
-Sulphate aerosols, soot, CO2
-Acid rain
-Ocean acidification
-Darkness
-Impact winter
-Food-chain collapse
95
What evidence supports Tanis is the day the dinosaurs died?
-Deposit in N.Dakota that thought of to have formed on the day of the impact
-Fish, dinosaurs, turtles, pterosaurs
-Impact spherules in the gills of fishes
-Seasonal deposition of bone shows that they died in the N.Hemisphere spring
96
How did rainforests recover in the Paleogene?
-Mix of ferns, flowering plants and conifers with open canopies
-45% decline in plant diversity, recovery took around 6 million years
-Closed canopy, dominated by flowering plants and diversity continued to rise
97
How did mammals recover in the Paleogene?
-90% extinction of mammals
-Smaller after extinction
-Pre-extinction size within 100,000 years
-Rapid increase in size and diversity
-Linked to the evolution of the bean family?
98
What were the main synapsids through evolutionary time?
-Pelycosaurs -> dominant large animals(Carboniferous to mid Permian)
-Therapsids(non cynodont) -> dwindling in size and abundance with the rise of the archosaurs(Late Permian to mid Triassic)
-Cynodont therapsids -> only small critters during time of dinosaurs(Mid Triassic to end Cretaceous)
-Modern synapsids -> once again dominant large animals in fauna(Cenozoic to recent)
99
What were the origins of mammal characteristics?
-Insectivorous
-Fur and whiskers
-Milk teeth and fast juvenile growth suggests lactation and suckling
-Slow metabolism so probably not fully endothermic
-Reptile-like jaw
100
When did Morganucodon live?
-Late Triassic to Middle Jurassic
101
What were the major eras of the Cenozoic?
-Paleogene(66-23 million years ago)
-Neogene(23-2.6 million years ago)
-Quaternary(2.6 to present)
102
What happened during the Cenozoic?
-Continents move to the present positions
-Warm and humid -> cooling in Oligocene and Pliocene
-Increasing endemicity on land
-Dominance by birds and mammals
103
Where are the Cenozoic facies in the UK?
-South and South East UK
104
What was the Paleocene-Eocene thermal maximum?
-Sudden global warming event around 56 Ma
-Steady warming during Paleocene
-Then around 6 degrees C in 20,000 years
-Recorded in O(18) values in planktonic and benthic organisms
-Caused by CO2 and possible degassing of clathrates(methane ice cores)
-Extinction of benthic organisms
-Huge radiation of mammals ->dwarfing?
105
What evidence shows the PETM?
-Deep sea foraminifera from S.Atlantic show dwarfing and extinction
-Negative carbon isotope excursion -> injection of CO2 into the atmosphere
-Oxygen isotope shows warming
106
What was the North Atlantic Large Igneous Province?
-Rifting/opening of N.Atlantic leads to volcanism, intense activity
-Scotland and N.Ireland -> Giants Causeway, Skye and Mull volcanoes
-Possible trigger for the PETM?
107
What happened during the Alpine-Himalayan orogeny?
-Alps formed by collision of African and Eurasian plates (66-2.5 Ma)
-UK ca.100km from collision zone so only minor structures in S.England eg Lulworth Crumple and Weald anticline
108
What happened during the Middle Eocene?
-Spread of grasslands
-20-25% up to 40% of vegetation cover of savannah, wetlands and tundra
109
What were the 2 leaf physiognomies?
-Temperate -> small, toothed and deciduous
-Tropical -> large, entire, drip tip and evergreen
110
How did whales evolve?
-Closest relative is the hippo
-Both groups evolved from terrestrial ancestors
-First whales were terrestrial -> Pakicetus
-Later forms Ambulocetus were more aquatic and fossils are recorded from estuarine environments
-Dorudon had vestigial hind limbs, dorsoventral undulation and probably a tail fluke
111
When was titanoboa present?
-Paleocene (60-58 Ma)
-Implication on climate (average 30 degrees C in the tropics)?
-But giganothermy = 4-6 degrees cooler
112
What were the other Cenozoic fauna?
-Terror birds
-Earliest elephants
-Chalicotheres ( distant relatives of horses and rhinos)
-Indricotheres ( extinct hornless rhinos)
-Demostyglids (herbivorous aquatic mammals)
113
What happened during the Neogene?
-Antarctic glaciation continues
-Further cooling in the Middle Eocene
114
What happened to the fauna at this time?
-Whales and dolphins radiate
-Terrestrial mammals adapted to open terrain
115
What are C3 and C4 plants?
-Plants photosynthesise
-Use light and convert 6CO2 + 6H2O=C6H12O6 +6O2
-Fixes carbon
116
What are the 3 biochemical mechanisms?
-C3, C4 and CAM photosynthesis
117
What are C3 plants?
-Most plants C3 around 95% of plant biomass
-C3 arose first in the fossil record
-Thrives in moderate conditions (intensity, temperature, plentiful water supply, CO2 levels around 200ppm)
-Loose 97% of water
118
What are C4 plants?
-C4 plants fix carbon more effectively but require more ATP
-Lose less H2O during photosynthesis
-C4 are more effective than C3 in certain environments(drought, arid conditions with high temperatures with N or CO2 depletion)
119
How did C4 plants evolve?
-C4 arose independently up to 40 times during the Oligocene
-But diversified in the late Miocene
-Clear link to replacement to shady forests with higher temperature open grasslands
-61% of C4 plants are grasses
-3% of known plant species and 5% of plant biomass
- But 30% of all CO2 fixation
120
What are the extant C4 plants?
-Maize
-Millet
121
What is the Quaternary period?
-Famous for ice ages
-Glaciers extended to 40 degrees latitude
-Periodic filling of the English Channel
-Closing of the Bering Strait
-Extinction of large mammals at the end of the Pleistocene
-Human evolution
122
Where was the glacial maximum during the Pliocene ice age?
-Canada and N.USA
-N.Europe(Bristol)
-Pyrenees, Alps
-Siberian and Asiatic regions
123
What is the evidence for glaciation?
-Ice rafted debris
-Tillites(glacial moraine deposits)
-Striated pavements
-Flat bottomed valleys
-Depression of land and glacial rebound
-Land bridges eg Bering Strait
124
What evidence is there for climate change at this time?
-Pollen
-Oxygen isotopes
125
What are the key features of Sahelanthropus?
-6-7 Ma form Chad
-Ape-like and human like features
-Close to common ancestor of chimps and humans?
-Bipedal?
126
What are the key features of Ardipithecus?
-5.7-4.4 Ma from Ethiopia
-Fairly complete skeleton
-Likely a forest dwelling omnivore
-Adaptations to both climbing and bipedal walking
127
What are the key features of Australopithecus?
-4.2 to 1.9 Ma of South and East Africa eg Lucy
-Larger molars than chimps
-Mix of forest and savannah foods
-Walked upright but not for long distances
-Probably gave rise to both Panathropus and Homo
128
What are the key features of Panthropus?
-Robust ‘australopiths’
-2.6 to 1.3 Ma from S. and E. Africa
-Massive cheek teeth -> powerful chewing forces
-Probably chewed large amounts of low quality vegetation
-There is a debate about monophyly/polyphyly
129
What are the key features of Homo Erectus?
-Ca. 2.4 to 110,000 Ma
- First Homo species to have the modern body plan
-Upright
-Long legs
-Larger brains
130
What are the key facts of Homo neanderthalensis?
-430,000 to 40,000 bp
-Eurasia
-Robust bodies
131
What are the key facts on Homo sapiens?
-From 200,000 bp to present
-Spread from Africa
-Agriculture, technology, language and art
132
What is the genetic evidence of human evolution?
-Neanderthal genome well known from ancient DNA
-Denisovans are a human species known from only scrappy bones but well known genetically
-Evidence of interbreeding between modern humans, Denisovans and Neanderthals
133
What are the links to human evolution from climate change?
-Adaptation of homonins to drier environments
-Expansion out of Africa
-Modern civilisation during warm stable Holocene
134
Why is the Anthropocene being proposed?
-Origin of agriculture
-American colonisation
-Industrial revolution
-Great acceleration (mid 20th century)
135
Why has the climate changed over time?
-CO2 levels
-Albedo
-Position of continents
-Ocean circulation
136
Are we due a sixth big extinction?
-Very high extinction rates
-Comparison is difficult
-Rates similar to the ‘big five’
