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OCR Geology A Level > Chapter 11- Evolution and extinction > Flashcards

Chapter 11- Evolution and extinction Flashcards

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1
Q

cratons

A

stable portions of continental crust that are no longer tectonically active. Ancient, sometimes described as continental shields. mostly crystalline basement rocks. thicker parts of the crust

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2
Q

Great Oxygenation Event

A

biologically induced appearence of oxygen in the earth’s atmosphere around 2.3 billion years ago

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3
Q

snowball earth

A

condition in which the planet is either entirely frozen or is frozen to very low latitudes. Hypothesis is resisted by some as there is no clear mechanism to reverse the condition

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4
Q

albedo

A

fraction of solar energy reflected from the earth back into space. Ice and snow have high albedo

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5
Q

Kenorland

A

formed around 2.7 ga, first supercontinent. The breakup, 2.6 ga triggered a major climate change leading to the first snowball earth

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6
Q

Columbia

A

formed 2000-1800 ma and broke up 500 million years later. covered a third of the present land mass

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7
Q

Rodinia

A

1.0-0.6 ga, contained most of the earth’s continents. breakup triggered second snowball earth

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8
Q

pannotia

A

short lived supercontinent that formed at the end of the precambrian

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9
Q

pangaea

A

‘all the earth’ most recent supercontinent, 0.3-0.17 ga, formed of Gondwanaland and Laurasia

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10
Q

Gondwanaland

A

formed between 570 and 510 ma, included most of the southern land masses. included antarctica, s. america, africa, madagascar, australian continent, arabian peninsular, and india

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11
Q

laurasia

A

combines the names of Laurentia, (north american craton) and Eurasia. Contains most of the present N. hemisphere continents

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12
Q

variscan orogeny/ hercynian

A

mountain-building event caused by late palaeozoic continental collision between Euramerica and Gondwana to form pangaea

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13
Q

isostatic sea level change

A

due to uplift or subsidence of the continental crust, regional

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14
Q

eustatic sea level change

A

due to changes in the volume of ocean basins or volume of water in them. seen world wide

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15
Q

evolution of the atmosphere

A

-probably initially Hydrogen and Helium
-some water vapour, nitrogen, ammonia, methane, traces of oxygen
-water vapour condensed to form the oceans leaving co2 as the primary gas
-3.8 ga photosynthetic cyanobacteria began to produce oxygen which later leaked into the atmosphere

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16
Q

lithological evidence for climate change

A

-coal, pressence of peat indicates productive ecosystem
-desert sandstone
-evaporites
-tillites
-reef limestone

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17
Q

palaeontological evidence for climate change

A

-corals, fossil coral reefs must have needed the same conditions as modern reefs
-plants- tree rings and leaf size and shape are good climate indicators

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18
Q

isotopic evidence for climate change

A

-oxygen isotopes- atoms of oxygen within the ocean can vary. 18o in colder temperatures, 16o in warmer
-carbon isotopes- work in a similar way to oxyen but more reliable as they are more resistant to diagetic change

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19
Q

anthropocene

A

suggested name for the current global epoch. Refers to how human activity has been the dominant influence on climate and thee environment

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20
Q

holocene

A

the present epoch, relatively warm interglacial after the last major ice age

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21
Q

human impact on the environment/atmosphere

A

-2016, first time atmosphereic co2 stayed above 400ppm in the last 15million years
-rose from 280ppm since the industrial revolution
-fastest rate of increase since the cretaceous
-links the rise to rising temperatures and in turn links to rising sea levels as land ice melts
-human population has also doubled the amount of methane

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22
Q

human impact on the environment, biological changes

A

-likely responsible for causing the 6th major mass extinction event
-on course to lose 75% within a century

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23
Q

phyletic gradualism

A

model of evolution which states that most speciation is slow uniform and gradual

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24
Q

genes

A

sections of DNA that code for a protein. Made up of two alleles, one from each parents if the organism reproduces sexually

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25
adaptive radiation
a process when organisms diversify rapidly into many different forms, usually as a response to a change in the environment or to exploit a new ecological niche
26
punctuated equilibrium
periods of stasis where the population expands, followed by adaption as the population reaches the limit of its environment
27
genetic drift
-few pressures on the population -random sampling of genetic material eliminates some genes/characteristics -genes passed on and not better or healthier just lucky
28
gene flow
-exchange of genes between populations ie migration in animals or pollination in plants. can introduce genetic variation
29
morphology
describes the shape of an organism
30
benthonic
living on the bottom of the sea or a river, in or on top of the sediment
31
epifaunal
living on top of the sediment or substrate
32
substrate
sediment or rock at the bottom of the sea
33
pelagic
floating int he water column, usually the open ocean
34
nektonic
actively swimming in the water column
35
infaunal
living in the sediment, maybe as a burrower
36
adaptations of a trilobite
-exoskeleton: cephalon, thorax, pygidium. Comrpised of three layers, waxy outer layer and two further layers of chitin and protein. Middle layer impregnanted with calcium carbonate for added strength. Exoskeleton provides protection and support for attachment areas for muscles. Sensory hairs for detecting the environment -Complex compound eyes (if not blind) -each pleuron had jointed appendages for movement and gills for gaseous exchange -underwent ecdysis/moulting to grow -some could enroll into a ball for protection
37
benthonic trilobite
-calymene -large crescent shaped eyes, good depth, field of vision, and sensitivity to movement -many pleura, moved quickly, active metabolism, able to enroll
38
burrowing trilobite
-trinucleus -lack eyes, useless as depth -modified shovel shaped cephalon with spines- increase surface area to avoid sinking -sensory pits to detect the environment -dug shallow burrows for protection or to feed on the substrate
39
planktonic trilobites
-agnostus was interpreted as planktonic but was probably nekto-benthonic -some may have been planktonic as juveniles
40
pelagic trilobites
-opipeuter -lived high in the water column -large complex compound eyes so it could see above and below itself -separated pleura and an inflated glabella, which may have helped it stay bouyant -strong muscles, was a very good swimmer
41
nematoblasts
stinging cells to drive away predators or catch prey
42
polyp
soft-bodied part of the coral that sits inside the calice
43
corallite
cup-like calcareous skeleton of a single cotal polyp
44
bilateral symmetry
one plane of symmetry with two identical halves
45
mural pores
connections between adjacent corallites, perhaps for communication
46
radial symmetry
many planes of symmetry can be seen
47
corallum
whole skeleton of a coral, solitary or colonial
48
extant
species that still exists today
49
rugose coral
-extinct, ordivician to permian -colonial or solitary -bilateral symmetry -large corallites -always has tabulae and columella -6 major septa, 4 sets of minor septa -no mural pores -sometimes has dissepiments -lithostrotian
50
tabulate corals
-extinct, cambrian to permian -always colonial -radial symmetry -many small corallites -well developed tabulae but no columella -poor septa, when present -may have mural pores -reduced dissepiments when present -halysites
51
scleractinian
-extant, triassic to recent -colonial or solitary -radial symmetry -many small corallites -always has tabulae, sometimes has columella -major septa at 6 points -no mural pores -always has dissepiments -thecosmilia
52
symbiotic relationship
two organisms live together for mutual benefit. neither can successfully live without the other
53
zooxantellae
type of algae that lives symbiotically inside modern coral polyp
54
conditions necessary for corals to thrive
-at or just below sea level, few are found below 30m -clear waters, need sunlight -free from sediments that may clog the polyp, far from river sources etc -high energy levels/wave action, incorporates more water -fully marine environment, salinity of 30-40 ppt -temperature between 23 and 29 C
55
adaptations of brachiopods linked to turbulent waters
-large pedicle opened, supports a large pedicle for secure attachment -strongly ribbed valves, strengthens shell against wave action -folded/zigzagged commisure, reduce amount/size of sediment moving into the shells when valves are open -thick, heavy shell, for extra stability
56
adaptations of brachiopods linked to soft substrate/quiet waters
-median fold and sulcus to prevent mixing of fresh water and waste -flat valves with large resting area, prevent it from sinking into the sediment -extension of valves to form wings, larger surface area, as above -smooth/weakly ribbed valves, no need to be robust -no pedicle opening, unneeded for attachment -margin of the shell upturned to remain out of the sediment
57
adaptations of a brachipod linked to hard substrate
-elongated ventral valve, cemented to the substrate at the base -spines from the ventral valve to stabilise and prevent overturning -small brachial valve, acts as a lid, opens for feeding and gas exchange
58
similarities between brachiopods and bivalves
-two calcerous valves -umbos -growth lines -ribs -filter feeders
59
differences between brachipods and bivalves
-brachipods have two differently size, symmetrical shells. Bivalves have identical, asymmetrical shells -brachiopods have a pedicle, Bivalves have a foot -Bivalves have pallial line and sinus, brachiopods do not.
60
strophic
straight hinge line, sometimes extended as wings
61
astrophic
hinge line is not straight, may be shallow or highly curved
62
commisure
margain between valves at the posterior. may be curved, folded, or zigzagged
63
fold and sulcus
fold in the central part of the valves
64
spatfall
settling and attachment of juveniles to a substrate
65
amphibian
creature that is able to live in the water and on land
66
tetrapod
a creature with four limbs
67
lobe-finned fish
fish that possessed both lungs and gills, and had four fleshy fins, supported by bones in a similar structure to a hand -ie lungfish
68
terrestrial
describes anything relating to land
69
swim bladder
sac-like structure which can be filled with gas or fluid to control buoyancy in a fish
70
coelacanth
fish from an ancient lineage, closely related to lungfish and reptiles. Thought to be extinct since the end of the cretaceous but are actually extant
71
similarities between lobe finned fish and early amphibians
-skeletal similarities -limbs in the same position on the body -lacked claws/nails -skull morphology were similar -both had complex teeth -both had tail fins and bony scales on the skin
72
adaptations of amphibians to live on land
-girdle connecting limb bones to skeleton for better movement -more robust skeleton, ie strengthened vertebrae and rib bones -eyelids -double circularity system -tounge -ears
73
dinosaur
mesozoic reptile with upright walking position/gait
74
amniotic eggs
eggs with shells, performed by birds and reptiles
75
archosaurs
group of reptiles dominating the triassic. ancestors of dinosaurs, birds, and crocodiles
76
pubis
pubic bone
77
ornithischia
bird-hipped, two hip bones point backwards. one of the main divisions in dinosaur classifications
78
saurischia
other main dinosaur classification. 'reptile hipped', one of the hip bones points forward
79
gastroliths
stones swallowed by animals which stay in the stomach and grind the food they eat. would typically also have a gizzard, a lining of the stomach to protect it from damage
80
olfactory lobes
part of the brain that processes smell. larger = better sense of smell
81
characteristics of saurischian dinosaurs
-theropoda and sauropoda -alignment of hips similar to modern reptiles -long, s-shaped, flexible necks -hands consisting of three digits, the first being similar to a thumb -examples are velociraptor and diplodocus
82
characteristics of ornithischian dinosaurs
-hip arrangement similar to that of modern birds -front teeth are small or absent, replaced by a horny beak -many were armoured with bony plates, could have been defensive or acted as heat exchangers -iguanodon and stegosaurus
83
coelursaurus
type of therapod dinosaur, closely related to birds
84
dinobird
dinosaurs with feathers
85
furcula
wishbone- forked bone formed by fusing the collarbones, strengthens the skeleton ad allows birds to fly
86
sexual dimorphism
difference in size/appearance between sexes of the same animal
87
skeletal similarities between birds and theropoda
-hollow, thin-walled bones -s-shaped, curved neck -elongated arms/fore limbs and clawed hands -pubis shifted to anterior position -large orbits/eye sockets -hinged ankles
88

OCR Geology A Level (15 decks)

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