G3 key idea 1

Question 1

mass extinctions

Answer 1

a mass extinction is when there is a massive decline in the number of different specie, over a relatively short period of time, perhaps spanning several thousand or even a few million years

Question 2

ordovician-silurian 443 Ma

Answer 2

Plankton and bottom dwellers, particularly brachiopods and trilobites
100 families extinct, including more than half of the brachiopod species

Question 3

albedo effect

Answer 3

the extent to which an object or medium reflects light

snow will reflect a high percentage of light energy, reducing the amount absorbed as heat energy

Question 4

permo-triassic 252 Ma

Answer 4

marine organisms
95% of all marine species
most brachiopods, corals, ammonites and trilobites
land reptiles, with 50% of all animal families and many trees die out

Question 5

major volcanic activity
Siberian Traps

Answer 5

areas in the vicinity of the eruption would be subjected to toxic gases, lava flows and pyroclastic flows, killing animals and plants nearby

ash sent high up into atmosphere, blocking sunlight, lowing global temperatures
causing global glaciations and a fall in sea level

following initial cooling, continued emission of greenhouse gases (CO2 and SO2) caused increasing global temp
acid rain would also have caused problems as gases react with water in the atmosphere

Question 6

supercontinent formation

Answer 6

Pangaea was formed when all the worlds continents collided together, forming one large land mass

meant fewer continental shelves so lack of habitat for shallow marine dwellers, accounting for the massive decline in shallow marine species

single continent would have caused rapid fluctuations in climate, and unstable weather patterns

as parts of Pangaea moved over northern and southern poles, there were widespread glaciations causing sea level regression, reducing shallow shelf environments

Question 7

methan hydrates

Answer 7

this is a solid form of methane
beloved to have formed within the sediments (thermal breakdown of organic matter), which remains solid and stable up to 18 degrees C

global increase in temp at the end of the permian is thought to have triggered these methane hydrates in the seabed to become mobile and gaseous, causing them to be released

Question 8

impact event

Answer 8

would have released gas and debris into the atmosphere

shocked quartz crystals found in Australia and Antarctica

shocked quartz - grains that have characteristics showing deformation under high pressure, linked with meteorite impacts

any impact craters found on the sea floor would have been destroyed (Wilson cycle)
weak evidence

Question 9

cretaceous-Tertiary 66Ma

Answer 9

bivalves, dinosaurs, ammonites, many families of fish, bivalves and many others

Question 10

evidence of asteroid impact
iridium layer, shocked quartz

Answer 10

layer of iridium concentrated in clays at the boundary, most iridium originates from space

shocked quartz layer

Question 11

tektites

Answer 11

spheres or irregular shaped lumps of solidified molten rock, a few cm in diameter
thought to have formed as a result of extremely high pressures and temperature (regional) caused by meteorite impact

found near impact craters

Question 12

tsunamis

Answer 12

large-scale sedimentary evidence in Texas that there was a huge tsunami at this time

Question 13

crater

Answer 13

large meteorite crater found in Mexico
shows a circular depression about 180km in diameter

Question 14

major volcanic activity
Deccan Traps

Answer 14

another enormous series of eruptions in India

Question 15

dinosaur adaptation
eating

Answer 15

ridged tooth - during chewing, rows of cheek teeth met at an angle to grind up food, typically vegetation

worn tooth - the chisel edge of the tooth, with its hard, outer enamel has been worn away by constantly chopping plants

Giant tooth - big mouth, massive skull, side, gaping jaws and large, sharp teeth are typical features of a larger predator

Question 16

hunting

Answer 16

pack hunters - some smaller carnivorous dinosaurs hunted in packs to attack prey larger than themselves
lightly built and agile, they had grasping hands and a large switchblade claw on each foot for slashing victims

long legs so they could run fast, excellent vision, and long, stiff tails that helped them to keep their balance

Question 17

protection

Answer 17

armoured skin and spiny defence, huge size and whiplash tail

some tended to heard together for protections, while dinosaurs that ran on their hind legs redid on speed or camouflage to escape