Lesson 11 (Rise of Mesozoic Biosphere) Flashcards
What is the greatest catastrophe in the biosphere
Permian - Triassic mass extinction
What started the perm-triassic mass extinction
Series of events, probably triggered by extensive volcanic activity in Siberia which led to global warming
what percentage of species on the planet became extinct during the permian triassic mass extinction?
96%
what was the supercontinent and super-ocean in the early triassic called?
Pangea
Panthalassa
What was early triassic climate like?
Harsh, hot, desert
What are evaporites
Natural salt/mineral left after the evaporation of a body of water
What rocks were found in the early triassic that suggested that the climate was hot?
Ventifacts and Calcretes
What were the poles like in in the early triassic?
No ice, probably more temperate so forests and diverse fauna could survive
Where can oxygen isotopes be taken from
Conodonts, the mouth part of the worm like chordate
What did the oxygen isotopes from the early triassic find?
Rapid warming to about 36 degrees celsius, peaked around 252.1 MA
Cooling after main extinction, second rise in temperature around 250.7 MA
What was the temperature like in the Late Smithian
Second rise, sea surface temperature rose to 38 degrees potentially exceeding 40 degrees
(sea temperature today at the equator rarely exceeds 30 degrees as reference)
what are the two stages in the early triassic recognized in the geographic time scale
Induan and Olenekian
- olenekian can be divided into smithian and spathian
what are ‘disaster taxa’
life forms that were left after the permo trassic boundary
what are some qualities of the disaster taxa
high abundance, low diversity
what is an example of a disaster taxa
Lystrosaurus
What are some qualities of the lystrosaurus
- Reptile
- Paired (dog like) tusks
- Belonged to group ‘therapsids’ or ‘mammal like reptiles’
- abundant during 251-247 MA, made up over 90% of terrestrial vertebrate species on Earth
- ‘shovel lizard’
Lystrosaurus eating and walking habits?
- no teeth, kind of a beak
- herbivore
- used tusks to grub up roots
- walk with legs wide out as opposed to tucked under body, similar to crocodile
- potentially able to burrow?
- ability to crop vegetation and burrow may be what allowed lystrosaurus to survive
What was the plant life like in the early triassic?
Forests were uncommon
plants would be dominated by smaller herbaceous forms like Pleuromeia and Dicroidium (seed ferns)
what is the coal gap
What was the ocean life like in the early triassic
- Similar to plant life
- dominated by high abundance, low diversity faunas of ‘disaster taxa’ (Lingula, Claraia)
- No corals (Coral gap for 10 million years)
- stromatolites were common
What was the biodiversity spread during the early triassic
- Inverse of life today, equator was a dead zone (gap in fossil record)
- life forms were not present at low latitudes
- applies to oceans as well
what life forms were found around the equator in the early triassic
- not many
- invertebrates (sessile mullusks)
- stromatolite reefs
what is the lilliput effect
a lot of taxa found during the early triassic were small in size
What was driving the impoverished Early Triassic and why did it last so long?
- high temperatures pushing organisms past thermal tolerance
- for most plants that is about 35 degrees celsius
- higher temperature requires more metabolism, more metabolism requires more oxygen
how long did the earth take to recovers after the permian - triassic extinction
5-7 million years (usually only takes a few hundred thousand years to recover)
what are some other problems that increased temperature created
- reducing oxygen conditions in the ocean (dysoxic or anoxic)
- rise in hydrogen sulfide
- Increased CO2
- caused more acidic oceans, causing problems for creatures with shells
How did the increase CO2 in the ocean cause problems for creatures
creatures that produce thick calcium carbonate shells or skeletons could only produce thin and weak shells
what maintained conditions during the early triassic that allowed them to last so long?
- potentially siberian traps releasing CO2
- this may have destabilized more methane hydrates, further warming the planet
- not currently proven
when did earths biota start to recover post permian?
middle - late triassic
when did the reef gap end
middle triassic
what do brachipods resemble
clams
how do brachiopods feed
using a lophophore, a ring of ciliate tentacles that they used to capture material suspended in the water column
what group dominated the sea shells of the mesozoic and cenozoic?
the mollusks (bivalves and gastropods)
what is a bivalve
clam
what is a gastropod
snail
which animal replaced the lystrosaurus in the middle triassic? What did they look like?
Archosaurus
What did Rauisuchia look like? What group are they a part of?
crocodile on long legs, Archosaurus
what did coelophysis look like
slender bipedal carnivore - probably agile runner, good depth perception
Traveled in packs
earliest mammal?
megazostrodon
date of luoping site?
Middle triassic
How many fossils in the Luoping site
20,000 fossils of fishes, reptiles, shellfish, shrimps and other seabed creatures
what is significant abou tthe Luoping fossil site
more more diverse ecosystem recovered than what is seen in the early triassic, close to pre-extinction levels
What does the Luoping fossil site suggest about recovery?
It took about 10 million years for a fully functioning ecosystem to develop
What surprising finding was true of many species found in the Triassic?
creatures looked a lot like other modern species, even if they werent related to them
What made some Triassic animals look like unrelated animals that lived much later?
evolution based on environment
What characteristics made Drepanosaurus look like birds?
Heads, eyes, beak, saddle shaped neck
Are the Drepanosaurus closely related to birds?
No, they are related to lizards
When does the rate of evolutionary change really take off? What is this phenomenon called?
Mass extinction leaves lots of niches open, allowing animals to transition/evolve to fill other roles
called adaptive radiation
What three examples are there of specific niches filled by reptile lineages?
- Rauisuchids - took on role of apex predator
- Aetosaurs - plant eating, covered in armour
- Phytosaurs - developed long snouts with bony teeth
What may have allowed the dinosaurs to survive the End-Triassic Mass Extinction?
Small and unspecialized
What is it called in evolution when similar selective pressures lead to similar physical results?
convergent evolution
