3:57 PM Geological and climate changes and vertebrate evolution Flashcards
how old is the earth? what is geological time?
ime of the physical formation and development of the earth
The earth is 4.5 to 5 billion years old - life would have been there 4.5 to 5 bya- hot magma, internal mass heats up and fragmentation occurs, pangea splits/breaks
what are continental drifts?
○ Continental drifts - broken blocks moving on the hot magma (crust is the thinnest of the three and the coldest) - coalescence and fragmentation again (build break, build break, etc)
○
what are the units of time? - read when each one happened
○ Eons - the largest subdivision
§ Eras
□ Periods
® Epochs
life during pre cambrian vs mesozoic. when did chordates appear?
- Earth came with hot molten magma at the beginning - only minute archaea and bacteria) simple life existed - pre Cambrian
- Mesozoic - greater diversity of life
- Chordates happens during early cambrian
describe pre cambrian and cambrian periods
- Precambrian (4.5 bya) - first continental masses (Pangea starts breaks apart) creates lots of environmental change that will precipitate different life forms (archaea and bacteria at this point)
- Cambrian (542 Mya)- first vertebrates
describe devonian and late devonian
- Devonian (416 Mya) - anthropods and first fish diversity appear
- Late devonian - first tetrapods (cilicads) , four limbs start appearing
describe carboniferous, triassic, and jurassic periods
- Carboniferous (359 Mya) - radiation of reptiles
- Triassic (251 mya) - first mammals; dry interior continents, more terrestrial
- Jurassic (201.6 mya) - dinosaurs and birds radiate
define continental drift
• Continental drift - the movement of continental blocks on the mantle of the earth, can move towards or away from each other
define plates and plate techtonics. what do they result in? what is coalessence?
• Plates- masses of crusts that move independently of adjacent plates (dried as exposed when pangea separated)
• Plate tectonics - a process involving interactions of moving crustal plates
○ Results in major structural features of the earth
○ Concept essentially same as continental drift but focuses on the plates below the continents
process of fragmentation - coalescence - fragmentation
• As well, the positions of the continents in relation to the equator have also changed continuously
• Central spots may change
• Coalescence is coming together - plates collide
what does pangea break into? when?
• Some move further up, some move further down - those moving south will eventually be gondwana, and those moving north from the equator will be the laurasia. Pangea is before they separated
paleozoic - pangea
mesozoic - laurassia and gondwanna
cenozoic- all continents we have now - asia is eurassia
describe early paleozoic climate. during silurian? late devonian? mid carboniferous to mid permian?
• Early Paleozoic
○ O2 levels lower than current level of 21% (now 18%!!!)
○ CO2 higher - probable greenhouse effect
○ As oxygen rises - setting up a stage for life to develop
• O2 levels rose during Silurian - cyanobacteria photosynthesizing (???)
• Glaciation during late Devonian - periods of glaciation are associated with periods of cooling
○ Radiation of land plants - diversification, expansion
§ Sharp decrease in CO2 concentration
○ Much of gondwana covered with ice from mid-carboniferous to mid-Permian
○ Most vertebrates in the equatorial
what does continental drift impact?
Air temp, wind and air currents, precip. patterns, ocean currents, sea levels, formation of mountain ranges
how does continental drift impact air temps
- Small vs large land masses - the smaller the mass the easier it is to heat up, the larger it is the longer for temperature change to turn over
- Interior vs exterior land masses - interior is drier - greater rate of evaporation
- Less temperature fluctuation on interior (double check!!!)
how does continental drift impact wind and air currents
- Change with temperature over land and water
- Affect the life forms and change as temperature changes
- Changes in the size and position of land masses will affect the temp and wind pattern of airmasses
how does continental drift impact precip patterns
- Precipitation patterns
• Change with temperature and wind
Mountain building forms rain shadows - will eventually drop down as precip.
• Affected by wind pattern and evaporation rates
how does continental drift impact ocean currents
- Ocean currents and flow patterns change with movement and position of land masses
- Air temperature affected by warm and cold currents
- Ex. The arctic ocean is currently isolated from other ocean and does not receive warm water from the south because of the position and size of the land masses
how does continental drift impact sea levels
- Changes with sea floor spreading and melting of the polar ice caps and glaciers
- Late Mesozoic (245 mya) and early Cenozoic (65 mya) - many epicontinental seas (sea extending within the margins of a continent)
- Flooded large parts of continental interiors - especially north America and Eurasia
- More maritime climates will occur in continental interiors - during these times, a continental climate will prevail ( will become drier with less stable air temperature)
how does continental drift impact formation of mountain ranges
- Results when plates collide
- Affects air currents, precipitation patterns, animal and plant dispersal, and animal movement - serves as a barrier - one side may have more favorable conditions for life than the other
- Affects air temperature
- Will affect life forms
- Life forms will grow with more precipitation
how does continental drift impact geographic isolation
- Due to changing size, number, and position of the land masses and mountain formation
- Great effects on speciation and extinction - organisms may not be free to interact
- Zoography - the study of the diversity and distribution of animal taxa
- Zoogeography - life form, geographic distribution of animals
- Isolation - different species evolve, extinction, creation of new species because of the environmental condition
- Speciation will occur
how does continental drift impact bolide impacts
• Solar system - Oort cloud interactions with large asteroids, meteoroids, and comets have periodically modified the stability of ecosystems and ‘impacted’ the extinction of the majority of animal lineages.
•
