Week 13: The End...KaBOOM Flashcards
background extinction
species are going extinct all the time
mass extinction
90+ species disappear over a very short intreval. Biggest mas extinction was end of Paleozoic.
K-PG extinction
creatous paleogene extinction
marks end of mesozoic :(
at least 50% of all species lost
on land almost nothing over 25kg survives
80-90% marine species lost
theory: meteorite
- Iridium found
- fern spores and pollen
- Soot
- tektites
- shocked quartz
- tsunami deposits
- crater
why enriched iridium to support comet theory
enriched iridium in clay layer between cretaceous rocks and tertiary rocks. Iridium found in comets and this iridium has been found in sites all across the globe
why fern spores and pollen to backup the comet theory
ferns colonize in impact sites and
can act as proxy for forest fires. just after K-PG massive spike in fern spores
why soot to back up comet theory
soot layers associated with the iridium layer . Evidence of massive global fires… possibly linked to the ferns spores
why tektites to back up comet theory
natural glass, produced by melting rocks during impact and that have been cooled quickly
why shocked quartz to back up comet theory
impact feature, cross hatched lines found in quartz (stress lines)
why tsunami deposits to back up comet theory
evidence of almost global tsnumai activity at end of cretaceous
Why the crater to back up comet theory
impact crater found in the gulf of mexico where tsunami deposits, shocked quartz and tektites are thicker towards this structure.
initial effects of comet
vaporizes all close by, forest fires, tsunami
long term effects of comet (after the impact)
- nuclear winter- ash covers sunlight for weeks to months, photosynthesis stops on land and oceans
- dust clears and water vapor remains in atmosphere creating greenhouse effect= super hot
- earth changes from drastically cold environment to a drastically hot environment
- base of food chains begin to die (if they haven’t already) ultimately killing those who eat them
- comet hit, causes earth quakes and volcanic eruptions- acid rain, ozone depletion and climate greenhouse effects
what actually killed the dinos? :(
there was already a steady decline in disparity in ceratopsians/hadrosaurids, theropods were steady but the comet was the final nail in the coffin
writing this chapter before bed makes me sad :(
avian dinos not affected like non avian dinos why?
avian theropods extinction was sudden most likely because they could eat the smaller animal that survived as well they would be the smaller ones who survived. Flying may have been a factor as why they survived.
