How are the mighty have fallen!
- II Samual 1:25
How did the joplly dinosaur
Improve each shining era?
By getting large and specialized
Extinction drawing nearer.
- Radcliffe "Blue Book"
Mass Extinctions
end of Ordovician
Devonian
Permian
Triassic
Cretaceous Periods
Permian extinction
85 percent of species including trilobites, most corals, bryozoans,crinoids, brachiopods
Triassic extinctions
end of conodonts
Cretaceous extinctions
end of dinosaurs, ammonites, marine reptiles, pterosaurs, many oyster species
Evidence at K/T boundary
iridiumalternative hypotheses
shocked quartz
tsunami deposits
meteorite impact (Luis Alvarez)
mantle plume (Loper, McCartney and others)
Useful links:
Earth Science Picture of the Day
Return to Historical Geology syllabus