K/T extinction event

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Effects[change | change source]

Dinosaur fossils are only found below the K–T boundary. This shows they became extinct before, or during the event.[3] Mosasaurs, plesiosaurs, pterosaurs and many species of plants and invertebrates also became extinct.


Causes[change | change source]

Scientists think the K–T extinctions were caused by one or more catastrophic events, such as massive asteroid or meteorite impacts (like the Chicxulub impact), and increased volcanic activity.

Several impact craters and massive volcanic activity, such as that in the Deccan Traps in India, have been dated to the approximate time of the extinction event. These geological events would have reduced sunlight and hindered photosynthesis, leading to a massive disruption in Earth's ecology.[4]

Craters[change | change source]


Related pages[change | change source]

References[change | change source]

  2. With "Tertiary" being discouraged as a formal time or rock unit by the International Commission on Stratigraphy, the K–T event is now called the Cretaceous–Palaeogene extinction event by many researchers. Gradstein F, Ogg J, Smith A. A geologic time scale 2004. http://www.cambridge.org/uk/catalogue/catalogue.asp?isbn=0521781426.
  3. Fastovsky D.E. Sheehan P.M. (2005). "The extinction of the dinosaurs in North America". GSA Today 15 (3): 4–10. doi:10.1130/1052-5173(2005)015<4:TEOTDI>2.0.CO;2 . http://www.gsajournals.org/perlserv/?request=get-document&doi=10.1130%2F1052-5173%282005%29015%3C4%3ATEOTDI%3E2.0.CO%3B2. Retrieved 2007-05-18.