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Unit 3 Chapter 2

Biodiversity changes over time

QuestionAnswer
what is relative dating? dating artefacts to various periods in time based on where they are found in terms of the upper and lower strata of the rock.
what is numerical dating? dating artefacts through the process of radioactive decay to determine the age of the fossil.
how many mass extinctions have there been in earths history? 5 although some say that we are currently experiencing the 6th
what is a mass extinction? a period of time with a large loss of biodiversity
time period of Ordvican -Silurian? 445.6 - 439 mya
time period of Late Devonian? 416-359 mya
time period of Permian - Triassic? 299-251 mya
time period of Jurassic? 251-199 mya
time period of Cretaceous - Tertiary? 65 mya
what mass extinction had the greatest percentage of organisms lost? Permian - Triassic
what mass extinction was caused by global cooling, increased glacial areas and and a drop in sea levels? Ordovican - Silurian
what was the smallest mass extinction which lost 20% of organisms? Late devonian
What mass extinction is thought to be caused by human activity? the 6th mass extinction
Created by: lmjonh
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