________________
Period
Bar width represents number of
living families
Groups experiencing
mass
extinction
Millions of years ago (mya)
540
490
Previous Extinction Events
Cambrian
445 415
360
Ordovician Silurian Devonian
Figure 19-8 Discover Biology 3/e ©2006 W. W. Norton & Company, Inc.
Ordovician: 50% of animal families, including many trilobites.
Carboniferous
Extinction Extinction
300
250 200
Permian Triassic Jurassic
Extinction Extinction
Devonian: 30% of animal families, including many fish and trilobites.
145
Cretaceous
65
1.8 0.0 Tertiary Quaternary
Extinction
Cretaceous: 50% of animal families, including the last of the dinosaurs and many marine species.
Triassic: 35% of animal families, including many reptiles.
Permian: 60% of animal families, including many marine species, insects, amphibians, and all remaining trilobites.
Chicxulub crater in the Gulf of Mexico - 65Ma Cretaceous
10
