Extinctions

1
Extinctions
Millions of Years
Intermediate
Major
Minor
Pliocene
0
Late Cretaceous
Late Eocene
Middle Cretaceous
Late Jurassic?
Late Triassic
Early Jurassic
200
Late Permian
Geologic Time
Late Devonian
400
Late Ordovician
Cambrian Events
600
2
Late Ordovician
20
Cretaceous- Tertiary
Permian- Triassic
15
Late Devonian
Late Triassic
Total Extinction Rate (families per million
years)
10
5
0
Paleozoic
Mesozoic
600
400
200
0
Geological Time (Ma)
From Raup and Sepkowski
3
Arbitrary Boundary
(a)
Proximity to Boundary
Lesser
Greater
Probability of Finding Fossils
Arbitrary Boundary
(b)
Signor - Lipps Effect
Proximity to Boundary
Few
Many
Number of Fossils
4
Hell Creek Formation
Lance Formation
Maastrichtian Dinosaur Localities in
Western North America
North Horn Formation
Kirtland Formation
Javelina Formation
5
Mosasaurs
Pleisiosaurs
Ammonoids
Marine Organisms That Became Extinct at End of
Cretaceous
6
Foraminifera Suffered Heavy Losses at End of
Cretaceous
7
100
88
Terrestrial Extinction at K/T Boundary Eastern
Montana
50
Species Extinction
10
Land- dwelling
Fresh- water
From Sheehan and Fastovsky, 1992
8
Sudden Extinction
Gradual Extinction
Tertiary
Cretaceous
Dinosaur Diversity
9
Artists Rendition of Impact
10
Chicxulub Impact Site
Chicxulub Impact Site
11
Bidart (France)
Caravaca (Spain)
Stevns Klint (Denmark)
Gubbio (Italy)
Sample Position (m)
Sample Position (cm)
Iridium Concentration (parts per trillion, by
weight)
Iridium Concentration (parts per billion, by
weight)
12
Map of 103 Known Iridium Anomalies Around the
World
13
Shocked Quartz
14
SEM Photo of Glass Spheres and Globules Molten
Droplets of Rock
15
.10
26 MA Periodicity
.06
.04
.02
0
100
200
0
Geological Time (106 yrs.)
16
Tertiary
Cretaceous
5
0
Sharks
7
Bony Fishes
14
6
8
Amphibians
1
1
Champosaurs
5
Crocodiles
3
11
0
Ornithischian Dinosaurs
9
0
Saurischian Dinosaurs
Lizards
3
Lizards
11
14
Turtles
19
Mammals
1
27
Number of Species
17
Pierre Seaway
Baculites compressus time approximately 73 MYA
Larson et al., 1997
18
Pierre Seaway
Baculites clinolobatus time approximately 69 MYA
Larson et al., 1997