1. Extinction Loss of a species or group of taxa
Primary cause: Failure of species to adapt to changes in environment
Extinction happens

2. Example: Species Lifespan
Mammals ~ 1 million year lifespan
5000 currently alive
Background rate ~ 1 species / 200 years
89 species extinct in last 400 years

3. Extinction
Mass extinctions account for
4% of all extinctions
The big 5 of the
phanerozoic.

4. Ordovician/Silurian Extinction
490 – 443 mya
Diversification of phyla, including 21 classes of echinoderms
Formation of coral reefs
Evolution of agnathans and trilobites
Plants invade land
Gondwana centered in southern hemisphere

5. Ordovician/Silurian Extinction
57% of marine genera wiped out
Probable cause: Global cooling
Glaciation over Gondwana led to cooling and drop in sea levels
Time span: 2 my (rapid)
Created opportunity for surviving species: ostracoderms

6. Permian/Triassic Extinction
Largest of mass extinctions
Lost 96% of marine species
Trilobites gone
Lost 75% of all land vertebrate families
Estimated that 84% of all genera on Earth became extinct
Time span: 1 million years
Prelude to the age of dinosaurs

7. Permian/Triassic Extinction
Plate Tectonics – Pangea formation
Supernova – destroyed ozone layer
Asteroid impact – trigger volcanoes
Siberian traps – 200,000 cubic kilometers
covered with lava
Global warming caused methane hydrate release from oceans
Oxygen depleted from oceans

8. Cretaceous/Tertiary Extinction
Extinction of Dinosaurs
50% of all genera
Pterosaurs, dinosaurs, sea reptiles
Cause: Asteroid impact
Prelude to the age of mammals

9. Iridium concentration
in clay layer at
KT Boundary
Other evidence:
Chicxulub crater
Microtektites
Soot deposits
Evidence of
tsunami

10. Evidence of the Impact Normal Quartz Shocked Quartz Abundant shocked
quartz and
microtektites
in the KT clay layer
in Caribbean

11. Microtektites from the crater
wall date to 65 mya

12. Direct Effects: Tsunami, dust induced global cooling,
fires, acid rain, earthquakes, volcanism
Indirect Effects: Disruption of ecological processes and
biogeochemical nutrient cycles.

13. Broadly distributed species are more
likely to survive extinction events
Bivalve Genera
Number of Geographical Provinces
Jablonski and Raup, 1995

14. Habitat Destruction Human Population by 2050 = 13 billion
Current extinctions are occurring at times
the normal or background rate.
May et al. 1995, Pimm et al., 1995
Human Population by 2050 = 13 billion

15. Vertebrates Hair Mammary Glands Amniotic Egg Endothermy Four Limbs
Cartilagenous
Fish
Hagfish,
Lampreys
Bony
Fish
Amphibians
Mammals
Birds
Reptiles
Hair
Mammary Glands
Amniotic Egg
Endothermy
Four Limbs
Terrestrial Phase
Bony Skeleton
Swim Bladder
Skull
Backbone
Paired Fins
Jaws

16. Mammals Hair, mammary glands Most advanced nervous system
Learning important to
survival
Warm blooded
Humans are mammals

17. Humans are primate mammals
Class Mammalia
Order Primates
Prosimians (e.g. lemurs)
Tarsiers
Anthropoids (e.g. monkeys, hominoids)

18. Lemur
Tarsier
Macaque

19. Primates : Humble Beginning
Rabbit
Shrew
Shrew-like
Ancestor

20. Homininae : African Great Apes
Major Primate Groups
Family Hominidae
Old World
Monkeys
Orangutan
Chimp
Human
Tarsiiformes
Gibbons
Gorilla
Lemurs
New World
Monkeys
Homininae : African Great Apes
and Humans
Hominidea : Great Apes and Humans
Hominoidea : Apes and Humans

21. What Features Are Associated With Primate Evolution?
I. Sensory Adaptations
Protected, forward looking eyes with stereoscopic vision
Improved sight : more detail even in low light
Reduction of olfactory structures

22. What Features Are Associated With Primate Evolution?
II. Adaptations for tree-climbing and insectivory
Freely moving limbs and digits
Long mobile digits capable of grasping
Retention of tail as organ of balance
Evolution of upright body posture and extensive head rotation
Increased body size
Evolution of nervous system to give precise and rapid control of movement