Summary of Events
Fossil Record
Fossils
• Most found in marine sedimentary rock
• Three requirements:
1) need hard parts, e.g., shell, bone, teeth, wood
2) remains escape destruction after death
3) remains buried rapidly – stop decomposition –
minearlization process
Fossil Record
Fossils
• Preserved as:
– Original soft parts = buried and preserved in permafrost, ice,
saturated soils, amber…
– Original hard parts = shell, teeth, bones, wood = resist
weathering
– Altered hard parts = mineralization
Mammalian Evolution
Overview of Geological Time Scale
(Mybp = million years before present)
1) Paleozoic Era
Devonian Period (~408-360 Mybp)
- early in period = vascular plants invade land
- diversification of bony fishes
- 1st amphibians & insects (move onto land)
Mammalian Evolution
Overview of Geological Time Scale
1) Paleozoic Era
Carboniferous Period (~360-286
Mybp)
• large forests of vascular
plants
• 1st seed plants
• 1st reptiles (amniote egg)
• late in period = 1st internal
fertilization
Mammalian Evolution
Overview of Geological Time Scale
1) Paleozoic Era
Permian Period (~286-248 Mybp)
• appearance of subclass
Synapsida - synapsids
• Order Therapsida (therapsids)
= mammal-like reptiles
(mammalian grade of
anatomical structure)
• reptilian adaptive radiation
Order
Synapsid Reptiles
Pelycosaur
Therapsid
Mammalian Evolution
Overview of Geological Time Scale
1) Paleozoic Era
Permian Period (~286-248 Mybp)
• Mass extinction event –
largest?
• 90+% of marine species
extinct
• Causes? – glaciation,
reduction in ocean volume,
volcanoes
• Expansion of terrestrial fauna
• Pangea formation
Geologic Time Scale
Duration
Era:
37
78
64
Mesozoic
(245-66)
Quaternary
Tertiary
Cretaceous
Jurassic
Triassic
Period
Geologic Time Line
64.8 1.6
Cenozoic
(66-0)
Mammalian Evolution
Overview of Geological Time Scale
2) Mesozoic Era
Triassic Period (~248-213
Mybp)
“Dark Age of Mammals”
• therapsids declining in
numbers; nearly extinct by
end of period
• 1st dinosaurs
• 1st mammals = descendants of
remaining therapsids; small
body size (<120 mm)
Mammalian Evolution
Overview of Geological Time Scale
2) Mesozoic Era
Triassic Period (~248-213 Mybp)
• 1st birds
• gymnosperms dominate landscape
• land masses connected = supercontinent = Pangaea,
start dividing late
Continental Drift – based on plate tectonics
i.e., continents floating on lithosphere via continually
spreading ocean floor
Devonian
Carboniferous
Triassic
Permian
Jurassic
Biogeography
Mammalian Evolution
Overview of Geological Time Scale
2) Mesozoic Era
Jurassic Period (~213-144 Mybp)
• Pangaea divides into Laurasia & Gondwanaland (N-S)
• dinosaurs dominate land masses
Mammalian Evolution
Overview of Geological Time Scale
2) Mesozoic Era
Jurassic Period (~213-144
Mybp)
• archaic mammals; 1st
adaptive radiation in
mammals (pantotheres,
multituberculates,
symmetrodonts, triconodonts)
• adaptive radiation in birds
Geologic Time Scale
Duration
Era:
37
78
64
Mesozoic
(245-66)
Quaternary
Tertiary
Cretaceous
Jurassic
Triassic
Period
Geologic Time Line
64.8 1.6
Cenozoic
(66-0)
Mammalian Evolution
Overview of Geological Time Scale
2) Mesozoic Era
Cretaceous Period (~144-65
Mybp)
• dinosaurs extinct by end of
period
• Early- (~135 Mybp)
– N. America dominate by
marsupials,
multituberculates &
early placentals
– opossum-size mammals
Mammalian Evolution
Overview of Geological Time Scale
2) Mesozoic Era
Cretaceous Period (~144-65
Mybp)
• Early- (~135 Mybp)
– angiosperms flourish
(magnolias/tulip trees)
– insectivore/frugivore
dentition
– coevolution of flowering
plants & mammals (large
attractive flowers)
Mammalian Evolution
Overview of Geological Time Scale
2) Mesozoic Era
Cretaceous Period (~144-65
Mybp)
• Early- (~135 Mybp)
– trophic specializations &
foraging strategies
increasing in diversity
Mammalian Evolution
Overview of Geological Time Scale
Cretaceous
2) Mesozoic Era
Cretaceous Period (~144-65
Mybp)
• Mid- (~115-100 Mybp)
– western N. Amer. linked to
Asia
– eastern N. Amer. drifting
away from Europe
– Africa & India separate
from Gondwanaland
Mammalian Evolution
Overview of Geological Time Scale
2) Mesozoic Era
Cretaceous Period (~144-65
Mybp)
• Mid- (~115-100 Mybp)
– Condylarths (ungulate
ancestors) & marsupials in
"Euramerica"; also in the
connected S. Amer.
/Antarctica/Australia land
mass
– Stage set for major independent
radiations of mammals during
Paleocene
CHANGES IN DIVERSITY
Geologic Time Scale
Duration
Era:
37
78
64
Mesozoic
(245-66)
Quaternary
Tertiary
Cretaceous
Jurassic
Triassic
Period
Geologic Time Line
64.8 1.6
Cenozoic
(66-0)
Cretaceous
Tertiary
Mammalian Evolution
Overview of Geological Time Scale
3) Cenozoic Era
Tertiary Period (65-24 Mybp)
• Paleocene Epoch (~65-54
Mybp)
– major adaptive radiation
of marsupials &
placentals; also birds &
pollinating insects
– 1st primitive primates &
carnivores
Mammalian Evolution
Overview of Geological Time
Scale
3) Cenozoic Era
Tertiary Period (65-24
Mybp)
– Paleocene Epoch (~65-54
Mybp)
• marsupials move from
S. Amer. through
unglaciated Antarctica
to Australia
• marsupials restricted to
S. Amer. & Aust. refugia
when Antarctica is
glaciated
Mammalian Evolution
Hyracotherium
Overview of Geological Time Scale
3) Cenozoic Era
Tertiary Period (65-24 Mybp)
• Eocene Epoch (~54-38 Mybp)
– modern mammalian
orders appear
– further increase in
mammalian diversity
– angiosperm dominance
increases
Eohippus
Mammalian Evolution
Overview of Geological Time Scale
3) Cenozoic Era
Tertiary Period (65-24 Mybp)
• Oligocene Epoch (~38-24
Mybp)
– modern mammalian
families appear
– primitive horses, camels
Mesohippus
Mammalian Evolution
Overview of Geological Time Scale
3) Cenozoic Era
Tertiary Period (65-24 Mybp)
• Miocene Epoch (~24-5 Mybp)
– modern mammalian
subfamilies appear
– further mammalian &
angiosperm radiation
– whales, apes, grazing
mammals
– spread of grasslands
Merychippus
Overview of Geological Time Scale
3) Cenozoic Era
Tertiary Period (65-24 Mybp)
• Pliocene Epoch (~5-2 Mybp)
– modern mammalian genera appear
– apelike ancestors of humans appear
– land bridge between N. Amer. & S. Amer. forms
– large carnivores
Geologic Time Scale
Duration
Era:
37
78
64
Mesozoic
(245-66)
Quaternary
Tertiary
Cretaceous
Jurassic
Triassic
Period
Geologic Time Line
64.8 1.6
Cenozoic
(66-0)
Overview of Geological Time Scale
3) Cenozoic Era
Quaternary Period (~2 Mybp - present)
• Pleistocene Epoch (~2 - 0.01 Mybp)
– ice ages
– humans appear
– large mammal extinctions
Ambelodon
Pliocene & Pleistocene
Synthetoceras
Pliohippus
Teleoceras
Epigalus
Amphicyon
Agriotherium
Camelops
Megatherium
Glyptodon
Mammalian Evolution
Overview of Geological Time Scale
3) Cenozoic Era
Quaternary Period (~2 Mybp present)
• Recent Epoch (~0.01 Mybp present)
– historic time
– green & industrial
revolutions
– rapid loss of biodiversity
*Largest extinction event?
Fires in
South American
tropical forests
Biodiversity Hotspots
Biodiversity Hotspots
Biodiversity Hotspots
Biodiversity Hotspots
Biodiversity Hotspots
Biodiversity Hotspots
Biodiversity Hotspots
Biodiversity Hotspots