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 EraDevonian 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 EraPermian 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 EraPermian 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
Geologic Time Line
Triassic
Jurassic
Cretaceous
Tertiary
Quaternary
Mesozoic (245-66)
Cenozoic (66-0)
Period
Era:
37 64 78 64.8 1.6Duration
Mammalian Evolution
Overview of Geological Time Scale
2) Mesozoic EraTriassic 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 EraTriassic Period (~248-213 Mybp)
• 1st birds• gymnosperms dominate landscape• land masses connected = supercontinent = Pangaea, start
dividing late
Continental Drift – based on plate tectonicsi.e., continents floating on lithosphere via continually spreading ocean floor
Devonian Carboniferous Permian
Triassic Jurassic
Biogeography
Mammalian Evolution
Overview of Geological Time Scale
2) Mesozoic EraJurassic 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
Geologic Time Line
Triassic
Jurassic
Cretaceous
Tertiary
Quaternary
Mesozoic (245-66)
Cenozoic (66-0)
Period
Era:
37 64 78 64.8 1.6Duration
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
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
Cretaceous
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
Geologic Time Line
Triassic
Jurassic
Cretaceous
Tertiary
Quaternary
Mesozoic (245-66)
Cenozoic (66-0)
Period
Era:
37 64 78 64.8 1.6Duration
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 EvolutionOverview 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
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
Hyracotherium
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 grasslandsMerychippusMerychippus
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
Geologic Time Line
Triassic
Jurassic
Cretaceous
Tertiary
Quaternary
Mesozoic (245-66)
Cenozoic (66-0)
Period
Era:
37 64 78 64.8 1.6Duration
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
Pliocene & PleistocenePliocene & Pleistocene
TeleocerasTeleocerasTeleocerasTeleocerasPliohippusPliohippusPliohippusPliohippus
AgriotheriumAgriotheriumAgriotheriumAgriotheriumAmphicyonAmphicyonAmphicyonAmphicyon
AmbelodonAmbelodonAmbelodonAmbelodon
SynthetocerasSynthetocerasSynthetocerasSynthetoceras
EpigalusEpigalus
MegatheriumMegatherium
GlyptodonGlyptodon
CamelopsCamelops
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