Life, 6th Edition

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The Fossil Record and the History of Life
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The Fossil Record Has Captured Many Important
Evolutionary Events
Examples

• Origin of amphibians/tetrapods
• Origin of birds
• Origin of mammals

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Lobe-finned fishes (rhipidistians)

• Appear in early Devonian (408 Mya)
• Had lungs and gills
• Lobed fins supported by bones
• Dermal bones w/ lateral line system
• Unique tooth structure

First Amphibians (Ichthyostega)

• Appear in late Devonian
• Have same unique skull structure,
• lateral lines, and tooth structure
• as rhipidistians
• Limbs and supporting bones larger
• Digits at ends of limbs

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Origin of Birds
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(No Transcript)
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http//www.dinosauria.com
http//www.senckenberg.de
Sinosauropteryx
No wings, but had feathers!
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http//www.student.tue.nl/t/p.kolbeek
http//www.toyen.uio.no/dinosaurer/images
Caudipteryx
Still flightless, but much larger feathers
http//rocek.gli.cas.cz/Rekonstrukce
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Microrapter
Four wings
Archaeopteryx
Big wings Opposable hind toe
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Confuciusornis
Modern bird (chicken)
Shortened tail with fused vertebrae
Breast keel Loss of teeth, finger claws
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Hollow long bones, 3-fingered hand, Elevated
first toe
Crescent-shaped wrist bone
Expanded breast bone
Small feathers
Larger feathers
Sickle-shaped claw on foot
Opposable hind toe
Short tail with fused vertebrae
Breast keel Loss of teeth and finger claws
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Origin of Mammals
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Skeletal Differences
Reptiles Mammals
Lower Jaw Jaw Joint Middle Ear Teeth Temp.
Fenestra

• many bones - dentary only
• articular quadrate - dentary squamosal
• stapes - malleus, incus, stapes
• uniform, single cusps - various, multicusped
• absent - large

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Carboniferous synapsid
Permian therapsid
Late Permian cynodont (therapsid)
Triassic cynodont
Late Triassic cynodont
Early Jurassic cynodont

• Loss of lower jaw bones
• Change in jaw joint composition
• Articular quadrate to middle ear
• Change in teeth
• Increase in temporal fenestra

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www.treknature.com
http//www.auburn.edu/academic/classes/zy/0301
http//www.condorcet.com.au
http//www.exn.ca/news
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A Brief History of Life
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Which dates and names to know?
Note error Carboniferous spans
Pennsylvanian and Mississippian only
Pregnant Camels Ordinarily Sit Down Carefully.
Perhaps Their Joints Creak. Possibly, Early
Oiling Might Prevent Poor Health.
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Table 20.1
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Precambrian
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Precambrian

• First prokaryotes 3.5 Bya
• First eukaryotes 1.5 Bya
• Multicellularity e.g. 640 Mya in
• animals

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Table 20.1
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Cambrian Period (543-510Mya)

• Rapid origin (10-15 My(?)) of modern phyla
• Origins may be much older (1 Bya)
• Body plan evolution spurred by Hox genes, etc.

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Table 20.1
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Paleozoic Ordovician to Devonian

• Origin of jawless fish (Ordovician)
• Jawed fish (Silurian)
• Ray-finned and lobe-finned fish
• (Devonian)
• Terrestriality in plants (Ordov.) and
• diversification (Devonian)
• Terrestriality in vertebrates and
• inverts (Devonian)

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Table 20.1
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Paleozoic Carboniferous and Permian

• Seed plants diversify
• First winged insects
• Insect orders diversify
• Lots of amphibians
• Origin of reptiles
• Permian finishes with mother of all extinctions
  (gt50 of families, gt90 of species). Esp. bad
  for marine organisms.

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Table 20.1
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Mesozoic

• Age of Reptiles
• Dinosaurs and others

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Mesozoic
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Mesozoic

• Mammals appear (late Triassic)

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Mesozoic

• Origin of teleost fish

http//bill.srnr.arizona.edu/classes/182
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Mesozoic

• Gymnosperms dominant in Triassic, Jurassic
• Angiosperms appear and flourish in Cretaceous
• Plant-associated insects also diversify during
  Cretaceous

http//www.ualr.edu/botany
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Mesozoic

• K/T extinction
• Evidence for impact
• All dinosaurs gone (but birds)

http//www.wm.edu/geology/virginia
http//www.bio.txstate.edu/upchurch
http//www.geo.vu.nl/smit
http//news.nationalgeographic.com
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Table 20.1
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Cenozoic Era had many epochs
Note error Carboniferous spans
Pennsylvanian and Mississippian only
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Cenozoic

• Mammals diversify
• Birds and snakes radiate
• Most modern families of plants and insects are
  formed
• Humans evolve

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Cenozoic

• Ice ages and interglacial periods in Pleistocene
• Glacial maximum was 18,000 yrs ago

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Cenozoic

• Extinction of Pleistocene megafauna

http//www.musei.unipd.it
http//www.evolutionnyc.com
http//www.royalalbertamuseum.ca
http//upload.wikimedia.org
http//www.researchcasting.ca