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Mesozoic Life. Chapter 15 Part 3. Reptiles Dinos Marine Flying Today: mammals. Permian therapsids. Mammal-like reptiles in Permian More vertical legs Fur? Warm blooded?. Transition to mammals. Cynodonts Group of therapsid Late Permian/Triassic Not clearly either reptile or mammal.

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mesozoic life

Mesozoic Life

Chapter 15

Part 3

slide2
Reptiles
    • Dinos
    • Marine
    • Flying
  • Today: mammals
permian therapsids
Permian therapsids
  • Mammal-like reptiles in Permian
  • More vertical legs
  • Fur?
  • Warm blooded?
transition to mammals
Transition to mammals
  • Cynodonts
  • Group of therapsid
  • Late Permian/Triassic
  • Not clearly either reptile or mammal
mesozoic mammals
Mesozoic mammals
  • Late Triassic
  • Small during Mesozoic
  • Few species
mesozoic mammals6
Mesozoic mammals
  • Late Triassic
  • Small during Mesozoic
  • Few species
  • Mammal teeth
  • Reptile and mammal jaw joints
mesozoic mammals7
Mesozoic mammals
  • 2 branches
  • Prototheria
    • Monotremes: egg-laying mammals
mesozoic mammals8
Mesozoic mammals
  • Prototheria
    • Monotremes: egg-laying mammals
  • Platypus, echidna
mesozoic mammals9
Mesozoic mammals
  • Theria
    • Marsupial and placentals
where dinos warm blooded
Where dinos warm-blooded?
  • Modern mammals, birds: warm-blooded (endotherms)
  • Modern reptiles cold-blooded (ectotherms)
  • Maybe dinos were warm blooded
    • All were
    • Some were
    • Grew to be
how to establish
How to establish
  • Where they lived
    • Some dinos in polar climates
how to establsih
How to establsih?
  • Bones of modern animals
  • Endotherms
    • Bones with passageways with blood vessels
    • Ectotherms have fewer passageways
  • Dinos: bones more similar to modern endotherms
  • But some ectotherms have bones like endotherms
    • Not clear from this
how to establish13
How to establish?
  • Metabolic rate/food consumption
  • Enodotherms eat more with high metabolic rate
  • Endotherm predators need large prey population
  • Ectothermic predators may be 50% of population
  • Dino predators: 3-5% of population
how to establish14
How to establish
  • Brain size
  • Endotherm: Large brain relative to body to maintain temp
  • Some dinos had good sized heads
    • Small-medium theropods
  • Pin heads (sauropods) more likely ectothermic
how to establish15
How to establish
  • Heart construction
  • 4 chambers like living mammals/birds
  • Some reptiles with 4 chambers
how to establish16
How to establish
  • Feathered dinosaurs
    • Only endotherms have hair, fur, or feathers today
triassic extinction
Triassic extinction
  • 23% of marine and nonmarine families gone
causes of triassic extinction
Causes of Triassic extinction
  • Impact?
  • Manicougan impact crater, Canada
  • 214 Ma
causes of triassic extinction19
Causes of Triassic extinction
  • Volcanoes
  • SO2 and CO2 gasses
  • Massive environmental change
extinction of dinos
Extinction of dinos
  • Cretaceous-Tertiary boundary
  • K-T boundary
  • ~65 Ma
extinction of dinos21
Gone:

Dinos

Flying reptiles

Marine reptiles

Ammonites

Rudist bivalves

Some plankton

Cause:

Impact?

Volcanic eruptions in India?

Climate change, sea level drop?

All of the above?

Extinction of dinos
evidence of impact
Evidence of impact
  • Clay layer rich in element iridium
  • Iridium: rare on Earth
  • High concentrations in meteorites
  • 10 km diameter meteor impacted Earth
  • Where is the impact?
evidence of impact23
Evidence of impact
  • Yucatan Peninsula of Mexico
  • Town of Chicxulub
other theories
Other theories
  • Age of impact vs. age of extinction?
  • Volcanic source of iridium
    • Volcanic eruptions change climate
    • Massive eruptions in India at K-T boundary
other theories25
Other theories
  • Multiple meteorites:
    • Yucatan (65 Ma) 110 km wide
    • Ukraine (65 Ma) 15 km wide
    • North Sea (60-65 Ma) 19 km wide
    • Pack of comets struck Earth?
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