LIFE IN THE MESOZOIC

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LIFE IN THE MESOZOIC
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MESOZOIC LIFE

• Amphibians from the Devonian

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MESOZOIC LIFE

• Amphibians from the Devonian
• Reptiles from the Pennsylvanian

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MESOZOIC LIFE

• Amphibians from the Devonian
• Reptiles from the Pennsylvanian
• From the reptiles of the late Paleozoic arose two
  (three) divergent groups

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MESOZOIC LIFE

• Therapsids Reptiles
  Thecodonts
  
• (mammal-like reptiles) (ancestral
  archosaurs)
  
• Reptiles

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MESOZOIC LIFE

• Therapsids
• from stem reptiles

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MESOZOIC LIFE

• Therapsids
• from stem reptiles
• including ancestral pelycosaurs (Dimetrodon)

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MESOZOIC LIFE

• Therapsids
• from stem reptiles
• including ancestral pelycosaurs (Dimetrodon)
• more advanced skulls, teeth, hairy? endotherms?

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MESOZOIC LIFE

• Therapsids
• from stem reptiles
• including ancestral pelycosaurs (Dimetrodon)
• more advanced skulls, teeth
• Permian - Jurassic

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MESOZOIC LIFE

• Therapsids
• from stem reptiles
• including ancestral pelycosaurs (Dimetrodon)
• more advanced skulls, teeth
• Permian - Jurassic
• gave rise to mammals in Late Triassic

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MESOZOIC LIFE

• Therapsids
• Reptiles

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MESOZOIC LIFE

• Therapsids
• Reptiles
• skull characteristics
• (anapsids - no temporal opening - primitive
  reptiles and turtles)

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MESOZOIC LIFE

• Therapsids
• Reptiles
• skull characteristics
• (anapsids - no temporal opening - primitive
  reptiles and turtles)
  
• (synapsids - one temporal opening - pelycosaurs
  and therapsids, also euryapsids - ichthyosaurs
  and plesiosaurs -no descendants)

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MESOZOIC LIFE

• Therapsids
• Reptiles
• skull characteristics
• (anapsids - no temporal opening - primitive
  reptiles and turtles)
  
• (synapsids - and euryapsids one temporal
  opening)
  
• (diapsids - two temporal openings - lizards,
  snakes, alligators, dinosaurs)

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MESOZOIC LIFE

• Therapsids
• Reptiles
• Thecodonts

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MESOZOIC LIFE

• Therapsids
• Reptiles
• Thecodonts
• gave rise to
• alligators and crocodiles

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MESOZOIC LIFE

• Therapsids
• Reptiles
• Thecodonts
• gave rise to
• alligators and crocodiles
• phytosaurs -external appearance like crocodiles
  freshwater fish eaters

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MESOZOIC LIFE

• Therapsids
• Reptiles
• Thecodonts
• gave rise to
• alligators and crocodiles
• phytosaurs -external appearance like crocodiles
  freshwater fish eaters
  
• pterosaurs - flying reptiles

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MESOZOIC LIFE

• Therapsids
• Reptiles
• Thecodonts
• gave rise to
• alligators and crocodiles
• phytosaurs -external appearance like crocodiles
  freshwater fish eaters
  
• pterosaurs - flying reptiles
• dinosaurs

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MESOZOIC LIFE

• dinosaurs pterosaurs phytosaurs
  crocodiles
  
• thecodonts
• reptiles

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MESOZOIC LIFE

• Dinosaurs
• two (or three) orders which arose from thecodonts

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MESOZOIC LIFE

• Dinosaurs
• two (or three) orders which arose from
  thecodonts
  
• first fossils from Triassic (230mya) of Argentina
  (Sereno and Bonaparte, 1989)
  
• early thinking about dinosaurs - big, dumb and
  slow swamp living creatures

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MESOZOIC LIFE

• Dinosaurs
• two (or three) orders which arose from
  thecodonts
  
• first fossils from Triassic (230mya) of Argentina
  (Sereno and Bonaparte, 1989)
  
• early thinking about dinosaurs - big, dumb and
  slow swamp living creatures
  
• dinosaur heresies - Bakker

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MESOZOIC LIFE

• Bakker
• ectotherms or endotherms?

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MESOZOIC LIFE

• Bakker
• ectotherms or endotherms?
• most land animals of 20 lbs or more are endotherms

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MESOZOIC LIFE

• Bakker
• ectotherms or endotherms?
• most land animals of 20 lbs or more are
  endotherms
  
• energy budget of endotherms is 10-20x that of
  ectotherms

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MESOZOIC LIFE

• ectotherms or endotherms?
• most land animals of 20 lbs or more are
  endotherms
  
• energy budget of endotherms is 10-20x that of
  ectotherms
  
• if dinosaurs were dumb and slow, why were they
  the dominant life form for 150my? (No
  non-dinosaur larger than a turkey walked the land
  during the age of dinosaurs)

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MESOZOIC LIFE

• energy budget of endotherms is 10-20x that of
  ectotherms
  
• if dinosaurs were dumb and slow, why were they
  the dominant life form for 150my?
  
• mammals appeared about the same time as the
  dinosaurs (Triassic), but not important until
  about 65mya

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MESOZOIC LIFE

• energy budget of endotherms is 10-20x that of
  ectotherms
  
• if dinosaurs were dumb and slow, why were they
  the dominant life form for 150my?
  
• mammals appeared about the same time as the
  dinosaurs (Triassic), but not important until
  about 65mya
  
• metabolism? cant measure directly

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MESOZOIC LIFE

• if dinosaurs were dumb and slow, why were they
  the dominant life form for 150my?
  
• mammals appeared about the same time as the
  dinosaurs (Triassic), but not important until
  about 65mya
  
• metabolism? cant measure directly
• bone histology-blood vessels and haversian canals
  (calcium-phosphate exchange)

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MESOZOIC LIFE

• metabolism? cant measure directly
• bone histology-blood vessels and haversian canals
  (calcium-phosphate exchange)
  
• cruising speed - limb length and stride length
  Bakker concluded that dinosaur cruising speed was
  like that of large endotherms today

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MESOZOIC LIFE

• metabolism? cant measure directly
• bone histology-blood vessels and haversian canals
  (calcium-phosphate exchange)
  
• cruising speed - limb length and stride length
  Bakker concluded that dinosaur cruising speed was
  like that of large endotherms today
  
• latitudinal zonation - dinosaurs in many
  latitudes including areas with long nights -
  Alaska

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MESOZOIC LIFE

• metabolism? cant measure directly
• bone histology-blood vessels and haversian canals
  (calcium-phosphate exchange)
  
• cruising speed - limb length and stride length
  Bakker concluded that dinosaur cruising speed was
  like that of large endotherms today
  
• latitudinal zonation - dinosaurs in many
  latitudes including areas with long nights -
  Alaska
  
• predator to prey ratio -

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MESOZOIC LIFE

• predator to prey ratio
• Dimetrodon about 0.35 to 0.6
• modern lizard about 0.3 to 0.6
• modern mammal predators
• lion 0.025
• weasel 0.03
• Bakkers calculation for dinosaurs 0.01 to 0.03

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MESOZOIC LIFE

• metabolism (continued)
• oxygen isotope ratios in dinosaurs like those of
  modern mammals

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MESOZOIC LIFE

• metabolism (continued)
• oxygen isotope ratios in dinosaurs like those of
  modern mammals
  
• nasal passages (Ruben et al., 1996) dinosaurs had
  ectothermic type nasal passages

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MESOZOIC LIFE

• metabolism (continued)
• oxygen isotope ratios in dinosaurs like those of
  modern mammals
  
• nasal passages (Ruben et al., 1996) dinosaurs had
  ectothermic type nasal passages
  
• gigantism - body retains heat well

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MESOZOIC LIFE

• metabolism (continued)
• nasal passages (Ruben et al., 1996) dinosaurs had
  ectothermic type nasal passages
  
• gigantism - body retains heat well
• rapid growth of young - endothermic? (Horner)
  reported growth of 9 ft per year

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MESOZOIC LIFE

• metabolism (continued)
• nasal passages (Ruben et al., 1996) dinosaurs had
  ectothermic type nasal passages
  
• gigantism - body retains heat well
• rapid growth of young - endothermic? (Horner)
  reported growth of 9 ft per year
  
• Ruben et al. (Science, 1997) - theropod lungs
  were not capable of supporting endothermy

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MESOZOIC LIFE

• SAURISCHIA
• Sauropods Theropods
• herbivores carnivores
• quadrupeds bipedal
• Thecodonts

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MESOZOIC LIFE

• ORNITHISCHIA
• Ornithopods Ceratopsians Ankylosaurs Stegosaurs
• Thecodonts

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MESOZOIC LIFE

• Largest land animals - sauropods

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MESOZOIC LIFE

• Largest land animals - sauropods
• (Supersaurus - 134 ft long, 100 tons, Curtice,
  1996)
  
• (Ultrasaurus - probably not a valid group)

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MESOZOIC LIFE

• Largest land animals - sauropods
• (Supersaurus - 134 ft long, 100 tons, Curtice,
  1996)
  
• (Ultrasaurus - probably not a valid group)
• Marine animals
• Blue Whale - 106 feet, 140 tons

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MESOZOIC LIFE

• Life in the air
• for 200 my insects ruled the air

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MESOZOIC LIFE

• Life in the air
• for 200 my insects ruled the air
• Pterosaurs
• from thecodonts in the Jurassic to end of
  Cretaceous

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MESOZOIC LIFE

• Life in the air
• for 200 my insects ruled the air
• Pterosaurs
• from thecodonts in the Jurassic to end of
  Cretaceous
  
• (Quetzalcoatlus - up to 45 foot wingspan)
• mostly over shallow seas, - fish and squid diet

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MESOZOIC LIFE

• Life in the air
• for 200 my insects ruled the air
• Pterosaurs
• from thecodonts in the Jurassic to end of
  Cretaceous
  
• (Quetzalcoatlus - up to 45 foot wingspan)
• mostly over shallow seas, - fish and squid diet
• Birds

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MESOZOIC LIFE

• Birds
• from Jurassic

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MESOZOIC LIFE

• Birds
• from Jurassic
• feathers
• (some theropods may have had feathers for
  insulation - China, 1996 (120mya))

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MESOZOIC LIFE

• Birds
• from Jurassic
• feathers
• (some theropods may have had feathers for
  insulation - China, 1996 (120mya))
  
• Archaeopteryx

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MESOZOIC LIFE

• Birds
• from Jurassic
• feathers
• (some theropods may have had feathers for
  insulation - China, 1996 (120mya))
  
• Archaeopteryx
• furcula present - most other features like small
  carnivorous dinosaurs

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MESOZOIC LIFE

• Birds
• from Jurassic
• feathers
• (some theropods may have had feathers for
  insulation - China, 1996 (120mya))
  
• Archaeopteryx
• furcula present - most other features like small
  carnivorous dinosaurs
  
• sternum not keeled, finger and wrist bones not
  fused

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MESOZOIC LIFE

• Birds
• from Jurassic
• feathers
• (some theropods may have had feathers for
  insulation - China, 1996 (120mya))
  
• Archaeopteryx
• furcula present - most other features like small
  carnivorous dinosaurs
  
• sternum not keeled, finger and wrist bones not
  fused
  
• from dinosaurs?

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MESOZOIC LIFE

• Birds from dinosaurs?
• Bakker and others say that similarities in bones
  etc. tie the two groups

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MESOZOIC LIFE

• Birds from dinosaurs?
• Bakker and others say that similarities in bones
  etc. tie the two groups
  
• Novas and Pureta (Nature, 1997) show birdlike
  limbs in 90 my dinosaurs from Argentina

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MESOZOIC LIFE

• Marine Reptiles

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MESOZOIC LIFE

• Marine Reptiles
• Not Dinosaurs

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MESOZOIC LIFE

• Marine Reptiles
• Not Dinosaurs
• Ichthyosaurs
• long jaws with sharp teeth
• appear porpoise-like (not related)
• limbs to fins
• mid Triassic to Late Cretaceous

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MESOZOIC LIFE

• Marine Reptiles
• Not Dinosaurs
• Ichthyosaurs
• long jaws with sharp teeth
• appear porpoise-like (not related)
• limbs to fins
• mid Triassic to Late Cretaceous
• Plesiosaurs

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MESOZOIC LIFE

• Marine Reptiles
• Not Dinosaurs
• Ichthyosaurs
• long jaws with sharp teeth
• appear porpoise-like (not related)
• limbs to fins
• mid Triassic to Late Cretaceous
• Plesiosaurs
• short, fat body and tail

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MESOZOIC LIFE

• Marine Reptiles
• Plesiosaurs
• short fat body and tail
• limbs were 4 long paddles
• some had long necks

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MESOZOIC LIFE

• Marine Reptiles
• Plesiosaurs
• short fat body and tail
• limbs were 4 long paddles
• some had long necks
• Mosasaurs
• relatives of modern monitor lizard

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MESOZOIC LIFE

• Marine Reptiles
• Plesiosaurs
• short fat body and tail
• limbs were 4 long paddles
• some had long necks
• Mosasaurs
• relatives of modern monitor lizard
• paddle-like limbs
• short neck

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MESOZOIC LIFE

• Plants
• First seed plants from Devonian

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MESOZOIC LIFE

• Plants
• First seed plants from Devonian
• First angiosperms from Cretaceous
• flowers
• fruits