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types of fish
- agnathic- jawless fish - lampreys
- cartilagenous- sharks and rays
- armored fish - extinct
- bony fish - ray finned fish (most common trout etc)
- lobe-finned fish- muscled fins
- lungfish- primitive lungs to breathe in shallow water
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Ichthyostega-primitive amphibian- similarities with fish
-skull structure, folded enamel teeth, homoologous limbs and fins
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Terrestrial adaptations
- -well buttressed limbs
- -interlocking vertebrae
- -amphibians developed 3 chambered heart, oxygenation from lungs
- -better sight + hearing
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Amniotic egg
- -evolutionary breakthrough
- -self contained nutrients and waste system
- -hard shell protects yet allows for gas exchange
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Skull types
- Anapsids - no extra holes (turtles)
- Synapsids - low on skull (mammals)
- Euryapsids - high on skull (marine reptiles)
- Diapsids - 2 extra holes (crocs, snakes, dinos, birds)
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2 types of dinosaurs
- ornithischians- bird hipped - triceratops, stegosaurus, hadrosaur
- saurischians - lizard hipped - birds evolved from them
- (feathers for thermo regulation)
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2 types of dinosaurs that evolved from Saurischians
- Theropods - bipedal carnivores
- Sauropods - huge, four legged herbivores
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ectotherms
rely on external temperatures to regulater their body heat
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endotherms
create own body heat from fuel
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poikilotherms
variable body temps (hibernating mammals)
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homeotherms
constant body temperature (internal metabolism regulates temp)
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Evidence for dinosaur endothermy
- -relationship to birds
- -Haversian canal present in mammals found in dinos
- -Upright posture- bipedal locomotion
- -found in high latitude ranges
- -require los of fuel (made up 2% of fauna, lots of prey available)
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Evidence for meteor impact causinf extinction at the K/T boundary
- -abrupt lithological change
- -impact site in Yucatan, Mexico
- -high levels of iridium (solar element)
- -shocked quartz from impact
- -andesitic rock 65 m. yrs partially melts, droplet in air- microtites
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Alternative theories for extinction
- Vulcanism from Deccan Traps in India
- Combination of vulvanism and sea level fall
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