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Dino Bio Final


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first known fossil bird, transitional fossil (sitll has teeth and seperate fingers), endothermic
How do we know that birds are dinosaurs?
synapomorphies and skeletal similarities; we can see the evolutions, like with Archaeopteryx
more control than parachuting; generally small animals; some degree of climbing specialization; significantly expanded body surface
able to have a controlled fall by expanding their body surface; no major specailization; pretty small
powered flight
evolved three times with birds, bats, and pterosaurs; grants access to food in teh air as well as hard to reach places; allows an easy escape and migration, plus makes geographical barriers less of an object; takes a lot of physical energy and fuel; things that change in fliers: wing orientation, loss of body weight (hollow bones), and rigid bodies
Hypotheses about how flight evolved in birds
arboreal theory: flight began from the trees down: gliding first; no anatomical reason for glider to become powered flier, plus why were they in trees in the first place? cursorial theory: flew from the ground up; what\'s the reason? spreading wings while running would slow you down, though arm-flapping could be helpful (like in going uphill)
the geography of life (where animals live) through time
changing an animal\'s range
corridor dispersal
when there are no geographical boundaries in dispersal
filter bridge
when environmental constraints let some animals through, but not others
island hopping
when animals end up on islands, from the mainland
sweepstakes dispersal
when dispersal happens by chance; most often over large bodies of water, when the vast majority would die
characteristics of faunas evolving in isolated places
convergence (certain ecological niches filled repeatedly in isolated places), adaptive radiation, dwarfing, archaic holdovers, biased faunas
adaptive radiation
explosion of speciation when there is enough room to spread out and change
archaic holdovers
when isloation allows animals extinct somewhere else to persist because they aren\'t as threatened
biased faunas
either taxinomically (which groups are there), ecologically (the niches that they fit into), or both
Alfred Wegener
first thought that the continents might have once fit together
the single land mass that used to consist of all of today\'s continents
plate tectonics
the process of continental drift
a flora found all acress the southern continents, lending to the idea of continental drift
a freshwater reptile found in South America, Africa, and India, lending to the idea of continental drift
the concept that the polarity of the earth has reversed many times; shown by magnetically charged particles in rocks that preserve polarity and orientation at the time of formation
polar wandering curves
using paleomagnetism to find out where continents used to be located
the very center of the earth, where radioactive decay creates heat
between the core and the crust; the inner mantle is more solid
oceanic crust
teh floor of the ocean
continental crust
when oceanic crust collides with continental crust, and the oceanic crust is pushed under
evidences for paleoclimate
deposition environments, rocks of that age, original continent location, plant fossils, pollen
fair weather
controlling temperature externally, determining how active they can be
controlling temperature internally by metabolic processes, premitting sustained activity
maintaining more or less the same body temperature in 24 hours
temperature fluctuates more in 24 hour period
inertial homeotherms
animals so big that they don\'t heat up or cool down completely
vascularized/Haversian bone
when bone rings are made around blood vessels
lamellar bone
more layers of bone, less blood vessels
lines of arrested growth
shows that animal stops growing, then starts again (like tree rings, but less regular)
respiratory turbinates
folded bones in teh sinuses that prevent water loss
arguments for or against dinosaur endothermy
- must be endothermic to outcompete mammals - body posture built for high activity level - speed and activity level - if dinosaurs started small they\'d have to be endothermic, and big dinosaurs came from small ones - high volume food processing - all living endotherms have Haversian bones - fastest growthrates in endotherms (Maiasaura and T. Rex) - oxygen isotope in bone a good temperature indicator (not much variation in body temp: endotherm) - brain to body size ration - four-chambered hearts - noses: respiratory turbinates: birds have them - predator/prey ratios - faunal turnover - phylogeny (birds are endotherms)
how extinction is part of the evolutionary process
exctinction is the expected fate of an organism
mass extinction
great spike in extinction levels of many widespread and unrelated organisms
a rare earth metla; tons found at KT boundary; iridium found on asteroids
shocked quartz
structure changed by impact
small glass blobs formed by asteriod hitting earth

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