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25 Cards in this Set
- Front
- Back
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dinosaurs |
monophyletic group, of archosaurs ornithischians= specialized herbivores, stegosaurs saurischians = sauropods, theropods = birds |
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are birds really dinosaurs |
need fossils, fossils = dinosaur with four wings and feathers sequenced T-Rex collagen from bone, indicates T-Rex is related to living chicken. |
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archaeopteryx lithographica |
ancestor to birds, impression of feathers connected dinosaurs and birds feathers and reptilian traits triangular skull, large eyes and teeth limbs with claws bones hollow 3 toes in front 1 in back |
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living birds |
9700 species highly derived dinosaur |
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feathers |
keratin 5 main types contour down semiplumes filoplumes bristles most likyly evolved for insulation, thermoregulation |
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protofeathers |
feather like on dinosaur |
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did dinosaurs have one color for feathers |
plumage color of dinosaur, melanosomes control pigments, measure the shape maps onto color of melanosomes real data = hypothesis = could of have been used for signaling in sexual selection, and insulation |
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avian skull = theropods = saurischians = dinosaurs = archosaurs = diapsids |
early bird with reptilian teeth teeth lost over time jaw evolve into peak larger brain and larger eyes than reptiles avian tightly fills brain upper jaw moves relative to braincase |
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muscular gizzard |
loss of teeth, need to break down food, grinding enhanced by grit and stones moas up to 5 lbs in stones |
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pneumatic bones |
hollow very light buttresses but strong relative to other reptile bones |
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skeletal rigidity |
avian body compact and rigid by fusing bones in skull and pneumatic bones tail = plowshare bone pygostyle = is strong |
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Sternum |
breastbone is modified shaped like keel, flight muscles attach here highly modified to attach flight musclses |
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2 types of flight muscles |
1. Supracoracoideus = raises wing 2 pectoralis = provides downward powerstroke power in flight, large |
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Carpometacarpus |
Fusion of wrist and hand bones |
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feet |
perching foot basic design = 3 toes in front 1 in back 5th toe lost in birds |
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Avian Wing |
Elliptical wings= short wings, and broad High Speeds = elongate , falcons high aspect ratio wings = ideal for gliding , albatross Slotted soaring wings = eagles updrafts |
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Studying birds wing = airfoil |
samples of 40 birds, whole genome sequences produced phylogeny, most work post KT or preKT phenomena long fuse, or short fuse Diversification of living birds happened after KT extinction |
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Origin of flight |
active flight has evolved 3 times in vertebrates bats = mammals pterosaurs = extinct group archosaurs = birds crown group |
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pterosaurs |
large animals 11-12 meters wingspan same adaptations to birds 90 species |
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hypothesis of avian flight |
Arboreal Origin = Gliding as precursor problems = gliding and flapping are very different different limbs are used |
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cursorial origin |
from running along to generating lift to flying problem = have to generate lots of speed |
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WAIR |
wing assisted incline running initial step, running away from predators, using wings to run up inclines, not generating life only juveniles, baby owls do WAIR |
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loss of flight in birds |
not all birds fly, evolved over many times associated with large body size. favor selection for large body size such as in oceanic islands without predators |
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morphylogical changes with loss of flight |
Moa = lived in new zealand 12 feet tall extinction due to human hunting Keel or sternum reduced or lost wing bones are reduced feathers degenerate |
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extinction of birds on islands |
due to predation arrival of animals tightly correlated with extinction introduced animals = rats pigs , dogs Pacific Islands heavily impacted bones preserved in volcanic tube |
