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25 Cards in this Set

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monophyletic group, of archosaurs

ornithischians= specialized herbivores, stegosaurs

saurischians = sauropods, theropods = birds

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.

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

living birds

9700 species

highly derived dinosaur



5 main types






most likyly evolved for insulation, thermoregulation


feather like on dinosaur

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

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

muscular gizzard

loss of teeth, need to break down food,

grinding enhanced by grit and stones

moas up to 5 lbs in stones

pneumatic bones

hollow very light buttresses but strong relative to other reptile bones

skeletal rigidity

avian body compact and rigid by fusing bones in skull and pneumatic bones

tail = plowshare bone pygostyle = is strong


breastbone is modified shaped like keel, flight muscles attach here

highly modified to attach flight musclses

2 types of flight muscles

1. Supracoracoideus = raises wing

2 pectoralis = provides downward powerstroke power in flight, large


Fusion of wrist and hand bones


perching foot basic design = 3 toes in front 1 in back

5th toe lost in birds

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

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

Origin of flight

active flight has evolved 3 times in vertebrates

bats = mammals

pterosaurs = extinct group

archosaurs = birds crown group


large animals 11-12 meters wingspan

same adaptations to birds

90 species

hypothesis of avian flight

Arboreal Origin = Gliding as precursor

problems = gliding and flapping are very different

different limbs are used

cursorial origin

from running along to generating lift to flying

problem = have to generate lots of speed


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

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

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

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