Card Set Information
4 modes of air travel
Dispersing spores (passive flight) evolved in the __ era
Oldest spores = Ordovician
Insects with flight evolved in the __ period
Parachuting vertebrates evolved in the __ period and were diverse in the __ period
Pterosaurs evolved in the __ period.
Birds evolved in the __ period
Bats evolved in the __ period
Why did flight evolve in animals?
move from place to place
access to new food sources/unoccupied niche
The first animals to fly were
: flying Hexapods (common by late Carboniferous)
flight only occurs in adults
origin of flight in insects
possessed walking legs and exites (homologous with exopods?)
evolved from gill/swimming legs
didn't sacrifice "walking limb" for wings
In insects, wings were pre-adapted for
Small wing aspect ratios require rapid strokes.
primary requirements/demands of active flight
strong, yet light body (skeleton)
modified pectoral girdle capable of power stroke
modified forelimb capable of supporting useful wing
Cursorial Flight Hypothesis among birds
began by running and flapping from the ground
Terrestrial theropods used wings to catch prey "insect nets" or
flapping and fighting during social activities
problem with hypothesis
: Theropods could climb.
Arboreal Flight Hypothesis among birds
began by climbing and jumping from trees
Theropods climbs trees to avoid predation and forage
problem with hypothesis
: Climbing damages feathers on terrestrial theropods.
1st vertebrates capable of true/powered/active flight
Pterosaurs (Late Triassic)
locomotion of Pterosaurs on ground
ability to walk is debatable:
Fused pelvic girdle suggests bipedal locomotion.
Scrawny hind limbs with "sideways" posture suggests quadrupedal locomotion
origin of birds
evolved by the Late Jurassic from Theropod dinosaurs
There was a low diversity of birds until the __ period
(very successful group)
A good candidate for sister taxa of birds are the
Dromeosaurids originated in the __ period
Late Cretaceous (younger than first birds)
Similarities between first birds and Dromeosaurids
terrestrial (couldn't fly)
general adaptations of birds
hollow bones (pneumatic)
short stout humerus
wing supported by elongated radius and ulna
fused clavicle AKA furculum
first "true bird"
Archaeopteryx (Late Jurassic)
similarities and differences between Archaeopteryx and modern birds
: feathers and furculum
: fingers on wings, small sternum
purposes of developing wings
display = social activity
characteristics of Archaopteryx that fit the Cursorial hypothesis
tail feathers not for flight
fused clavicle (furculum)
claws for catching prey
characteristics of Archaopteryx that fit the Arboreal hypothesis
retroverted hallux capable of perching
fore limb clawed phalanges could be used for climbling
Birds show a gradual increase in flying during early evolution.
Later birds improved on the basic flight adaptations and become better flyers.
Penguins and other divers use the basic stroke "flying underwater"
Other birds use their feet for diving
The hypothetical ancestor of bats would have been
a nocturnal, insectivorous, arboreal glider
flight adaptations of bats
keen senses (echolocation or good eyesight)
modified pectoral girdle
reduced radius with enlarged humerus and ulna
: membrane between hind limbs for stabilization and gliding
membrane supported by the arm and several elongated fingers, which help produce greater thrust