Birds Flashcards
What Clade includes modern birds
Aves
Basal Theropods characteristics
-Bipedal
-elongated a-shaped necks
-hollow post cranial bones
-filamentous protofeathers
Furcula
Bone made from fused clavicles “wishbone”
Lunate wrist bone
Brings increased mobility to the wrist of birds
What type of feathers do birds need to fly
Asymmetrical feathers for flight
Feathers on one side of the cane are linger than feathers on the other side
Why did transitional bird forms have wings covered in feathers but couldn’t fly?
- Using these to glide down from trees
- Short periods of flapping flight
3.flap to help move uphill when running
Exaptation and example
A trait that initially serves one function and is co-opted for a different function
Feathers may have originated for social communication
Feathers co-opted for flight
Adaptation for communication and an exaptation for flight
Theropods capable of powered flight are known as…..
Avialae or avialans
Archaeopteryx characteristics
-skeleton looks like a reptile but has feathers
-capable of powered flight but lacked keeled sternum needed to support strong flight muscles and had restricted shoulder movement
-Had teeth (contrast to modern birds)
-lived during Jurassic, middle of Mesozoic)
Avialae
Clade that included extinct and living groups of theropod dinosaurs that were capable of powered flight
Aves characteristics and time period
-shift in body posture so that center of gravity is above the feet
-reduced tail
-loss of teeth
-a keeled sternum to which flight muscles attach
Appeared shortly before Cretaceous
Birds are derived from….
Theropod dinosaurs
Lift
Angle of attack
An upward force that causes a bird to ride based on the difference in pressure above and below the wings as a bird moves through the air
Air passing below the wings results in higher air pressure (lift) below the wing than above the wing. Lift increases the angle of attack, but only to a point
Proximal wing
Distal wing
-produces the majority of lift
-shoulder socket directed up and out increases range of motion
-ulna supports secondary feathers
-provides majority of the thrust
-elongated and fused digits support primary feathers
-lunate (curved) wrist bone increases range of motion
Skeletal characteristics of birds that enable flight
-pneumaticized bone (hollow)
-most vertebrae except cervical are fused
-keeled sternum: string flight muscles attach
-furcula: fused clavicles separate the shoulders and store energy with each wing beat
-keratinized beak with no heavy teeth
Large muscles that attach to Keel (Keel sternum)
-Supracoracoideus: raise wing
-Pectoralis: depressed the wing (power stroke)
Most feathers are ______ feathers
Contour
Primary, secondary and tail feathers
Feathers that are vaned and important to flight
Cover and protect down feathers
Flight feather characteristics
Primary and secondary
Asymmetrical and vaned (smooth webbed feather surface formed by interlocking barbs)
Streamlined body
Functions of feathers
Flight
Waterproof
Insulation
Visual signs
How do birds respire
Flow through ventilation
One-way flow of air through lungs, also found in crocodiles but not in other living reptiles
Requires two full respiratory cycles (inhale/exhale) to move air through system
Bird lung is called a …..
Does it have alveoli
Parabronchial lung
No, when air enters it passes through tube-like parabronchi
Bird inspiration and expiration steps
- Bird inhaled air #1, which travels down the trachea to the posterior air sac
- Bird echoes air #1, which travels into the parabronchial lung
- Birds inhaled air #2, which travels to the posterior air sac, and at the same time the older air move to the anterior air sac
- Bird exhales air #2, new air travels to lung, at same time, the older air moves to trachea and out of mouth
Each bird breathe travels the following route
Trachea, posterior air sacs, lung with parabronchi, anterior air sacs, trachea
Where does gas exchange take place in birds
What type of system is it
Parabronchial lung
Counter-current
-parabronchi tubes and blood capillaries lay side by side
-oxygen rich air flows in different direction than deoxygenated blood, resulting in rapid diffusion of O2 from air to blood; and diffusion of CO2 from blood to the air
-results in an almost continuous flow of oxygen
What is the most efficient respiratory system of vertebrates
Flow through ventilation of birds
-allows ability to breathe at high altitude
-ability to sustain flight
-continuous gas exchange
Specializations of birds in the absence of teeth
- Crop: enlargement of esophagus to stir food or to transport food to nestlings
- Proventriculus: anterior stomach chamber that secreted gastric juice
- Gizzard: Posterior muscular chamber of stomach. Birds swallow gravel, sand or stones that settle in girdle and grind food