Bird Anatomy Flashcards
What do most of the internal adaptions of a bird’s body help it to do?
Fly.
What are the main adaptions that permit flighted birds to fly?
Light skeletal system, light but powerful muscles, and circulatory/respiratory systems capable of very high metabolic rates.
The development of what caused birds to have a very special digestive system?
A beak.
What is ossification (osteogenesis)?
The process of laying down new bone tissue by cells called osteoblasts.
What are some theories as to how bones came to be in organisms?
It developed from tissues designed to store minerals. (cartilage stored the minerals and bones evolved from this newly-calcified tissue) Other theories include it coming to be because of osmotic protection or a protective structure.
What adaption has caused birds to have less bones and lighter skeletons than most vertebrates?
Many of their bones have fused together into single ossifications.
What is a pygostyle?
The final few bones in a bird’s body supporting the tail feathers.
Why did modern birds evolve to have a pygostyle?
It allows for much easier flight control.
What is a uropygial gland and where is it located?
The uropygial gland is located beneath the pygostyle and produces preen oil.
When did pygostyles first start appearing in birds?
In the Cretaceous period. (Around 140 million years ago)
True or false? Archaeopteryx was likely a poor flyer because it had a full tail rather than a simple, lightweight tail feather supported by the pygostyle.
True.
What is the use o the pygostyle in birds that cannot fly?
To engage in courtship displays.
Why do birds have beaks and not teeth?
Beaks are far more lightweight.
Why don’t many diving birds have bones that are as hollow as other birds?
It allows them to dive better.
What is the fastest-flighted bird when pumping its wings?
Green-winged teal.
What flightless birds have surprisingly hollow femurs?
Emus and ostriches.
True or false? Birds have less neck vertebrae than most other kinds of animals due to ossification.
False. They have more neck vertebrae than other animals.
Why do birds have specialized collarbones and/or keeled sternums?
It serves as an attachment site for the muscles used for flight or swimming.
What is the keel in regards to bird skeletons?
It is a small extension of the sternum that provides an anchor for the flight muscles.
What kinds of birds lack a keeled sternum?
Flightless ones.
In the past, what two groups were birds classified into?
Carintae (Birds with a keel) and Ratites (Birds with no keel)
Why did evolutionary scientists get rid of the ratite class?
They discovered that some flightless birds evolved from flighted birds.
What do the sternums in walking birds look like? In flying birds? In swimming birds?
Swimming Birds: Wide sternum.Walking Birds: Long or high.Flying Birds: Equal dimensions.
What are uncinate processes?
They are bony barbs that extend from the ribs.
What are some roles of the uncinate processes?
They attach scapula muscles, help to strengthen the rib cage, and increase the effectiveness of respiration.
What is the length of uncinate processes in walking, diving, and flying birds?
Walking: ShortDiving: LongFlying: Intermediate
What other kids of animals have uncinate processes besides birds?
Reptiles and early amphibians.
What kinds of reptiles exhibit uncinate processes?
The tuatara and crocodiles.
what is unique about the uncinate processes of birds?
They are bony. The uncinate processes of other species are cartilaginous.
How do uncinate processes strengthen the rib cage?
They are hooks that wrap around the rib behind them.
What kinds of skulls do birds and reptiles have?
Diapsid skulls.
What is the main characteristic of a diapsid skull?
They have two holes in their temporal bones (one on either side). They may also have other holes.
Why are lizards and snakes still considered members of the diapsid group despite having one or no holes respectively?
They remain there due to their ancestry.
What does the name “diapsid” mean?
Two arches.
What are the holes in the skull of a diapsid called?
Fenestrae.
What is the occipital condyle?
A bone on the bottom of the skull that attaches the head to the spine and body.
How many bones doe the skull of a bird consist of and what are their names?
Five bones. The frontal (top of head), parietal (back of head), premaxillary and nasal (top beak), and the mandible (bottom beak)
How much of a bird’s body weight is taken up by the skull?
1%
How are bird’s legs similar to that of a reptile?
They have a special joint known as the intra-tarsal joint.
How are the eyes of birds and reptiles similar?
They both have a circle of tiny bones around their eyes.
The pelvis of a bird is how many bones that have been fused together?
Three.
Why is the evolution of the innominate bone in the birds so significant?
It is what has allowed them to lay eggs.
What is the combined fusion of the three pelvis bones of a bird called?
The innominate bone.
Why are the leg bones of a bird the heaviest?
They contribute to a low center of gravity and help the bird in flight.
How much of a bird’s body weight is comprised of its skeleton?
5%
What percentage of a human’s body weight is comprised of its skeleton?
14%
What is the most common type of foot in birds and what is the configuration of the toes?
Anisodactyl. Three toes in front and one in back.
Barring anisodactyl, what are the other configurations and names of bird feet?
Didactyl (two front toes), tridactyl (three front toes), and zygodactyl (two in front and two in back)
What are zygodactyl toes good for?
Climbing tree trunks or clambering through foliage.
How many muscles do birds have?
175
What do the muscles of a bird control?
The legs, wings, and skin.
What are the largest muscles in a bird?
The pectoral muscles.
How much of a bird’s body weight is made up of the pectoral muscles?
25%
What muscle is responsible for raising a bird’s wing between wing beats?
The supracoracoideus.
How do skin muscles help a bird?
They adjust the feathers and help birds in their flight maneuvers.
What controls the movement in the tail?
The pygostyle.
Why do birds have tail feathers?
They give the bird a larger surface area on its tail and allow them to control their flight easier.
Beaks, claws, scales, and spurs are made of….
Keratin.
Where are scales found on birds?
On the feet.
True or false, the scales in birds are exactly the same as the scales of mammals and reptiles.
False. It has been discovered that some birds evolved or changed their scales after the evolution of feathers.
What is homology?
The existence of shared ancestry between a pair of structures, or genes, in different species. For example,
What is convergent evolution (analogous structures)?
Convergent evolution describes the independent evolution of similar features in species of different lineages. For example, birds and bats both have wings, but wings were not present in the last common ancestor of them.
What is a scute?
A bony plate overlaid with horn.
How are scutes different from scales?
Scales grow from the epidermis whereas scutes form in the dermis.
What is an osteoderm?
A scute with a bony base.
What birds have scales that overlap?
Kingfishers and woodpeckers.
What is the corneum?
The outermost layer of the epidermis.
Birds have three types of scales that increase in size. What are they?
Cancella, scutella, and scutes.
What does “caudal” refer to?
The posterior side of something.
What kind of keratin are reptile scales made of?
Beta keratin.