Exam 4 Flashcards
What class are birds in?
Aves
How many species of birds are there?
10,000
What are birds hypothesized to be very closely related to?
theropod dinosaurs
What theropod in particular is closely related to birds?
velociraptor
Why are birds thought to be so closely related to theropods?
have many skeletal characteristics in common with some theropods
Based on cladistics birds may have actually represented what?
a living dinosaur which is specialized for flight
Where are the earliest fossil birds from the Jurassic sediment from?
Germany
What is considered to be the first bird in the fossil record?
archaeopteryx
What does archaeopteryx mean?
ancient wing
What is a bird with many reptile characteristics?
archaeopteryx
What are some characteristics of archaeopteryx?
feathers
reptile head with teeth and scales
well developed tail vertebrae
What did archaeopteryx have that modern birds do not?
well developed tail with vertebrae
Why is it thought that archaeopteryx could only fly for short distances?
appeared to be relatively heavy
When did birds try to challenge the mammals for dominating the terrestrial environment?
during the tertiary period (early in Cenozoic)
What is gastornis also known as?
diatryma
What is diatryma/gastornis?
large carnivorous flightless bird
How big did diatryma/gastornis get?
7 ft in height
What are some physical characteristics of diatryma/gastornis?
fast runner
large legs and head
short wings
What kind of beak did diatryma have and what was it used for?
large hooked beak for killing prey and tearing meat
How big was the terror bird?
7 ft in height
When did terror bird occur?
about 2 million years ago
Where was terror bird found?
not America from central FL to TX
How are birds skeletal systems adapted for flight?
it is light but sturdy
Birds have pneumatic bones, what are they?
air filled cavities for the larger bones
What bones in birds are pneumatic?
wings and legs
Why are many bones in birds fused together? what is an example of a bone like that?
for strength; skull
How much does the skeleton of a 20 lb pelican weigh?
only 23 ounces
What does the trunk portion of a birds skeleton do?
forms a rigid airframe
What other bones besides the skull are fused together in birds?
vertebrae
ribs to sternum & vertebrae
What are present in between ribs in birds?
braces known as uncinate processes
Is a large keeled sternum found in all birds?
no, just most
What does a keel do?
facilitates the attachment of flying muscles
What are ratites?
group of flightless birds that rely on running (no keel)
What are birds are ratites?
ostrich, rhea, cassowary
What does the rigid trunk provide in birds?
strong structure for attachment of wings and wing muscles
What is the synsacrum?
composed of sacral, lumbar, and caudal vertebrae fused with bones of pelvic girdle
What does the synsacrum provide for birds?
solid platform for attachment of the legs
What are toes adapted for in birds?
the birds ecology
How many toes do birds usually have?
4 (mostly), 3 forward and 1 back
What is the roadrunner’s arrangement of toes like and what is it used for?
2 forward 2 back, facilitate running
What are toes and feet specialized for in many birds?
perching and/or capturing prey
How does perching work in a bird?
as a bird bends its legs on a branch, the tendons automatically tighten toes grip on the branch
Why are feathers homologous to reptile scales?
develop in similar ways, epidermal in origin
What do feathers appear to be?
slightly modified reptile scales
What would feathers be used for in the dinosaurs that did have them?
used of insulation rather than flight
What is the feather vane composed of?
bards with small hooks called barbules
What are feathers composed of?
protein keratin
What are contour feathers used for?
provide streamlined profile of body to enhance flight
What are flight feathers used for?
give shape to the wings and tail and provide lift
What are down feathers used for?
insulation
Where are down feathers located?
under the contour feathers
How do down feathers insulate?
the loose structure traps air
Describe penguins.
have more feathers than another bird due to cold climate
How many feathers can penguins have?
up to 70 per square inch
How do feathers help with buoyancy?
trap air to increase buoyancy
What other functions of feathers have?
camo
advertisement for mating and territoriality
What are special ornate feathers called?
filiplumes
Where do birds have scales?
on feet and legs (epidermal scales)
Are birds endotherms or exotherms?
endotherms
What is the body temp of birds?
40-41 celcius
What animal is the warmest vertebrate?
birds
Endothermy and flight require increased amounts of energy, so what systems have to have a decreased amount of energy?
circulatory and respiratory
What kind of heart do birds have?
4 chambered
Why is a birds respiratory system so efficient?
to sustain the energy requirements of flight and homeothermy
How do birds breathe with no diaphragm?
movement of ribs, sternum, and wings move air through lungs
How many air sacs do birds have and where are they?
about 9; in thorax and abdomen that attach to lungs
What do air sacs do?
enhance the unidirectional flow of air through lungs
What do air sacs decrease?
“rebreathing” of old air as in mammals and allows for efficiency
Do birds sweat?
no
How do birds keep cool if they don’t sweat?
air sacs help cool the bird
How do air sacs function in brown pelicans?
they also act as shock absorbers for diving birds
Where are birds larynx’s located?
top of the trachea
Is the larynx the sound producing organ in birds?
no
What does the larynx do?
modulates sound produces by the syrinx
Where is the syrinx located?
lower end of trachea where bronchi meets trachea
What is the syrinx responsible for?
sound producing, wide variations of sounds made by birds
Why is sound important in most birds?
used for reproduction and social functions
What is bird song used for?
advertise for mates and for territoriality
Describe bird songs.
composed of long, complex sounds
used by males
stimulated by testosterone
only during breeding season
What are birds sounds?
shorter sounds used as alarm calls or contact calls between birds
What is an example of how bird calls are used?
birds flying in flock will produce calls to indicate their location
Are bird calls produced by both males and females?
yes
What is the difference between the bird brain and the reptile brain?
everything is the same except birds have larger cerebrum and cerebellum
What is different when you compare bird and mammal brains?
birds cerebral cortex is thin and poorly developed in comparison to mammals
What is neocortex and do birds have it?
type of cortical tissue found in mammalian brain; no
What is the core of the cerebrum important for in birds?
helping control basic activities like eating, singing, flying, and reproductive behaviors
What is the large cerebellum important for in birds?
coordinating flight
What are the large optic lobes in birds used for?
birds have very good vision
How many pairs of cranial nerves do birds have?
12
What is the specialized structure in bird eyes and what does it do?
pecten; highly vascularized and enhances blood flow to retina while not obscuring vision with blood vessels
Describe hawk vision.
8 times better than humans due to high density of cone cells
How are hawk eyes different from human eyes?
hawks eyes are oblong compared to humans so images are spread over a larger area of retina
How do owl eyes compare to humans?
up to 100 times more sensitive to light due to higher density of rods
Why do some birds have 2 fovea per eye?
one for forward vision (pursuing prey)
one for lateral vision (scanning for prey)
Where is the fovea located in birds?
primary focus on the retina
How do birds accommodate their eyes?
by changing shape of lens
Why do birds have good hearing?
mate recognition
communication
detecting predators
What do birds have that cover their ear holes and outer ear canals?
feathers
Describe a birds ear.
tympanic membrane and single middle ear bone (columella) that connects to the cochlea
Do birds have nostrils, if so where are they located?
opening to nostrils on upper beak near the start of the beak
Do birds have larger or smaller olfactory bulbs in comparison to reptiles?
smaller
What birds have good senses of smell?
vultures
many ground dwelling birds
kiwis
What is a kiwi? Describe it.
nocturnal flightless bird from New Zealand; its nostrils are on the top of bill, probes soil with long beak and smells for food
What does a kiwi typically eat?
earthworms
What is the reproduction strategy of all birds?
oviparous
Why would developing young in the body not be advantageous for birds?
developing young in body would weigh too much, difficult for the mother to fly
What parts of the reproductive system only develop in most species of birds (females) and why?
only left ovary and oviduct develop; helps reduce weight
How does the ovary ovulate in birds?
ovulates yolk and ovum, which is fertilized near the top of the oviduct
Describe the oviduct in birds.
well developed and deposits albumin and eggshell
Does egg size and color vary by species?
yes it does
What develops reproductively in a male bird?
both testes
some have penis
How is sperm transferred within birds?
simply bringing the cloaca in contract
What does flight allow some birds to do?
long distance movements between spring and summer breeding ground and winter feeding grounds
What does long distance travel flying also allow birds to do?
maximize day length for the entire year which can enhance feeding
Why fly north to breed during spring/summer?
northern breeding areas have less predators, and seasonally larger numbers of insects to feed young; longer day lengths more feeding time
What do kidneys in some birds have and what do they do?
well developed loops of henle; help concentrate urine
What is the molarity of typical body fluid in birds? What is the molarity of birds urine?
300 mOsm; 2000 mOsm
What animals can produce concentrated urine?
only mammals and some birds
What is the major waste product in the urine of birds?
uric acid
What is guano?
formed when urine and feces mix in the cloaca
What is a major component of guano?
urea
Why is guano from birds mined from islands it accumulates on?
it is rich in nitrogen and phosphates
Where is the salt gland in most seabirds?
above the eye
What does the salt gland in most sea birds do?
produces concentrated salt solution up to 1880 mOsm, helps birds get rid of excess salt
Why wouldn’t it be advantageous for birds to bear live young?
would make the mother be too heavy to fly
How many living species are there in class mammalia?
5450
What are mammals structurally related to ?
therapsid reptiles
When do the first mammals appear in the fossil record?
triassic
What are the first mammals to appear?
small insectivores
Mammals stay small throughout what era?
mesozoic era
When do mammals radiate?
territory period in Cenozoic era
When do mammals become the dominant vertebrae?
cenozoic era
Why is mammal skin more advanced than that of reptiles?
evolved to both protective and performs a variety of functions
What does the epidermis and dermis do?
provides tough out layer of the body for protection and waterproofing
What is hair important for in mammals?
insulation
coloration
tactil sensations
protections
Why is hair better than feathers for mammals?
better insulator and less bulky than feathers
gives lower profile
allows for endothermy
How does hair help with coloration?
camoflauge and display
How is hair used for tactile sensations?
whiskers or “vibrissae”
What is an example of how hair modified for protection?
porcupine
spiny anteater
What are other structures that extend from the skin?
true horns
antlers
rhinoceros horn
Where are true horns found in mammals?
family bovidae “ruminants”
What are true horns used for?
defense and fighting between males, possibly for mate ID and attraction
What are true horns made from?
sheathes of cornfield epithelium (keratin) that surrounds inner bony layer
Are true horns normally shed?
no, although some sheep periodically shed outer cornified layers
Are true horns typically found on both males and females?
typically on males, often found on both sexes
What family are antlers normally found?
family cervidae (deer family)
Are antlers found on males or females?
only males
What are antlers used for?
defense and fighting between males and important in attracting females
Describe antlers.
composed of bone with vascularized skin “velvet”
highly branched
Do the size of antlers increase with age?
yes
Do antlers shed?
yes, complete set is grown and shed each year
When are antlers typically grown?
grown in summer and mating occurs in the fall
What is growth and shedding controlled by?
hormones (testosterone)
What is shed on antlers before mating season?
skin on antlers
When and why are antlers shed?
shed after mating season after testosterone levels decrease
What are rhino horns composed of?
dermal hair like fibers which adhere together to form a single horn
Do both sexes of rhinos have horns and are they shed?
yes and no they don’t shed
What are sweat glands used for in mammals?
help regulate body temp through evaporative heat loss
What are sebaceous glands used for?
hair follicle; help produce sebum (oil) which lubricates skin and hair
What are scent glands also known as?
apocrine glands
What do scent glands contain and why?
pheromones; mate recognition and attraction, territoriality
Scent is an important form of what in mammals?
communication
What is an example of scent being used for defense?
skunk anal scent glands; raise tail and spray potential predators
How far can skunks spray?
10-15 ft
Humans have scent glands associate with some hair follicles in what areas?
axial areas (armpits)
What have human scent glands produced?
lucrative deodorant industry as well as perfume and cologne industry
What are mammary glands used for?
nourishing young by producing and secreting milk
What kind of control are mammary gland under?
hormone
What is the function of estrogen and progesterone?
stimulate growth of mammary glands
What is the function of prolactin?
stimulated production of milk
What is the function of oxytocin in mammary glands?
stimulates ejection of milk
What do mammary glands allow for in mammals?
feed offspring regardless of food availability in environment
Mammals have a high or low metabolic rate in comparison to ectotherms?
high metabolic rate (atleast 10 times greater)
What does homeothermy allow for in mammals?
prolonged periods of high activity including nocturnal
exploit a wide range of habitats (cold regions)
What is the temp among monotremes?
28-30 C
What is the temp among marsupials?
33-36 C
What is the temp among placentals?
36-38
Why is mammalian CNS the most highly developed of vertebrates?
have largest and most highly developed cerebral cortex of any vertebrates
convolutions on cortex surface
higher level nervous functions
Mammals also have the most highly developed what of vertebrates and what does it allow for?
cerebellum; allows for more complex movements
How many cranial nerves do mammals have?
12
Are mammals the only vertebrate to thoroughly chew food?
yes
Mammals typically have what kind of teeth?
heterodont teeth
What are heterodont teeth?
different types of teeth specialized for certain functions
Teeth reflect what of the animal?
diet of animal
What kind of teeth do reptiles have?
homodont teeth
Do mammals continually replace their teeth during life? How many sets do mammals get?
no; 2 sets, primary and permanent
What kind of tooth diversity do elephants show?
tusks that are highly developed incisors
What kind of tooth diversity of walrus have?
tusks that are canines
What kind of tooth diversity do wild boars have?
tusks that are canines
What kind of tooth diversity of vampire bats have?
fangs that are incisors
What kind of tooth diversity do narwal cetaceans have?
males tusk are incisors
How are herbivores digestive systems specialized?
long intestines needed for digesting plants, some have chambered stomachs (ruminants)
How are carnivores digestive systems specialized?
shorter intestines
Do all mammals have loops of henle?
yes
What is the molarity of desert mammals urine?
up to 9000 mOsm
What kind of heart do mammals have?
4 chambered
Why do mammals have well developed muscular diaphragms?
for efficient ventilation while breathing
Are mammals the only vertebrates that use a diaphragm for breathing?
yes
What are the 3 basic groups of mammals?
monotremes
marsupials
placentals
What order are monotremes and how many species are there?
monotremata; 3 species
What order are marsupials in an how many species are there?
marsupialia; about 360 species
What infraclass are placentals in and how many species are there?
eutheria; 5000 species
What does the word monotreme refer to?
one opening, referring to the cloaca
Are monotremes the only mammals with a cloaca?
yes
Where are monotremes restricted to?
Australia, Tasmania, and New Guinea
Why are monotremes restricted to specific places?
isolated for 65 million years, since the breakup of Gondwana at the end of the mesozoic
What did isolation do for monotremes?
prevented them form being out competed by placental mammals
What is the most primitive of all living mammals?
monotremes
What are examples of primitive characteristics in monotremes?
lay eggs
have a cloaca
What are the 3 living species of monotremes?
2 species of echidna
duck billed platypus
What is an example of an echidna?
spiny anteaters
How big are adult platypus and echidna?
small to medium sized (2-10 kg)
What are monotremes?
egg laying mammals
How many eggs do monotremes normally lay?
one to two eggs
Where do the eggs travel in a monotreme?
egg travels down oviduct and into cloaca before being laid
How long does it take a monotreme to hatch an egg after incubation?
10-12 days
Are monotreme young more mature or relatively young when born?
relatively young
How long do monotreme young feed on milk from the mammary glands?
up to 5 months
Is egg laying an efficient form of reproduction?
no not compared to placental mammals
What are example of marsupial animals?
kangaroo
opossum
Where do marsupials predominate?
Australia, New Guinea, and Tasmania
Are marsupials isolated for the same reason as monotremes?
yes
What are the only placental mammals indigenous to Australia?
bats
Do marsupials also occur in South, Central, and North America?
yes
What is the only marsupial in North America and where did it migrate from?
opossum; migrated from South America
What does a marsupial embryo receive nutrition from?
uterine secretion
What forms in marsupials for a brief time prior to birth?
a primitive placenta
When are marsupial young usually born?
10-30 days after development depending on the species
Where do marsupial young go after birth?
move to pouch without help from mother, attach to nipple for nourishment
How long is the lactation period and parental care in marsupials?
several hundred days
235 days in kangaroos
What are the various stages marsupial young go through for development?
pouch
out of pouch but nursing
one in uterus
What is embryonic diapause?
when another embryo is developing in the uterus, at this time it development of embryo is temporarily halted until young leaves pouch
What is hypothesized to have happened to marsupials and placentals and why?
convergent evolution; fill the same niches and have similar body forms
What is convergent evolution?
environment is selecting for the same traits in two different groups of mammals
Where does the development of placental mammals occur?
in uterus with the support of the placenta
When was the first placental fossil found?
during the tertiary period
Are monotremes and marsupials found earlier or later than that of placentals in the fossil record?
earlier
What is the placenta?
an interface between maternal and embryonic blood, blood doesn’t actually move across placenta between mother and embryo
What does the placenta allow for?
exchange of gases, nutrients, and waste
What does the placenta shield the embryo from?
the maternal immune system
What kind of organ is the placenta and what does it produce?
endocrine organ; produces hormones that help maintain uterine condition
Do placental mammals have an efficient means of producing young?
yes
Is the total time for gestation and lactation for placentals shorter than that of marsupials?
yes
What gives eutherians a distinct advantage over marsupials and monotremes?
shorter time to produce offspring
How many orders of mammals are there?
about 30
What are the majority of the orders for in mammals?
placental mammals
