Mammals Flashcards
What is the earliest synapsid (mammal like reptile)
pelycosaurs (includes Dimetrodon sp.)
What are characteristics of pelycosaurs
dominant terrestrial vertebrates of the late Paleozoic (300-251 million years ago
vertebrae supported large snail-like structure, possibly for thermoregulation
teeth show beginnings of heterodont (specialized) dentition, as opposed to homodont detention of other reptiles
what are therapsids
one group of carnivores pelycosaurs gave rise to Therapsids- they had an efficient erect gait with upright limbs positioned beneath the body
Cynodonts
what mammalian features did they possess
high metabolic rate, endothermic
diaphragm
three middle ear bones
at least vibrissae (whiskers)
what are skull characteristics for mammals
increased jaw musculature
heterodont, diphyodont dentition
secondary bony palate, enabling animal to suckle and breathe at the same time, also to eat and breathe at the same time
explain whales
closest extant relative to hippopotamus
many intact fossils skeletons discovered in Egypt
primitive whales, in the last stages of losing their limbs
what are the 6 mammal characteristics
3 middle ear bones
hair
sweat glands
mammary gland
diaphragm
neocortex in the brain
Hair
where is follicle located in the skin
dermis
what is keratin
cells are carried away from their source of nourishment and die turning into keratin which meakes hair
what are the two kinds of hair
under hair
guard hair
what does underhair do
insulation
dense in aquatic mammals, keeps them from getting wet
what does guard hair do
protection and coloration
what is whale hair
do have hair
but only few sensory bristles
Skin gland what is sebaceous glands
produce sebum
keeps hair and skin moist and pliable
What do scent glands do
produce chemicals for communication (territory, repro)
in various locations (head, penis, anal, legs, armpits)
What are the two kinds of sweat glands associated with the skin of mammals
eccrine
apocrine
what do eccrine gland do
evaporative cooling
sweat gland
what does apocrine gland do
associated with repro cycle (developed during puberty)
sweat gland
what are mammary glands
probably modified apocrine gland
occurs on all female mammals and in a rudimentary form an all-male Mammels
make milk
what are antlers
develop in the spring and are shed each year
composed of dermal bond, usually only in males
what is a pinnae
external ears
used to catch sound, thermoregulation
what are whale teeth like
baleen
what is insectivore digestive system
short intestine
NO CECUM
diet doesnt require prolonged fermentation
explain nonruminant herbivore digestive system
cecum is a fermentation chamber harboring microorganisms that break chemical bonds of cellulose
simple stomach, large cecum
some exhibit coprophagy (eat own shit)
explain ruminant herbivore
4 chambered stomach with large rumen (for microbial digestion)
cud formed in rumen retuned to mouth for chewing then back to rumen
relatively long intestines
explain carnivore digestive system
short intestine and colon
small cecum
no need to feed continuously as herbivores do
