Mammals Flashcards
what skull type did mammals evolve from
synapsids
where are the openings in the skulls of synapsids
in the roof
when did synapsids start to diversify
in the permian
put these in order of their evolution: cycodonts pelycosaurs mammals therapsids
pelycosaurs
therapsids (in permian)
cynodonts
mammals
the small ectothermic, hairless ancestors to mammals evolved into the …
endothermic, furry ,mammals
why are cynodont thought to be a step in mammalian evolution
had mammal like feature in skull like teeth
its the reptile mammal connection
it laid eggs
had a secondary palate
what is diphyodonts
teeth replaced only once from milk teeth to permanent teeth
how have mammal skulls and teeth evolved
diphyodonts
bony secondary palate
single lower jaw bone
mammal evolution came from what type of lineage
therapsids
therapsids are the only synapsid group to survive past the…
paleozoic
the cyncodonts were the last therapsid group to evolve and surrived into the mesozoic… why is it considered a mammal reptile connection
laid eggs
more mammal like skull
secondary palate
what did the early mammals in the triassic look like
small, mouse sized mammals
diphyodonts
explain the cenozoic radiation of mammals
after the K-T extinction, new habitats vacated
many amniote groups vacated at end of cretaceous
mammals came in and survived
feathers define birds but what defines mammals
hair
how is the skin in mammals different than other animals
thicker
hair
how does the hair grow
continuously by rapid proliferation of cell in folicle
hair in shaft shift up
accumulate keratin, then dies
sheep and cattle have true horns… what are these sturcture wise
hollow sheath of keratinized episdermis
surround core of bone from skull
continuously grow
antlers are composed of…
solid bone once mature
seen in deer, mouse
integumentary glands come from the skin. list the type of glands and what they do:
eccrine sweat glands - cools skin
appocrine sweat glands 0 milky fluid, oily, smelly pheromone, territorial marker, warning, adrenaline
sebaceous glands - scent gland, hair follicles, greasy hair
mammary glands - modified appocrine glands
make milk in females
are all mammals viviparous
no because monotremes lay eggs
all three groups of mammals (monotremes, marsupials, placentals) are derived from…
cyncodont
when did the first mammals appear
in the jurassic
the sinodephys was the earliest known…
marsupial
when did the diversification of placental orders happen
in the cretaceous
