Mammals Part I Flashcards
How many species of mammals are there?
5000 species
what the 3 unique features of mammals?
- hair: insulation, camouflage, sensory and defence
what the 3 unique features of mammals?
- sweat glands
what the 3 unique features of mammals?
- mammary glands
skull types of amniotes: anapsids
turtles
skull types of amniotes: synapsids
terapsids and mammals
skull types of amniotes: euryapsids
extinct marine reptiles
skull types of amniotes: diapsids
dinosaurs and birds
what is the key difference between skull size presence, size and number of temporal fenestrae:
holes that provide more surface area for muscle attachment
when did true mammals evolve?
around 225 mya - Triassic
Different morphological states of middle ear of mammals: MME
mandibular middle ear
Different morphological states of middle ear of mammals: TMME
transitional mandibular middle ear
Different morphological states of middle ear of mammals: DMME
definite mammalian middle ear
what did the development of the middle ear allow?
mammals to hear at higher frequencies than reptiles
mammals did not radiate until the extinction of??
dinosaurs
the ambulocetus is the ancestor to
whales
megatherium were
herbivourous and elephant sized
- giant ground sloth
how did smilodons go extinct?
hunting of humans
features of mammalia
endothermic
features of mammalia
advanced nervous system
features of mammalia
internal fertilization
features of mammalia
unlike reptiles and fish, mammals also show heterodonty
heterodonty
different teeth specilized for tasks
features of mammalia
specilization in teeth among species = varied diets
features of mammalia
4 chambered heart
Prototherians
- monotremes
- egg laying
- egg incubation until hatching
- have mammary glands
- playtpus, echidna
marsupials
- pouched
- early birth, fetus completes development in pouch
Eutherians
- placental
- embryo retained in female reproductive tract
where did platypus (PERRY THE PLATYPUS) originate from?
eastern australia
what do platypus use their bill for?
use bill to dig for custaceans and worms
how many eggs do playpus lay?
2-4 eggs
the platypus bill acts like a
sonar system
- similar to electric fish, bill of playtpus has a mechano- and electro receptors that allow organism to create a map with field lines that determine the location of prey
Echidna are known as
“spiny anteaters”
Marsupials do not
lay eggs
marsupials have short ___ and long ___ ___
gestation; nursing periods
what is the largest marsupial carnivore?
tasmanian devil
why are Tasmanian devils extinct?
due to hunting and dingos
94% of mammals are
eutherians
eutherians have an
amniotic egg retained in the female reproductive tract
Eutherians are often referred to as
placental animals - but some marsupials have placentas too
placenta
organ formed by the embryo and mother after implantation
how was the placenta formed?
by extra-embryonic membranes and uterus lining of the mother
what occurs in the placenta?
gas, nutrient and waste exchange between the mother and the embryo
how do substances pass between the mom and fetus?
by diffusion
what moves across the placenta?
- small molecules
- urea
- nutrients
- hormones
- alcohol and drugs…
