Amniotes Flashcards
what were the 4 parts of the enclosing the pond of the amniotes
shelled egg - doesn’t need water
amnion - embryonic development
amnion - enclosing pond/fluid cavity
paleozoic amniote gave rise to all non-avian reptiles, birds + mammals
paleozoic amniote diversification gave rise to…
non avian reptiles, birds + mammals
when did amniotes diversify
carboniferous
the first terrestrial vertebrates belong to what paraphyletic class…
reptilia
what were the 2 early diversifications of amniotes
synapsids (to mammals)
sauropsids (reptiles + birds)
modern reptiles are from lineages that survived what
mass extinction in the mesozoic
why is the tuatara considered a living fossil
is the sole survivor of a group that disappeared 100 mya during the mesozoic
protoclepsydrops was the first fossil for…
synapsids
paleothyris was the first know…
sauropsid
you can classify amniotes one of two ways… what are they
original classification - reptiles, birds, mammals - under revision because reptile are paraphyletic
monophyletic way - look at diapsid splits
what are the groups of the diapsids
lepidosauria = lizs, snek, monitors, tuatara
testudines = turtle
archosauria = dinos, crocs, birds
what are the 3 derived characteristics of amniotes
amniotic egg
rib ventilation of lungs
thicker + waterproof skin
what are the 4 parts of the amniotic egg
amnion
allantois
chorion
yolk sac
what do most amniotic eggs have that limits water loss, allows gas exchange and acts as a leathery barrier against the environment?
outside shell, leathery, mineralized
what’s the main reason for the amniotes success
amniotic egg - more growth and development of larger, faster growing ambryo
no jelly layer so faster gas exchange
what are some features of the waterproof, thicker skin of the amniotes
keratinized
mostly gas proof so they no longer breathe through skin
scales, hair, feathers, claws
what impedes gas exchange in the amniotes
keratin in the skin
the changes in skin structure of amniotes is for what main reason
moving away from respiratory function of skin
the skin of amniotes tends to be… what
thicker, keratinized, less permeable to water
what is the function of keratin in the skin of amniotes
hair, feathers, claws
protects skin from physical stress
explain what osteoderms and melanphores do in amniote skin
osteo - deposits that make scales, plates or strucutre in dermallayers
melanophores - pigment w melanin in amphibians
what has tough, ry, scaley skin with a thin epidermis that sheds periodically, adapted to protect against dessication and injury?
reptiles
the thicker layer underneath the epidermic has what to help provide colour (mammals +birds only have one, reptile can have many of these things)
chromatophores
what type of keratin to reptiles have in their epidermis
beta keratin
- hard form of keratin
protects against wear in terrestrial environment
how do snakes, crocs and turtles differ in how they replace/shed skin
snakes + lizards - replace skin by shedding
crocs - grow scaled gradually to replace wear
turtles - add new layers underneath old layers
how has the breathing style changed in amniotes
use rib ventilation of lungs, muscular contraction and expansion
inspiration via enlarging thoracic cavity
how do snakes breathe? how do crocs and turtles differ?
snakes + lizards - expand ribs
crocs + turtles - move internal organs + abdominal muscles
- create -ve pressure to inhale
what the main difference between reptile breathing and amphibian breathing
reptiles - suck air in using ribs and lungs
amphibians - push air in, mouth breathers
non avian reptile jaws efficiently designed for…
crushing and gripping prey
how did the jaws in amniotes change
move from fast closure/suction feeding to large muscles to grip and chew
jaw muscles got bigger + stronger
what extinct marine reptile was notorious for being a fearsome predator that had a HUGE wishbone shaped jaw, triangular teeth and was an extreme example of reptilian teeth?
pliosaur of the plesiosaurs
list the main differences between the anapsids, diapsids and synapsids
anapsids - skulls w no temporal opening behind orbits (early amniotes and anamniote tetrapods)
diapsids - 2 temporal openings (one below cheeks, other above) - dinos, snakes, lizards, crocs, turtles lost diapsid
synapsids - single pair of temporal openings, mammal like reptiles
what skull type gave rise to dinos, snakes, lizards, crocs, turtles
diapsids
what kind of heart to amnioted have
4 chambered
some reptiles have imcomplete separation btw heart venticles… why
permits blood to bypass lungs during diving
hibernation
estivation
what are some water conservation strategies of amniotes
kidneys + urinary bladder adapted to land
most water absorbed in bladder
urine w uric acid - doesn’t need water, released as semi-solid mass of uric acid
salt glands near eyes and nose
why do reptiles and birds need salt secretion sites near the eyes and nose where mammals do not
kidneys not as effective as mammals
how is the water conservation strategy of kidneys and uric acid in amniotes different from amphibians
amphibians secrete metabolic waste as ammonia which need water
uric acid doesn’t need water
how is the lizard brain different from the brains before it
bigger cerebrum and cerebellum
better integration of sensory info + muscle control
lizards and snakes have something called the Jacobson organ…what is this
olfactory in roof of mouth, transmitted through tongue
how are mammals different from lizards brain wise
more complec emotions, memory + cortex
what is the limbic system in mammals
where emotions are processed
ring around our ancestral lizard brain regions
whats the purpose of the cortex..
helps control emotions and complex decision making
