Lesson 9 Flashcards
crown tetropods
- classified as the nearest living ancestor of all living tetropods
- have fewer than or equal to 5 digits
- have the presence of an occipital condyle
- originally – all tetrapods were thought to be carniverous
if you look at exant lissamphibia –> no adults eat plants
what is the purpose of an occipital condyle
like the ball and socket – it enables up and down motion
- aquatic fish do not have this and can’t move their heads up and down
amniotes
- we share a more recent common ancestor with a lizard than has to a salamander
(amniotic eggs sac) - having this amniotic egg stopped the dependance of water for reproduction
- have waterproof skin
- find at least 2 sacral divisions for fossil amniotes
- lateral phalanges of pterigoids
- an astralagus
key derivations of amniotes
- having an astralagus (ankle joint)
- having an amniotic sac
roamers gap
- gap in the carboniferous period (gap in tetrapod fossil record)
- very few terrestial rock outcrops
- as a result - early tetrapods are not really known
temnospondyli
- range broadly in size from cm to the size of aligators
- have aquatic larvae
^^^ and most were semiaquartic
early stereosponduli
- presence of sturdy zygapopheses
- interpterygoid vacuity
- lived in lowland swamps – compared to crocodiles
importance of sturdy zygapopheses
greatly resist torsion and other forms of vending
interpteryoid vacuity
- big opening in skull
- 2 occipital condyles
disaurophoydia
- includes batracia (frogs and salamanders)
basal amniote skull
paired dermal bones in skull
- gonna really form the basics for formation of phenestrae
^^^^ which is the hole inside the skull through which muscles pass
hylonomus
- extinct
- early amniote
- reveals the 4 regions of vertebral column quite well
basic amniote character
- lateral flange of pterygoid
- the second vertebra forms a unique vertebra (axis) first one is the atlas
- ankle mesotarsal joint
- separation of axial musculator and appendicular musculature
- at least 2 sacral vertebrae
- lateral flange of pterygoid
- important origin for muscle
- for a greater body size – it helps to have a good jaw action for catching prey
- the second vertebra forms a unique vertebra (axis) first one is the atlas
process that articulates (dens) enables site of side to side movement
ankle mesotarsal joint
thought to be associated with the new skill of feet and to be used for locomotion
– ^^^ prior — feet and hands were more like holdfass
albumen (amniotic egg)
- water in the sac
- provides shock absorption
yolk sac (amniotic egg)
provides a lot of nutrients and energy and fats
- non amniotic eggs have a sac
- but amniotic eggs have 3 additinal extra-embryonic membranes that funtamentally make it an amniote
what did these thick extra embryonic membranes do
they elevated the speed with which metabolic respiration could occur – which allowed for a larger egg – larger hatchling – and ultimately a larger adult
coastal ventilation of the lungs (amniotic egg)
- amniotes have evolved this mechanism for bentilatio of lungs
- makes use of muscles between ribs to change the volume of the inside and pump air in and out
- much more efficient than buccal pumps of nonamniotes
^^ musculature of buccal pumps is not needed – can run while breathing
efficiency of ventilation lungs enabled the evolution of longer necks – PROBLEM
- dead air space
- necks do not have a hgas exchane area and thus it is viewed as ineffecient
- but because of this coastal ventilation – the inefficiency of long necks is countered
— neck allows for animals to reach lofty heights, but also provides sapce for the elaboration and branching and nerves extending to the limbs
———– dexterity and fine motor movement for limbs
———— the capactiy to write —— requires great deal of elabortation of nerve fibers
patterns of amniote temporal fenestra
- holes on the side of the skull through which muscles pass — ex — important jaw muscles
- form foundation
- hole gets greatly modified, even lost
evolution of fenestra
- evolved twice
- synapses and diapsids are not from an original one whole organism ???
basal turtle
- extant turtles have no fenestra
- there ^^ is discussion over where they belong becasue of their lack of fenestra — but the question was answered —- there were early turtles with a diapsid condition
^^^ can call extant turtles anapsids (no hole)
t/f post orbital bar has been lost in mammels
true
diapsid
lizards –> lose lower temporal bar
snakes – losed lower and upper temporal bar (lower and upper phenestra merge)
- birds
- extinct dino
synapsid condition
one hole
diapsid condition
2 holes
a flat skull acts as a bellose
- flat thing that blows wind
- does not enable complex jaw movement
range of motion of any muscle is directly proportional to hiw ling that muscle is
- would have been selection between tall skull — allowing for longer muscles of jaw motion
——- but if it strains the skull too much – its not really able to support the range of motion
BUT ——— a small hole would have relieved some of that stress ———- providing elasticity
THEORY of small hole
originated as a small hole to relieve stress — larger hole for muscles arouse of out that – allowing them to buldge outward and wrap around skull
ankle evolution
3 tarsals fuse to form astralagus
- forming new joint
- some groups deviate and fully devolve
- food more acting as a lever
more amniotic egg
- presence of shell with pores
- shell doesn’t need to be mineralized
- a lot have kind of this soft-leather kind of egg
- enables the developing embryo to bypass that larval stae
- there are no larval stages in amniotes
- no gills – exchange gases by diffusion through pores of
aquatic amniotes
- usually come ashore to lay eggs
- or could be viverous
earliest mammals
thought to be egg legging
all amniotes have
internal fertilization –> due the presence of the sell
- many have evolved a penis to make this possible
tradeof for gasses passing readuly
- not just CO2 and O2 that are passing through
- microbes also pass through
- can compromise the life of the embryo
bird and egg susceptibility
female lays her eggs then the egg is immediately susceptible to the invasion of microbes through pores of the shell
- by incubating –> she raises the temperature to about 39 degress celcius and the microbes die
if the bird lays more than 1 egg
- vast majority can only lay 1 per day
- if ou have a 4 day spread of egg laying – 4 day spread o f hatching
—– there will be a runt - runts cannot compete with the older birds
- most birds don’t start incubation right away so that way you don’t have a competing older and younger bird situation
TRADEOFF of incubate
you can incubate early to make sure everyone hatches but there will be a separation of births and most likely a runt, or you can wait to incubate so everyone hatches together (first ones to be born may not hatch)
how many eggs you lay
- if you lay 1 – not a problem
- 2 eggs - one day apart, not gonna be a big deal
ex: 10 eggs —— tremendous spread of hatching
latitudinal variation
more affect in the tropics bc of warm climates (not good when it is too warm for incubation)
latitudinal variation of clutch size
birds of higher latitude lay more eggs –> becasue the microbial threat is not as large
