Amniotes Flashcards
WHat did the amniotic egg allow for?
for separation from aquatic life - laying of terrestrial eggs
WHat became an issue in amniotes skulls, how was this combatted?
when muscles shorten they push iout so as brain size increased it could cause damage
evolution of holes in the cranium, so jaw muscles could develop into them, no longer pushes against brain bur into hole
WHat are the differences between the anaspid skull, synapsid skull, and dyapsid skull?
anaspid skull had no hole and thereofre no temporal bar
synapsid skull one hole so one temporal bar
dyapsid skull, 2 holes so 2 temporal bars
(for muscles contraction.
What character developed in only synapsid lineage?
reduction in ribs, development of diaphragm
What happens to salamanders (Caudata - Amphibians) breathing during movement and when stopped?
as salamander move limbs, lungs compress and expand. Air shifts from one lung to the other.
when stops does buccal pumping - throat up and down. brings in more air
What are ancestral lungs of amniotes?
balloon sac
physostymous - septa
What type of luing do synapsids have>
alveolar lungs
how do alveolar lungs work?
in and out same path, increase surface area, surfactants stop alveoli sticking together and keep moisture
WHat type of lungs do sauropsids have?
faveolar lungs
How do faveolar lungs work?
contain faveoli, which are cups inside lungs where all blood vessels are for gas exchange, air does a one-way circuit throughout.
What is a unique feature of bird lungs?
air sacs, that holds air and move during compression and inhalation
What are synapomorphies of all Lepidosaurs?
loss of lower temporal bar
epidermis shed in patches in intervals
paired hemipenis (paired penis’ left and right)
transverse cloaca
autonomy planes in caudal vertebrae
What was an evolutionary development in Tuataras?
loss of secondary lower temporal bar
What are synapomorphies of all squamata?
cranial kinesis
pleurodont dentition
loss of gastralia
What are the body forms of snakes?
burrowing
arboreal
terrestrial/grassland
aquatic
Describe body form of burrowing snakes?
short tails, blunt heads, very cylindrical, small scutes
describe the body form of arboreal snakes?
long tails (secondarily evolved)
sharp edges on belly (semicircular cross section)
Descrive the body form of terrestrial/grassland snakes?
long w/ long tails, and thin bodies cross section very small belly, gets wider (flat belly)
What are the two types of terrestrial/grassland snakes?
active
sit and wait
What are characters of sit and wait snakes?
stocky w/ giant heads
what are body forms of aquatic snakes?
laterally compressed bodies, flatter tail, almost fin like
What are synapomorphies of turtles?
keratinized scutes over plastron and carapace
carapace with fused ribs and vertebrae
plastron -> clavicle of gastralia
jaws covered w/ keratins beak
carapace covers both girdles
What are ancestral characteristics leading up to turtles?
1) Intercostal around ribs - improved ventilation
gastralia, 25 vertebrae + ribs
loss of lower temporal bar
2) reduced ribs and vertebrae
centra elongate
gastralia reduced to 1 pair
ribs break -> loose muscles
3) broadening of gastralia
4) loss of upper temporal fenestra
loss of teeth (beak)
5) gastralia form plastron
anterior trunk ribs angle posteriorly
6) complete carapace - ribs articulate
ribs cover girdles
7) neck retraction
What are the two distinctions of turtles by neck retraction?
cryptodires and pleurodires
