Topic 20- Amniote Evolution Flashcards
What are amniotes?
tetrapods who have gained an extra feature that allows them to disassociate the need for water for fertilization & allows them to emerge on land
The amniote clade is ___ and ____
- the key unifying feature is an ____ ___ (ancestral condition)
mammals and reptiles
amniotic egg
Amniotes use internal/ external fertilization.
internal
-They use copulation
What does the amniotic egg provide?
- protects from desiccation (shell, chorion, amnion)
- gas exchange (allantois, chorion)
- nutrients (yolk)
4 extraembryonic membranes form the ___ in mammals. List the 4
placenta
- amnion
- allantois
- chorion
- yolk sac
Amniotes have waterproof skin (with ___). What does that do?
keratin
- reduces water lost to atmosphere
- less permeable- better protection
- must solely rely on lungs for gas exchange
The buccal pump becomes replaced with ___
- there are muscles associated with the ____ __ to ventilate lungs
lungs
- rib-cage
2 major clades of amniotes
- reptilia (including birds)
2. Synapsida (includes mammals and numerous extinct taxa)
of holes in skull used to classify amniotes. List the 3 skull types .
- Anapsid: no holes (eg turtles)
- Synapsid: 1 hole per side (eg mammals)
- Diapsid: 2 holes per side behind eye socket: removes weight (eg. replilia, birds)
The holes in skulls allow ____ to pass through to the jaw to control ___ ____
muscles
jaw movement
Non-avian reptiles include/ exclude
includes turtles, crocodiles, lizards, snakes excludes birds (they're avian reptiles)
the skin of non-avian reptiles is protected by thick, dry, ____ made of ___
- they ___the outer part
scales, keratin
shed
describe the eggshell of non-avian reptiles
it is leathery to protect from desiccation
- a few species are viviparous, with extra-embryonic membranes acting as a placenta
Reptiles are ___(ecto/endotherms) meaning they rely on ______ to maintain ________(___)
ectotherms
rely on environmental heat to maintain appropriate temperature (homeostasis)
how do reptiles control body temp?
behaviorally.
they don’t expend metabolic energy on heating, meaning they need much fewer calories than say mammals !
Reptiles care for their young ____ (except in ___)
little
crocodilians
Order Testudines (___and __) have a ____(bony dorsal and ventral shield)
Turtles and tortoises
shell
What kind of skull do turtles have? How many holes?
Anapsid (no holes other than the eye sockets)
Male testudines have an intromittent organ, which : _________
is a genitalic structure to transfer sperm to female
Why do turtles nest on land?
What do they eat?
- because their amniotic egg needs oxygen
- they are herbivores and carnivores, so they eat fish, jellyfish, etc
Tuataras have teeth ____ to ___ ___
- do they copulate?
teeth fused to jaw bones
- yes, but they lack an intromittent organ
order squamate includes ___ and ____
snakes, lizards
squamates are characterized by: (list 2)
- loosely jointed jaws and skull
2. paired hemipenes in male
what do lizards have that snakes do not? (2)
external ear openings
well developed limbs
What is responsible for no limbs in snakes?
snake enhancer
compare how snakes and lizards eat their prey
snakes: they kill by suffocation (constriction) or venom
lizards: bite and swallow prey (no not chew). a few are poisonous
Like lizards, crocs do not ____
chew
they swallow prey whole or spin it to rip off chunks
Male crocs have a single ____ ____ (like turtles)
intromittent organ
explain how crocs care for their young
maternal care:
- lay eggs in nest
- guard nest
- carry young in mouth, communicate with sound
Which of the 6 challenges of terrestrial life have reptiles solved?
- gravity
- desiccation: keratinized scales keep moisture in
- respiration: lungs are ventilated with rib muscles and a 4-chambered heart
- locomotion
- They have NOT solved temp regulation (they’re ectotherms)
birds likely evolved from _______
theropods (small, fast dinos)
are birds the first with feathers?
no, fossils suggest some dinos had feathers. Not used for flying, but display for mates
Archaeopteryx shared a common ancestor with ___
modern birds
What did Archaeopteryx have that modern birds do not? (3)
- teeth
- bony tail
- claws
Considering theropods and birds, scales are ___(homo/analogous) with feathers
homologous
similarities between theropods and birds (6)
- many theropods had feathers
- hollow, thin-walled bones
- similar respiratory systems
- brain/ heart/ other organs similar
- build nests
- incubate eggs
Class Aves is ___
birds
Birds are ___(ecto/endothermic)
describe
endothermic
- they use metabolic energy to maintain body temp
- high rate of metabolism
- feather & layer of fat help retain body heat
disadvantage of ectotherms?
in a cold environment they may not be able to digest food; b/c they can’t use metabolic energy to maintain body temp! They rely on the environment
What are the 6 derived characters of birds?
What do all of these adaptations do?
- feathers
- hollow bones
- reduced # of forelimb digits
- horny beaks that lack teeth
- gizzard
- reduced organs (poop and pee @ same time)
reduce body weight! (enhances flight)
what is a gizzard?
muscular part of stomach that grins hard food; an organ only found in birds
How do birds reproduce?
Internal fertilization (copulation) but most do not have intromittent organ (except ostriches, waterfowl)
What is the Cloaca?
a common opening for digestive, urinary, and reproductive tract
- in birds, reptiles, amphibians
- male and female birds press cloacas together to transfer sperm
young birds are cared for by mother or both parents.
Define:
1. precocial:
2. altricial:
- young may be able to feed themselves
2. born helpless and featherless
flightlessness has evolved _____many times in birds
secondarily
what challenges of terrestrial life have birds solved?
gravity desiccation respiration reproduction locomotion temp regulation (ALL OF THEM!)
