Tetrapods Flashcards
Where did tetrapods evolve from?
Lobe-finned fishes
Three characteristics showing that Amphibians are still aquatic
- Reproduction happens in water; mostly external fertilization
- Eggs are un-protected and hatch larvae with gills not lungs
- Skin is thin, moist, and permeable
Three characteristics showing that Amphibians are becoming terrestrial
- Tetrapod skeleton grows strong, spine becomes more rigid
- Loss of lateral line and development of sound and olfaction reception
- Develop head mobility and a tongue to handle food within mouth
Apoda or Caecilians
- Snake like
- Most blind as adults
- Breathe by skin and lungs
Which amphibian reproduces internally?
Apoda (tadpole-like larva)
Caudata or Urodela
Salamanders (with tail)
- Respiration by gills as young
- Respiration by lungs + skin as adults
Anura or Salientia
Frogs and toads
- NO paedomorphosis
Paedomorphosis
Retention of larval morphology after reaching adulthood (no metamorphosis)
Which amphibian goes through paedomorphosis?
Salamanders
Frogs vs. Toads
Frogs: thinner skin, attached to water, produce masses of eggs, normally jump
Toads: drier bumpier skin, less dependant on water, produce line of eggs, normally crawl
In frogs & toads; what is the male’s part in fertilization?
The male attaches to the female’s back while she lays eggs; adds seminal fluid
5 main innovations for reptiles
- Egg with amnion
- Dry scaly skin
- Excretion of uric acid
- Copulatory organ
- Better jaws + stronger skeleton
Anapsids
0 temporal openings
Synapsids
1 temporal opening
Diapsids
2 temporal openings
What reptiles are anapsids?
Turtles
What reptiles are synapsids?
Several extinct reptiles + therapsids
- Dimetrodon
What reptiles are diapsids?
- Lizards
- Crocodiles & alligators
- Snakes
- Birds
Birds main adaptions
- Feathers
- Skeleton; flight muscles
- Temperature regulation
- Respiration
- Reproduction and behaviour
Birds: Feathers
- Derived from reptile scales
Birds: Skeleton; flight muscles
Bones are porous, light and strong
- vertebrate fused to ribs and skull is fused in one piece
Birds: Temperature regulation
Endothermic: body generates its own heat
Homeothermic: body maintains a constant temperature
What are the first known mammals?
morganucodontids
Origins of mammals
Descendants of Therapsids
What differentiates a mammal from other vertebrates?
- Major skull and dentition modifications
- Ear apparatus
- Hair, lactation
- Changes in limb posture
Prototherians
- Order Monotremata
- Platypus & Echidna
- 1 cloaca
- pouch
- absence of nipples
- lactation
Platypus
- Protherian
- Order Monotremata
- Semi-aquatic
- Produces venom via crural system (only males)
- Electro and mechanoreceptors on bill and skin
Echidna
- Protherian
- Order Monotremata
- Mechano and thermoreceptors
- Mucus glands
- Curls in ball
Metatherians
- Short gestation period
- Inefficient placentas
- Extremely altricial babies
- Marsupials (pouch)
- long lactation period
- Hair
e. g. Kangaroo
Eutherians
- Some don’t have hair as adults
- Altricial or precocial babies
- Short lactation period
- Complex and advanced social behaviours
Birds: Respiration
- Well-developed lungs and blood irrigation
- With air sacs (hold fresh air)
- Fly
Birds: Reproduction & behaviour
- Well-developed brain for flight and visuals
- High developed behaviour and visual displays during mating
- Females only have left ovary
Flightless birds
- Evolved from several independent origins
- Most usually, evolved as a response to lack of land predators
- Pelvic bones enlarged and sternum reduced
e. g. Ostrich
Seabirds
- Less colorful
- Waterproof feathers
- Live longer, reproduce later
- Salt glands
- Lost ability to fly
- Wings shaped as fins
Reptiles: Egg with amnion
Thin membrane with fluid that protects the embryo
Reptiles: dry scaly skin
Heavier, thicker, non permeable
- Protect against desiccation
- Formed from epidermis
Reptiles: excretion of uric acid
Highly concentrated urine
- Minimizes loss of water
Reptiles: copulatory organ
Internal fertilization is now necessary
- Reproductive organs in cloaca
Reptiles: Skeleton
More efficient for chewing and bigger prey (jaws)
- Larger and heavier bodies
