# data[].attributes.headline
Teeth of different types with a living core

# data[].attributes.subject
Teeth of different types with a living core

# data[].attributes.headline
Most give birth to live young and feed young with milk from mammary glands

# data[].attributes.subject
Most give birth to live young and feed young with milk from mammary glands

# data[].attributes.headline
Sperm passes into the female for internal fertilization

# data[].attributes.subject
Sperm passes into the female for internal fertilization

# data[].attributes.headline
Four legs in most or two legs and two wings/arms

# data[].attributes.subject
Four legs in most or two legs and two wings/arms

# data[].attributes.headline
Lungs with alveoli, ventilated using ribs and a diaphragm

# data[].attributes.subject
Lungs with alveoli, ventilated using ribs and a diaphragm

# data[].attributes.headline
Skin has follicles with hair made of keratin

# data[].attributes.subject
Skin has follicles with hair made of keratin

# data[].attributes.headline
Sperm passes  into the female for internal fertilization

# data[].attributes.subject
Sperm passes  into the female for internal fertilization

# data[].attributes.headline
Lungs with para-bronchial tubes, ventilated using air sacs

# data[].attributes.subject
Lungs with para-bronchial tubes, ventilated using air sacs

# data[].attributes.headline
Do not maintain constant body temperature

# data[].attributes.subject
Do not maintain constant body temperature

# data[].attributes.headline
Teeth all of one type (compare with mammals)

# data[].attributes.subject
Teeth all of one type (compare with mammals)

# data[].attributes.headline
Sperm passes into the female through internal fertilization

# data[].attributes.subject
Sperm passes into the female through internal fertilization

# data[].attributes.headline
Lungs with extensive folding to increase surface area

# data[].attributes.subject
Lungs with extensive folding to increase surface area

# data[].attributes.headline
Impermeable skin covered in scales of keratin

# data[].attributes.subject
Impermeable skin covered in scales of keratin

# data[].attributes.headline
Do not maintain constant body temperature

# data[].attributes.subject
Do not maintain constant body temperature

# data[].attributes.headline
Larval stage that lives in the water and adult that lives on land

# data[].attributes.subject
Larval stage that lives in the water and adult that lives on land

# data[].attributes.body
Eggs and sperm released for external fertilization

# data[].attributes.body
Four legs when adult

# data[].attributes.body
Tetrapods with pentadactyl limbs

# data[].attributes.body
Tetrapods with pentadactyl limbs

# data[].attributes.body
Simple lungs with small folds and moist skin for gas exchange

# data[].attributes.body
Soft moist skin permeable to water and gases

# data[].attributes.body
Do not maintain body temperature

# data[].attributes.body
Remain in water throughout their life cycle

# data[].attributes.body
Eggs and sperm released for external fertilization

# data[].attributes.body
Swim bladder containing gas for buoyancy

# data[].attributes.body
Fins are supported by rays

# data[].attributes.body
Scales are covered by an operculum, with one gill slit

# data[].attributes.body
Scales are bony plates in the skin