an extinct group of reptiles from which mammals evolved
glands that make a nutritious fluid for embryos called milk
teeth used to cut food
teeth used to stab and slice teeth
teeth used to grind up food
a young mammal's first small teeth
a large muscle in mammals that helps bring air into the lungs
mammals that lay eggs
mammals with pouches in which the young go in for protection
Mammals that have embryos that develop in mother's uterus until its body systems can function independently
time in which embryo develops within the mother
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