During which eon did oxygen begin to build up the most in Earth’s atmosphere? a.)Phanerozoic b.)Proterozoic c.)Hadean d.)Archean

phanerazoic

if there was no oxygen then why were there dinosoars

one characteristic that is shared by all is a soft body. many

of these invertebrate animals also have an outer shell to protect their

body. oysters, clams, snails, and mussels are all mollusks. so are octopuses, squids, and slugs. mollusks live on land and in freshwater.