Which type of organisms would have evolved to feed on other organisms as a direct consequence of an increase in the amount of
oxygen in oceans?

oxygen is the first element in group 16 (via) of the periodic table. the periodic table is a chart that shows how chemical elements are related to each other. the elements in group 16 are said to belong to the chalcogen family. other elements in this group include  sulfur, selenium, tellurium,  and  polonium.  the name chalcogen comes from the greek word  chalkos,  meaning "ore." the first two members of the family, oxygen and sulfur, are found in most ores.

oxygen is by far the most abundant element in the earth's crust. nearly half of all the atoms in the earth are oxygen atoms. oxygen also makes up about one-fifth of the earth's atmosphere. nearly 90 percent of the weight of the oceans is due to oxygen. in addition, oxygen is thought to be the third most abundant element in the universe and in the solar system.

scientific consensus is : a general agreement among scientists about a scientific idea.

even though consensus implied general agreement, it doesn't mean unanimity. for example, scientists generally agree that meteor caused dinosaur's extinction. though this may not be proven yet, but it considered a consensus.

hope it