When did whale ancestors begin living full time in the water?

It was 50 million years ago that the ancestor of the whales began to lived on the edges of the ancient Tethys Sea according to the exhibit in the museum of New Zealand.  The ancestors of whales were living in the land, but were mainly eating fish.

Basilosaurids are ancestors of the whales that inhabited the oceans approximately 38 million years ago. They did not live on land and were 18 meters long. they were discovered in 1840 and initially confused with a reptile.

They existed from the end of the Middle Eocene to the beginning of the Upper Eocene. The researchers believe they were the first fully aquatic cetaceans and gave rise to modern cetaceans.

some fungi obtain their nutrients from a living host (plant or animal) and are called most biotrophic fungi have fairly narrow host ranges—they are specialized on a limited called rhizomorphs that allow the fungus to grow from one tree to another. ascospores are formed inside a sac-like structure called an ascus. so your answer is a

emerging idea only occurs as a raw idea that could appear out of nowhere. meanwhile, to reach scientific consensus , that idea must be structured and tested over and over again through various experiments. the scientific consensus transforms the raw idea into idea that is more reliable through the process of scientific elimination.