re: #599 Jimmah

Fresh -> brackish -> salt. And Cato know full well that bones wont record the process.

OTOH if you really want to understand the sorts of adaptions needed then look at current day species: whales, seals, maybe river dolphins and see how they cope with the various environments from fresh to salt.

I was looking to see if I could find anything in Nature and I came across this:

While the genital system shows many primitive features which suggest affinity to some group near the insectivores , there are, nevertheless, reasons for comparing it with the corresponding system of the ungulates, especially of the perissodactyles.

It was written in1933. I though this was an early mention of the whale ungulate connection but talkorigins says:

Later, Flower (1883) recognized that the whales have persistent rudimentary and vestigial features characteristic of terrestrial mammals, thus confirming that the direction of descent was from terrestrial to marine species. On the basis of morphology, Flower also linked whales with the ungulates; he seems to have been the first person to do so.