Speculative Evolution: Herbivorous Eutriconodont
In some other timeline, a lineage of eutriconodonts (specifically, within triconodontidae) survive the kt event in asia. though succeeding as carnivores in the absence of carnivorans, one genus, cynoailurus, begins specializing as bamboo specialists.
Milk Egg
Platypodes, yapoks, stagodontids, castorocauda and even a few eutriconodonts produced otter-like forms, but never fully aquatic critters on the same level as cetaceans and dugongs.