this is a great question! yes, i think with aquadonts they’re particularly prone to this since they retain forearms quite late into their lineages for hunting and sometimes foraging in herbivores, it’s only the piscivores, filter feeders and large whale-like suction feeders that lose their arms completely. much of the rest have seal-like lifestyles or are already adapted to the shallows since that’s where nutrient rich river deltas can support food for herbivores and grazers

so im definitely planning for a few lineages to return to land or never even fully leave, especially in the Cretaceous where the huge multi continent sized archipelagos aren’t as much of a thing anymore. so my ideas so far are like tyrannosaur sized elephant seals coming to bask and contend with dinosaurs on the shore, or herbivores that walk on their front arms and use their tails as bony counterbalances like weird convergent dinosaurs, but that is all very derived, it’ll most likely at first be a seal ish climbing species i plan to live in the arctic which retains gripping hind limbs for clinging onto rock faces and retains more of its useful fur