In this timeline of Earth, sapience developed in the ocean. The continents still exist and it’s not like life isn’t on land. It’s just that for whatever reason, sapience came in the water. And in a rather bizarre way.
On this Earth, a new breed in taxonomy appeared! The Synapsids had a branch before mammals evolved, as some Synapsids re-enter the sea. Their endothermic semi-aquatic bodies give rise to something neither mammal or reptile.
This new clade is called Thalattotheria by post Re-Alt humans.
Among the early new species, there are some with strong prehensile lips and tongues. Over even more evolutionary time, some species’ start to stretch their facial tendons and muscles into-longer, finger-like extensions. Probably from lips, whisker pads, or tongue musculature. These allow the sea beasts to start manipulating small objects, probe coral crevices, and even communicate (to an extent).
Eventually, these finger-like extensions become muscular hydrostats. What are those? You’ve seen an elephant’s trunk or even your own tongue right? That’s what these “tentacles” are. Only unlike the suckers of an octopus with fully independent musculature, they’re more like a cuttlefish’s tentacles. They only have muscular-only movements with high dexterity, evolved in pairs or bundles of four to six where lips or cheekbones would be.
Of the many species, sapience eventually emerged. One that scientists define like this:
The torpedo-like form has been a staple in aquatic evolution going back to the Ichthyosaur. This body plan includes: smooth skin without even a hint of hair or feathers for hydrodynamics, thermoregulation (by blubber, even “theoretically” in reptiles if countercurrent heat exchangers aren’t enough), a nasal system that is either closed-off or valved, eyes for peripheral underwater vision, inner-ears for sound localizations along with bone conduction and resonance chambers, and streamlined limbs that become flippers, vestigial, or merged with the tail. The dolphin today occupies this niche. It’s even been hypothesized that echolocation comes with this body plan as a package deal. As well as the intelligence to use it.
So what would happen if an animal got to have the best of both worlds? Both the power to thrive in a marine environment and the ability to change it to their will? Dolphins and octopuses both have demonstrated this ability in their own ways. So a sapient that combines them with as few drawback as possible would be ideal.
Of course a face resembling a cross between a manatee and a cuttlefish won’t be as adorable to a human as a dolphin’s. But the expressiveness that comes with muscular manipulation more than makes up for it. It gives them more personality! Especially with the trunk-like lips alongside the tentacles around the snout. This allows for an impressive display of multi-limbed multitasking.