Thought about a hypothetical lineage of Whales descended from an Oligocene Hybrid of a Basal Odontocete and a Basal Mysticete that managed to survive into an Alternate Modern Day where Humans died out in Early Pleistocene. The abundance of Krill, Squid and Fish in the Oceans led to a Semi-Aquatic species which developed re-evolved hind-limbs complete with Melon and Baleen evolving on the Swamps of what is the Netherlands to Denmark in our timeline. Pic related is some Miocene Whales of our timeline.

I will call the species Neomixocetus sophons. Actually sapient and facultatively bipedal, otherwise with a Crocodile shaped body with a flattened beaver-like tail which it can use to prop itself up. With a duck-shaped bill too with baleen plates and a melon on top.

>>4997820 (OP)
>>4997829
But what would they eat? Even without humans I don't think there would be enough good to sustain them on swamps
Still kinda cool seeing sophonts

>>4997820 (OP)
How the fuck would they re-evolve hind limbs

>>4998224
by becoming isolated in an environment where that would give an evolutionary advantage, silly.

Very cute critter. I would love to see fan art of this creature. And how culturaly developed are? Since they are sophonts. Or still too "primitive" in your world? Also make more creatures to fit this world. How did the humans went extinct?

>>4998241
That's not how evolution works. It's not like every organism has an unconscious genetic will to adapt to the environment. they survive by chance or luck or lack of competition, and often become worse, and only when the population is large and persistent do mutations happen often enough for some of them to be beneficial and even then it's not what your logic might expect to be the beneficial "decision". Because it's not a decision.

>wouldn't it be less fit than it SHOULD be!?
yes
>most species would go extinct like this!
they do.
>evolution would take forever!
it took billions of years for multicellular life to evolve.

>>4998778
>what spec evo people think: if i put this whale in a situation where hind limbs are beneficial, it will re-evolve hind limbs
>what actually happened: the genetic mechanisms for hind limb formation are so degraded the number of mutations it would take for them to re-develop are less likely to occur than duplicating or bifurcating the front limbs, or much more likely, losing them entirely and going off track to become snake-whales

>>4997820 (OP)
whenua-4 and the derived lime plants named xyxicitoiolakikikuawewena lilililuajikakanamieieuea, which means "lime plant" in kababalamipopokilauauaeuueeai'i'i'i, their native language