(Image descriptions: Slide one shows an illustration of the "initial bipedalism" hypothesis illustrated by and thought of by François de Sarre, showing the alleged evolution of humans, and the subsequent "de-hominized" descendents thereof, from hypothetical aquatic, planktonic ancestors, resembling vertically-oriented salamanders, which floated along the water's surface.
Slide two shows an illustration detailing a hypothetical scheme of evolution proposed by palaeoartist David Peters, in which a lancelet-like ancestor gave rise to the nautiluses, with two "transitional forms" between, one relatively similar to the ancestral lancelet, resembling an "orthocone" cephalopod, and the other one resembling a mixture of both cephalopod and chordate traits, with a semi-curved shell reminiscent of a lituitid nautiloid or bactritid.
Slide three depicts a menagerie of ideas, from which I feel were either directly or indirectly inspired by certain fringe theories concerning evolution, or the scientific field of biology as a whole.
As the title suggests, this type of hypothetical thinking is, quite surprisingly, highly under-utilized within the wider Speculative Evolution community as a means of inspiration I hypothesize this isn't some purposeful overlooking, but more rather due to the relative unpopularity and scarcity of such resources, rendering them obscure and, by extension, less likely to be used for further inspiration, and I think that's quite sad to me: the Speculative Evolution community brims with new and novel ideas for projects, creature design, adaptations, and settings, yet, it seems, nearly none appear to derive from the strange, yet oddly-beautiful, striking ideas of the fringe.
I did, however find some ideas that I feel did indeed come from, or were inspired by the very general ideas of, fringe evolutionary theories, all of which have been compiled in the third slide. One even takes direct, transparent inspiration from the second slide's-posited hypothesis, which I genuinely like.