What are the CRB animal-alien races supposed to look like?

[Pennate]

I haven't kept up with Starfinder since before it launched, but I was wondering if the physical details of some of the core races were ever definitively explained. To me, the art direction for these races seemed contradictory and confusing, as significant aspects of their descriptions were rendered inconsistently in promotional pieces.

-Ysoki: Ysoki were frequently depicted in the fashion of the traditional D&D / Pathfinder ratfolk, but they also appeared as humanoids with the body proportions of halflings and the oversized heads and tails of cartoonish mice. I believe both versions were shown at an approximately equal rate. Do we have any in-universe explanation for these physical differences? If not, which is the ysokis' canonical appearance?

-Vesk: Most pre-release art showed this race as a fairly standard lizardfolk-style creature. However, I distinctly remember one piece of art in a blog post featuring a bust of a male vesk that looked like a muscular human with pastel green skin and a darker, scaled, reptilian head. Has this drastic change in appearance appeared in any Starfinder releases since then, or was it just the work of a misguided artist?

-Shirren: As I recall, shirren displayed some sort of sexual trimorphism, yet all shirren in the pre-release art looked almost identical. Have we seen all three sexes together? Are they physically distinct, or did Paizo invoke the Sci-if trope of "humans being unable to distinguish between alien sexes?"

[BigNorseWolf]

Re ysoki they're not even a singular race, with a lot of branching offshoots and variety. They come from different planets and its a matter of either convergent evolution and or common origin a ways back but with plenty of time to evolve differences. " "humans being unable to distinguish between alien sexes?" is oddly in effect with Ysoki. (My envoy wears a giant pink bow on her tail, because humans care but are bad at telling)

Vesk The near space book mentions there's a few races of vesk, some are psycic cave dwellers, some spit poison etc. So something more humany isn't out of the question.

Shirren only they know the difference

[Dracomicron]

Anthropomorphic Ysoki are even a character option in the COM.

[Metaphysician]

I generally assumed that most species have as much variation in morphology as humans. Some have more. Now consider how much variation in skin color, hair color, height, weight, body shape, etc, humans have.

The main difference is that some species, these variations are hard for the human eye to discern. To a human, the ridge profile of a Shirren thorax might look like just random ridges; to a Shirren, they fall into broad but distinct categories in the same way a human might distinguish hair color.

[Pennate]

I might be late here, but this has been very informative. With a universe of aliens ready for description, I didn't expect Paizo would spend any time on sub-races for the Core options. I also didn't know that Ysoki was a collective name, but that makes sense given their relationship with Golarion ratfolk; the fact that there were two races on separate planets in the same solar system that nevertheless evolved identically was my favorite thing about ysoki in PF1E, as it it called to mind the theory (whose name unfortunately escapes me) that life across our universe would always evolve along certain optimal pathways, producing highly similar organisms on every planet capable of supporting life.

Also, that is a great point, Metaphysician. I didn't consider using human morphology for context in this situation, but that makes my issues much easier to resolve..

[Claxon]

Ysoki/Ratfolk appearing in multiple planets is just as likely to be caused by the same thing that has humans popping up on multiple planets as some convergent evolution.

As for why some Ysoki look more human...it is actually a character trait option like Dracomicron mentions. I can' think of a human equivalent, but while they're limbs are a bit different they're still Ysoki at their core.