Last time, in 40k Minor Xenos Quest: A Struggle To Survive Redux :
A Dominant Matriarch had evolved a mutation on an homeotic gene leading to bipedism - this gene happens to be ported on sexual chromosomes, making all female descending from this first bipedal female bipedal themself.
It's been two generations, and a handful females are porting the new mutation.

By the mechanics of egg-sharing, those females are found all around <span class="mu-s">the crack</span> as well as adjacent frozen peaks. (You) are one such matriarch.
Right now, you are lonely : far from the aesthetical favored criterion of the rest of the race, you were rejected as a malformed youngling.
This is only a setback, as (You) are the dominant. Your bipedal position let your Ichor reach your brain more easily. Ear farther. Exact more strength with your now-free, dexterous limbs.
(You) are the inevitable future of the Under Hunter. But, for now, your tribe is a mere dream in the head of a lonely Under Hunter.

https://suptg.thisisnotatrueending.com/qstarchive.html?searchall=40k+Minor+Xenos+Quest
Under Hunter current sheet : https://pastebin.com/tKCdQ6Vt