Ah. No. Insectoid pseudo-chordates. [Which isn't an exact translation of the perfectly precise Alternian word she uses, but somehow while "mammal" is a perfectly familiar concept to her, the class of organisms to which trolls belong does not have a close parallel in the taxonomy of most worlds from which humans come? Sorry Izunia, she's a weird bug from space.] Which doesn't actually do anything to explain the significant similarity in adult body plans, I guess.