How should I handle fauna in my worldbuilding
I'm working on a low fantasy world and I'd love some feedback on the overall coherence of the species mix, as well as thoughts on how to handle sapient non-humans in a way that feels like actual species rather than just humans wearing animal costumes.
The Setting at a Glance
Magic is either minimal or absent — I haven't decided yet. What I have decided is that the world is roughly 4x the size of Earth in terms of both land and sea area, and there's a substantial hollow-earth style cavern network beneath it that functions as its own ecosystem zone. The world supports life across a much wider temporal range of species than Earth currently does, which is a deliberate choice — I just like deep-time fauna existing alongside each other.
The Fauna Mix
The deepest survivors are Permian-esque holdovers — think Lystrosaurus-type dicynodonts persisting in isolated refugia. There are still flying reptiles (pteranodontids and relatives) and fully marine reptiles (mosasaurs, plesiosaur-adjacent forms) in the oceans and skies. Most of the "standard" megafauna, however, sits in the Pliocene-to-Pleistocene range — mammoths, giant ground sloths, that sort of company.
Where it gets deliberately divergent from Earth: no true equines exist. No horses, no donkeys, no zebras. In the Europe-analogue regions, the ecological niche has been filled by derived rhinoceros relatives — some of these have convergently evolved a more horse-like body plan, and yes, one lineage has a single prominent nasal/frontal horn, so "unicorns" here are essentially rhino-horse cousins rather than magical creatures. Tapir-derived ungulates fill similar roles elsewhere. South American native ungulates — your litopterns, notoungulates — never went extinct here and are still doing their thing. All bovines are present and accounted for. The fauna is meant to feel genuinely alien to someone expecting standard fantasy wildlife, but grounded in real evolutionary logic.
The Sapient Species — and the Problem I Keep Running Into
This is where I'd really love input. I have humans, and then a range of non-human peoples. The "classic" fantasy types are present — elves, dwarves, orcs — but I'm trying to resist treating every sapient species as just a reskinned human with a cultural aesthetic stapled on.
The species I'm most uncertain about how to approach are the ones with significant non-human physiologies:
- Minotaurs, Satyrs/Fauns — bovine and cervid/caprine people respectively. These aren't just "buff human with horns" — I want their physicality to actually mean something. A minotaur's digestive system, sensory range, the social role of horn display — these should shape their cultures in ways you couldn't just hand to a human character.
- Merfolk — fully aquatic or amphibious? What does sapience look like when your entire material culture has to work underwater? Tool use, communication, concept of territory — all of this changes.
- Cynocephalians — my working name for the dog-folk cluster of peoples. There are at least three distinct groups here: Dog Kobolds (smaller, pack-bonded, den-dwelling, probably eusocial-adjacent), Dogmen (larger, more varied, filling a broad ecological/cultural range), and a third group colloquially called "Werewolves" — I'm not going for the horror monster angle, more like a people whose morphology and behaviour pattern reads as threatening to outsiders. High-scent, nocturnal or crepuscular, potentially with a very different relationship to hierarchy and territory than other sapients.
My big question with all of these: how do you build a sapient species that feels like a species rather than a demographic? I want their non-human traits to affect epistemology, not just aesthetics — how they understand time, kinship, property, death. But I also don't want to fall into the trap of making them so alien they can't function as characters in a story.
The Core Question
How do you balance all of this — prehistoric holdovers alongside modern fauna, no horses but rhino-horses, South American ungulates living alongside mammoths, and a sapient ecosystem where some people have rumens and some navigate by scent-memory — without it feeling like a random grab-bag? Is there a way to give it internal coherence that goes beyond "the world is just bigger and weirder"? Has anyone done something similar they'd point me toward?