https://api.inaturalist.org/v1/taxa?taxon_id=45933&rank=species&per_page=200&page=1
https://api.inaturalist.org/v1/taxa?taxon_id=45933&rank=species&per_page=200&page=2
Those two pages together return all 286 species in Sciuridae in the iNat taxonomy.
More discussion/info here: https://forum.inaturalist.org/t/is-there-a-tool-code-snippet-that-allows-downloading-of-taxonomy-data-from-the-site/14268