So are we seeing greater speciation today with larger distinctions between species?
Not much — there’s no speciation going on today, as far as has been observed. In the fossil record there’s a broad diversity of critter types, same as now, with unknown numbers not preserved, or poorly represented (no complete type specimen). This suggests that there’s not much difference in the sheer number and diversity now as there ever has been — but it’s apparent that whole taxa vanished at the various paleontological boundaries.