Yes, we should be seeing species coming into existence by some unbalanced ratio of 4:1 or 10:1 or 100:1. Instead we are hearing that species are dying out at that rate.
If we can document species dying out at 100:1, where is the documented 1 coming into existence?
The Cambrian explosion comes to mind.
Also hugh (sic) increase in mammal species after those pesky dinosaurs died off, leaving empty niches.