this is a sentence from GRE:
Some paleontologists debate whether the diversity of species has increased since the Cambrian period, or whether imperfections in the fossil record only suggest greater diversity today, while in actuality there has been either stasis or decreased diversity.
I don't exactly understand the latter part of the sentence: specifically, (1) what does "only suggest" mean here? I took it to mean that "the imperfection perhaps purely suggests a more diverse world today." But under this understanding, the second whether would be redundant with the first whether, because both would be talking about the diversity is increasing. Thus, I was very confused when I interpreted it this way. After checking dictionaries and public resources, I still couldn't figure out how to make sense of the sentence.
(2) I have huge trouble in understanding what this part is saying: "Or whether imperfections in the fossil record only suggest greater diversity today, while in actuality there has been either stasis or decreased diversity." If a greater species diversity is suggested, then how come such a greater number could possibly be turned out to be a stasis or decreased diversity?
Any sharing would be greatly appreciated.