In the temporal war someone must have cleaned up any evidence of the sauropods

Star trek is fictional

I actually think the episode itself is quite good. The framing of the episode, the part where the dinos left earth and ended up in the delta quadrant, is just awful and follows a long terrible tradition of Trek not even having a cursory understanding of evolution. But the storytelling is good. Learning about both the Voth and Voyager from the perspective of Voth scientists is good. Having them be much more advanced than Voyager and then actually showing that is a nice change of pace. The moralizing part is good too: respecting the journey for scientific truth even is important, though the message is a little muddled because the science of the episode is so hilariously wrong. A Chakotay heavy plot without any sky spirits is nice. The Voth were relatively good looking aliens for the time.

I think if it were rewritten just a little bit it’d be a top 10 Voyager episode.

You’re not wrong, but I didn’t find it that hard to believe in the universe. Those dinoids(?) had been advanced even back then. Oh how that episode would have been butchered had it been made today, though.

If their technology was advanced enough, it may have been biodegradable which would explain the lack of evidence.

But also TNG explained the origin of humans, vulcans, Klingons and romulans in episode “The Chase” years before Voyager started, which counters the theory proposed in it.

It is an exceptionally bad episode. If not for Threshold glossing over the massive plot hole of not using warp 10 to get home sooner (with the crew tucked into the pattern buffer and The Doctor informed of how to manage the ship), this would take the cake.