Hello Kili
1. Dinosaurs may have terrorized other creatures during their time on Earth, unless now it has emerged that some species had a taste for the flesh of their own kind.
— i.e. unless now new research has emerged to show that they wouldn't have terrorized other creatures, because they were too busy terrorizing their own kind. Possible.
2. Dinosaurs may have terrorized other creatures during their time on Earth, whether now it has emerged that some species had a taste for the flesh of their own kind.
— only possible if you say "whether or not it has now emerged", i.e. it's of no importance whether they were also cannibals.
3. Dinosaurs may have terrorized other creatures during their time on Earth, because now it has emerged that some species had a taste for the flesh of their own kind.
— possible if the "other creatures" were also members of the cannibal species.
4. Dinosaurs may have terrorized other creatures during their time on Earth, even if now it has emerged that some species had a taste for the flesh of their own kind.
— possible, as the opposite of #3: despite the fact that some species were cannibals, they weren't exclusively cannibals; thus they terrorized other species.
5. Dinosaurs may have terrorized other creatures during their time on Earth, so that now it has emerged that some species had a taste for the flesh of their own kind.
— not possible: having a taste for the flesh of their own kind can't be a consequence of terrorizing other creatures. It should be vice versa.
But like CJ, I'd prefer "but".
MrP