Complex sentence: Clive is still adamant that the creature should be killed, but Elsa convinces him that it is too late, and points out that, since the hybrid is slowly dying anyway, they should take advantage of this unique opportunity to observe its complete life cycle.
Split into simpler sentences: Clive is still adamant that the creature should be killed, but Elsa convinces him that it is too late. She points out that since the hybrid will be dead soon anyway, they should take advantage of this unique opportunity to observe its complete life cycle.