Most probably that the world was much warmer during this time period. Regardless of waters high specific heat, most likely if marine specimens from a wide range of areas across the planet were to show the same results, it proves it isn’t a specific area rather that the entire climate was much warmer.
Any herbivores would have thrived if left alive. same with the smaller predators like foxes or owls. populations shoot up. increase in inbreeding if the islands are isolated and eventually disease catches up with them
