[taneq]

There is an ideal size and it’s determined by the size of the island. For a given size of island there’s a maximum size of predators that it can support. You want to be big enough that these predators aren’t much of a threat, but small enough that you can keep your own population size viable.

[simmerup]

There's also the consideration that animals just don't grow as large if they don't get the necessary food.

Like how humans used to be so much shorter in the Middle Ages.