Answer:
Formation. When the solar system settled into its current layout about 4.5 billion years ago, Earth formed when gravity pulled swirling gas and dust in to become the third planet from the Sun. Like its fellow terrestrial planets, Earth has a central core, a rocky mantle and a solid crust.
I think thats because small animals have small body that can hide in a safe place. Like example if small animals hide go down to the earth, and the meteorite hit the earth, they will safe down to the ground.
Not like larger animals, they can only hide up he surface and when the meteorites came, they died.
Also some small animals such as cockroaches have ability to adapt to changes.
If, and only if, makes it bi conditional.<span />
