Why no animal life ?

I've been wondering this ever since trailer two launched.What exactly does no animal life mean for Paradise?On one hand i'd almost say this could support that Paradise has terraformed by the black goo,but I'm not so certain.In the Fire and Stone series,we saw the black goo turn what was a barren moon into...well a paradise(sorta.)It created lifeforms,water,plant life etc.So if it's a similar case with Paradise,then why no animals?Another idea is that David turned them all into test subjects,but that's also hard to believe.That would be a lot of animals.We also have images of what appears to be a planet wide extinction event,complete with charred remains of an unidentified species.Covenant the animals have suffered from this too?One thing we know is life exist everywhere,in the water,in the soil.Paradise also has a lot of greenery to be seen,trees,plants,bushes etc,all of which provides oxygen to the world.I would think animals have to be somewhere.After all,yhey have their part to play in the progress of nature,but where did they go?This world seems to be thriving,is that possible without animal life?What do you guys think?