Revealed Monsters, so far...
Here is a list of the monsters revealed from the trailer.
A T-Rex like brute that seems to have a keen sense of smell and some type of set of small wings or flare to scare off other predators. During a closed door demo at E3, it was said that this monster can be tracked by the drool it leaves behind.
King of the Skys, the series veteran returns to Monster Hunter World!
The smaller type of the Great Jagras.
The scavenger flying serpents.
During the trailer, we see these could be some kind of transportation?!