A Little Speculation

i suspect there trying to keep a lot of them either secret or there just cameos for a split second of footage

I think that the only ones that'll be in the movie are the ones on the website. The others seen in the holo display are likely in the park, but will not appear as anything more than a name drop (or in spino's case, a skeleton).

On a lot of zoo websites, they don't have the full list of species, so JW could have something like that. Besides, when there's 30 species seen in the Gyrosphere, that explains a lot. On the map, there's Brachiosaurus and (what I presume to be) Lesothosaurus. Also, the Cretaceous Cruise is advertised with 100 species of flora and fauna (well, 94 species of flora is possible, yet HIGHLY unlikely).

Now that we know that there is going to be a JW 2 we may possibly see them there ;)

I've written so many write ups about how this could infact be wrong, But I feel like playing a little bit of devils prada right now.

One word.

Headliners.

You want to display Big attractions to get peoples attentions. And then, Wow them more with how many more species you have. 

INDOMINUS REX - This is an extremely compelling topic! I certainly hope that there are multiple animals in Jurassic World that we have not yet been revealed! I happen to agree with X_PADEN_X's statement: roll out the big guns and then go for overkill! ;)