In preparation for the first early access release, the Steam store page has been updated to better reflect the state of the game. Nonetheless, for the sake of transparency, below is a list of previous marketing and development media shown that had features that were ultimately postponed.
Flocking/schooling/grouping
Fish still made it into the game (disabled on official server, see last note on this page), but schooling and flocking has been postponed. Foundations have been laid, but it hasn't made into the game yet. Similarly, with limited exceptions, AI generally do not yet behave as coherent groups.
Quetz landing (limited)
The first trailer showed Quetz landing. It still does this, but on predefined locations where the player can't currently reach, and quetz fulfills more of a background role right now.
Ocean/Lake aquatics
The game had some aquatics in the oceans and fish in lakes prior to to the habitat patch. While they get reworked, they're currently not on the the new map. Community servers can however allow spawning fish through the config options available on the server.