While at the Battlefield 4 EA event in Los Angeles, YouTuber Drift0r asked a member of an EA team who was there if there were going to be dinosaurs in BF4. This happened after one of their play sessions where he and the other YouTubers were put in a conference room and asked by an EA marketing team to comment on the state of the game. After Drift0r asked this question, one particular EA guy became frustrated and said that he was not allowed to talk about dinosaurs and wanted to move on. The group repeatedly asked the guy about the dinosaurs until the EA guy let slip that after the Los Angeles event, he had to write a massive report on dinosaur popularity and hand it in to his boss. He also mentioned that everyone at EA and DICE are very much aware of the demand for a dinosaur mode and that he could not confirm or deny the mode's existence.
http://www.youtube.com/watch?v=JXz9C-nGWbg
Drift0r finishes the video by saying that because EA is aware of people's desire to see dinosaurs in Battlefield, we should continue to let DICE and EA know that we actually want this to be in the game and not just be a joke on the Internet.