It looks like we might be getting it soon. There is Audio of the dinosaur and of Cabot Finch talking about it, as well as the name in the new Carnivore pack files. Sounds pretty promising.
I've kind of wondered if it's more of an anniversary dinosaur, they're getting it finished early due to the entire thing of an update to add the stego skin after the challenge. If they got it done early, having it ready to go might be a better option for it.I think that if they're going to release a Euplocephalus it will probably be released for easter or around there.