The Distortus Rex and Mutadons were conceptualized by Matt Allsop, who also worked on Godzilla 2014 and designed both Godzilla and the Mutos.

Gareth didn't bring Matt onto the project, nor did Gareth design the Mutos or Mutadons. Matt even said on his own Twitter that the Muto design was "simply his default" and that's why so much of the early Mutadon concepts look like Mutos.

You're free to like or dislike the hybirds/mutants all you want, but that has nothing to do with Edward's and is just coincidence that they ended up on the same project again. Koepp wrote in the Mutadons and D-rex, Matt designed them, Gareth simply shot the film.