One of the easiest ways to obtain Deinonychus eggs early-on in Fjörder is to tame a Snow Owl. R - Snow Owls can be found near the redwoods and are an easy tame, even at a higher level. With their swoop, you can glide down and get the aggro of nearby rexes and lead them to the deinonychus, or lead the deinonychus to stegos / trikes if there isn't any rexes nearby. If you are too low of a level for the Snow Owl saddle, Pterandons are advised. I would personally avoid any conflict between you and the actual Deinonychus. It is easier to deal with a rex than the cliff chickens. Before I forget, they can be found all around the large castle located near the grasslands. The area is very dangerous and I would stick to the air. The best mounts for the job are Griffins or Desmodus, but I would rather get them early with a Snow Owl or Pteranodon.