We've been having this issue for awhile and we couldn't figure out what was causing it till one of our players was doing some testing and found that when you had a dino in the dragon's grasp and you were too close to the ground when you set down, more often than not the dino would grow extremely large (like the size of the dragon) and then would glitch in the air. There's no way to unglitch it that I've been able to find. It currently has only happened to ankys and frogs. but may have affect other dinos.
We've tried to replicate this with quetzals and argents but we can't come up with the same issue.