>>9169261>>9169328Mainframe clearly knew how to make a relatively realistic looking bird, so Silverbolt's weird warping of his model is clearly the result of his skeleton being overridden by animations.
The toy was clearly designed first, and the show model was originally based off of it before being modified after the fact. His 'Condor' wings seem to attach to his back rather than to his shoulders like normal wings, and the way the textures stretch and unnatural way the wings themselves fold suggest they were not intended to hang down the way they do in the show. His upright stance clearly doesn't flow with the way his body is designed, either - the massive amount of weight distribution in the chest suggests he was intended to be leaning forward, as if he was quadrupedal; a close examination of that pic of his CG model shows a massive, unusual bump on either side of his chest that seems to be where they plugged up the holes for his actual forelegs. You can also see that the Griffin ears that are present on the toy were moved down on the show model - the round circles were supposed to be on the sides of his head, not on his throat. This also explains the weirdness of the toy - once the modified model was revealed, the toy (which already existed, as it was supposed to be the basis of the show model, but hadn't been released yet) had to be modified to match - it was likely too late to make a whole new one, so they had to make the transformation work and find an alternate place to stow the extra limbs. They settled for splaying them awkwardly against his wings and standing him upright (ignoring the fact that the toy still has Griffin ears).
Not sure why they decided to make the changes (maybe they wanted to steer away from mythological beast modes, even though Megatron was already a dragon?), but it's clear that he was not intended to be a condor from the start, and the decision to change him must have happened very, very late into production.