Well, considering that the animation for most of the beast modes were notorious for being simplistic and inaccurate, I'd instantly lean away from the Deinonychus as being the correct version of a beast mode. The "Velociraptors" of Jurassic Park no doubt inspired the animators for Dinobot. (And they weren't real 'Raptors, either. The skeletal structure of their cranium was inaccurate, and actually was a rather good match to Deinonychus.) The images to compare really aren't that great of angles, but I didn't have that much time to really find the shots I was looking for.
Here's Dinobot. Look more towards his snout, and remember that the angle sucks, because then you can't see a true profile. Use a touch of imagination:
Here's the original Jurassic Park "Velociraptor." Note the head shape. The second JP movie came out after Season One of Beast Wars was out, therefore trying to make amends with the inaccurate skull shape. But this would have been what the animators at Mainframe would have seen at the time.
This is an excavated Velociraptor mongoliensis skull:
And V. mongoliensis reconstructed:
To compare with the Deinonychus skull:
And I know all this crap because I'm a geek. Utter and complete geek. Who had been obsessed with 'Raptors since I was in middle school and had been watching BW every morning before school when it was on the reruns. Yeah. THAT kinda geek. I even did my eighth grade science report upon the inaccuracies and theories about the blasted creatures.
... *hugs Dinobot* poor, poor mech with such confusing species (read: identity) problems ......