Some strange Sonic CD sprites

[MCTravisYT]

I've wondered about this for months at this point and never came to a clear conclusion about these sprites. I'm specifically talking about the angled rotation sprites.

I've seen these show up quite a few times in sprite sheets, however, I've never seen this in-game. It's actually not even used in the game, rather it snaps directly to a back view.

I can't seem to find the "source" for this sprite anywhere, it doesn't seem to exist in the final game. Although, they are present (unused of course) in the 0.02 prototype. They are not present in the 2011 remake.
What I find odd about these sprites, due to them not being found in any prototype before 0.02's release, is that a 2016 spritesheet features these sprites.
Where do they come from? Are there any other places they could've been found in CD?

 

[MarkeyJester]

Sounds to me like they were designed for that 3D loop (I know, let's just... give the team the benefit of the doubt, it's meant to be a loop...), but never got programmed in. I suspect the remake didn't have them purely on the basis of auto-optimisation? Ya know, removing non-used frames from resource. So I strongly suspect it won't be used anywhere else.

Sonic's head angle seems to match the running angle for that 3D loop, so I donno about anyone else, but I'm certainly satisfied it was meant for that loop for rolling. Nice find!

 

[MCTravisYT]

So it turns out the PC version of Sonic CD has these sprites. That solves the mystery. (thanks to RetroGamingisAwesome on Discord for the sheet)

Spoiler: Spritesheet