A clever guy:Mitch GrossNYC DP
expaines a lot here:
A lens mount has nothing specifically to do with a film format, but here's some basic info. I swear I wrote this all up before, but perhaps it wasn't on the CML. I'm going to skip some ancient and obscure mounts.
Arriflex
Arri started with their standard mount, which was a ring with a small tab inside. This was common on the 35mm Arri 2c (and variants) and the 16mm Arri S. Later they developed the Arri Bayonet mount, which was the same sized ring with two outer "wings" that locked the alignment of the lens and provided a stronger mount. Standard mount lenses could be used in Bayonet mounts but not the reverse. This mount was common on later Arri 2c, S, M, 16BL, SR 1, SR 2, 35BL1, 35BL2, early 35BL3, 3c and early 3 cameras. This very popular mount was replaced by the Arri PL (Positive Lock) mount, which features a large four-point flange on the lens and a clamping disk on the camera for a very strong and stable mount. With adapters, Arri Standard and Bayonet lenses can be used. This is the most popular mount available today, standard on such cameras as later Arri BL3, BL4, BL4s, 535a, 535b, later Arri 3 models, 435, Moviecam Super, Compact, SL, later Aaton 16 & 35 cameras, ArriCam ST and LT models.
C-mount
A threaded, screw-in lens mount of a rather small size. Generally only good for small primes and lightweight zooms and used primarily for small 16mm and industrial video applications. Cameras include Bolex, Beaulieu, secondary mounts on the Eclair NPR and ACL, and numerous industrial video cameras. The C-mount has a very short depth, which means that adapters mounts which put the lens further out can be made for numerous types. I've seen adapters for C-mount cameras to take all the Arri mounts, plus just about any still camera or other cine or video lens mount one can think of. There's still the issue of the fairly weak thread design, but some adapters get permanently installed and hard mounted to the frame of the camera body.
Eclair
Eclair developed the CA-1 mount for their cameras when introduced in the late fifties. This mount uses a two-prong flange like the PL but is much smaller, about the size of the Arri Bayonet. This mount was available for the 35/16 Cameflex (CM-3), some high speed cameras and the 16mm NPR and ACL. The ACL also offered adapters for other mounts including Nikon and the smaller Arriflex mounts. Today these cameras can also be retrofitted to PL mounts.
Aaton
The Aaton mount is a three-prong flange that is about the same size as the Arri Bayonet mount, but it's great advantage it it's relatively shallow depth. This allows it to accept various adapters for Nikon, Leica, and the smaller Arri mounts. This mount was standard on the Aaton LTR-7, LTR-54, and early XTR models, and was an option (instead of PL) with the XTR-plus and XTR-prod. The Aaton mount is almost identical to the Cinema Products mount (CP-16 and CP-GSMO cameras) and with slight modification any CP camera can accept Aaton mount lenses.
There are other mounts out there such as BNCR, Panavision, plus the standard (and not so standard) video lens mounts but I think this answers the spirit of your question.