The crista which would have supported the secondary tympanic membrane in C. saharicus was either absent, or not preserved.

The secondary tympanic membrane (or round window membrane) covers the round window, sealing off one of two openings into the inner ear.

It is placed at the bottom of a funnel-shaped depression (the round window niche) and, in the macerated bone, opens into the cochlea of the internal ear; in the fresh state it is closed by a membrane, the secondary tympanic membrane or round window membrane, which is a complex saddle point shape.