Hard to say, really.  While the original Scheme development was in the late 1970s and the CL standardization effort didn't get going until a few years later, CL's roots are of course much older, and it was strongly influenced by Lisp Machine Lisp which was under development at about the same time as Scheme.  The situation is fuzzy enough that I think the best you can do is to call them roughly contemporaneous, with some cross-fertilization, notably in CL's lexical scoping.

I've never attempted any substantial development in Scheme, but have wondered whether I were missing anything, so Attila's observation is of interest.

-- Scott