Back on Typophile, quite a while back I started a thread to the effect that many type designs these days seemed to belong to a particular novel kind of slab-serif.
It might be monoline, or slightly stressed. Often, the outlines seem to take inspiration from Melior or Microgramma.
In that thread, I mentioned FF Olsen as possibly the first representative of this kind of typeface. But I've now found some earlier ones, dating back to 1990. As well, one particular example that catches my eye regularly as I take the bus downtown has been pinned down, thanks to MyFonts' identification system: Calypso E Medium was used by a restaurant called the "Central Social Hall" in Edmonton for its logo.
It's just interesting how a style of type that in a previous decade was not in evidence can suddenly become hugely popular.
I don't think any of the slabs from the 1970s or earlier have enough resemblance to FF Olsen to draw a line. There are some superelliptical/squircular designs in the Photo Lettering catalog but everything was still very Clarendonian. City Bold has sort-of-open shapes but that connection seems unlikely to me.
I don't see much of a resemblance between pre-1990's slab-serifs and 1990's slab-serifs. Even though Frutiger lacks serifs, I think it has more in common with those 1990's types. If you took Frutiger and stuck slabs on it, I think it would look a bit like a 1990's slab=serif typeface. I went through all my old catalogs looking at slabs and everything's pretty much a Clarendon sort of deal with closed shapes. Nothing you could trace to that 90's trend. Even the squarish slab-serifs look like squarish Clarendon or classic typewriter.
Maybe I shouldn't dismiss City Bold as there was a revival of it in postmodern design that went from the 1980's through the early 1990's.
But are there earlier monolinear slab serifs with a dynamic skeleton, prior to PNM Caecilia/Officina Serif?