@Walter Hinteler,
not familiar with the Wattendorf ls. you say its as much a lagerstatte as is the Solnhofen? Its very fine grained yes? Is it used as graphic limestone also?
I used to buy old hunks of graphic limestones like Solnhofen , because many of these limestones could be split along the fine laminae to expose all sorts of very complete fossils of fish to insects and leaves.
We use the term lagerstatte all over the world, even in the liao Ning Formation of China. Sometimes a Germanic word works best. It beats "very fine grained and thinly laminated clay rich precipitate limestones"
Another favorite is Drackenfeld for little cross check Chatter marks that look like drgons teeth.
The Canadian Burgess Shale is another lagerstatte