I find it interesting and educational to compare the same fauna from different sites with varied types of sedimentation and preservation. Since a lot of you spend your time collecting in the lower Jurassic, I thought I could begin by showing some ammonites from some continental European sites which I have collected. Here are some typical finds which are exactly the same species from the same time as on the Yorkshire coast, but their preservation is quite different.
The first one is Dactylioceras athleticum from a Quarry in Fuegerolles, Normandy, France. The quarry is unfortunately closed now to collectors, but I was lucky enough to visit it before they shut the doors. The preservation, as also with the following Dactylioceras commune is as a somewhat calcified mold. The next one is also Dactylioceras athleticum, but this time from Schnaittach in Bavaria, Germany. You find these ones on farmers' fields in the area in an extremely hard limestone which is not easy to prepare. They have a good separating layer, though, but unfortunately it usually lies beneath the shell, which makes for a lot of hard calcified molds.
Best wishes from the Lake of Constance. Roger.