The rocks around the limestone quarry at Solnhofen, Bavaria, consist of fossilized reefs. It seems that during the Upper Jurassic this region was covered by lagoons, in which limy sediments slowly accumulated to form very fine-grained limestones. This slow accumulation permitted the remarkable preservation of fossils — even internal organs and soft-bodied creatures are preserved in exquisite detail. The most famous specimen to come from Solnhofen was one of the few complete examples of Archaeopteryx, the earliest known flying vertebrate. (M 23351) _ _.