Solnhofen: Plattenkalk Preservation
THE UPPER JURASSIC SOLNHOFEN PLATTENKALK (LITH ographic limestone), named after a small village in southern Germany, is probably the world's most famous Lagerstätte. A wealth of exquisitely preserved fossils have been unearthed over the years, with many of them showing soft-part preservation, mainly in the form of imprints. This is also the place where the oldest known bird, Archaeopteryx, has been found (Hecht et al. 1985; Padian and Chiappe 1998). The most common fossils, however, include floating crinoids, ammonites, crustaceans, and fish, as well as occasional jellyfish, squid, insects, and fully articulated reptile skeletons.
The Solnhofen Plattenkalk, an up to 90 m thick succession of almost pure, thinly bedded limestone intercalated with shaley layers, was deposited in a restricted area in northwestern Bavaria, Germany, extending approximately 80 km in an east–west direction and only about 30 km in a north–south direction (Figure 18.1). Deposition of the Plattenkalk occurred in only a series of small basins surrounded by bioherms and reefs, probably under hypersaline and oxygen-depleted bottom-water conditions (Viohl 1985, 1996; Barthel, Swinburne, and Conway Morris 1990; Wellnhofer 1990). The Solnhofen Plattenkalk is, therefore, a classic conservation Lagerstätte that is a stagnation deposit, although a certain amount of obrution and bacterial sealing may have been crucial for the splendid preservation of the fossils (Seilacher, Reif, and Westphal 1985).
The Solnhofen Plattenkalk has a long history of exploitation. Some carvings on Solnhofen limestone date back to the late Stone Age, and since Roman times the Plattenkalk has been extensively used as building material. In 1793, Alois Senefelder invented lithography (Barthel 1978),