Solnhofen

Every known specimen of Archaeopteryx came out of this rock. All of them. The species name, Archaeopteryx lithographica, records why: the stone was quarried for lithographic plates, and the same fineness of grain that took an image also took the imprint of a feather.

The Late Jurassic sea here, about 155 million years ago, was warm, shallow and studded with islands, and reefs of sponge and coral divided it into lagoons. Those lagoons were cut off from the open ocean and from runoff, so salinity climbed and the bottom water went anoxic or outright toxic. Almost nothing could live down there, which meant almost nothing could eat what arrived. Anything that fell in from the land, drifted in from the sea, or was washed in by a storm settled into soft carbonate mud with no scavenger to break it up and no current to scatter it. Dragonfly wings, stray feathers and land plants all survived. When the lagoons nearly dried out, sticky exposed mud trapped insects and a few small dinosaurs.

Solnhofen fossils are not abundant. They are simply extraordinary when they come. More than 600 species have been identified, including twenty-nine kinds of pterosaur from sparrow-sized up to 1.2 metres. The nearest modern parallel anyone has suggested is the Orca Basin in the northern Gulf of Mexico, although that sits far deeper than these lagoons did.

The beds run through Bavaria between Nuremberg and Munich, and they have been worked since the Stone Age for roof and floor tiles, long before anyone quarried them for lithography. The International Union of Geological Sciences named the Solnhofen and Eichstatt Archaeopteryx serial site to its list of 100 geological heritage sites worldwide.

You can look for your own. The museum in Solnhofen sits beside a hobby quarry, and there are working quarries nearby where fossil hunting is part of the visit. The Jura Museum at Eichstatt holds the deep collection, marine reptiles and pterosaurs included, and one Archaeopteryx.