Solnhofenin

Solnhofenin is a term encountered in some historical and regional writings referring to the fossil-bearing rocks of the Solnhofen area, most notably the fine-grained limestone formations that have yielded numerous exceptionally preserved fossils. In current geological usage, the rocks are generally called Solnhofen limestone or lithographic limestone, and solnhofenin is not a widely recognized mineral or formal stratigraphic term.

Geographically, the Solnhofen area lies in the Franconian Jura of Bavaria, southern Germany. The rocks date to the Late Jurassic, commonly placed in the Kimmeridgian to Tithonian stages, about 152 to 150 million years ago. The lithology is characterized by very fine-grained, laminated limestone with low sedimentation rates, often forming thin beds that are suitable for quarrying as lithographic stone.

Depositional conditions were a shallow, restricted marine environment, such as a tropical lagoon with limited water exchange and episodic hypersalinity. Such settings promoted anoxic or near-anoxic bottom waters that slowed decay and enhanced the preservation of delicate fossils, including impressions of soft tissues in some specimens.

The fossil record from Solnhofen is renowned for its exceptional Lagerstätte quality, contributing key insights into Jurassic marine life and, notably, the early evolution of birds, with Archaeopteryx lithographica among its most famous discoveries. The site also preserves a diverse assemblage of crustaceans, mollusks, echinoderms, and fishes.

Today, the term solnhofenin is rarely used in formal taxonomy or geology; the established name for the rocks is Solnhofen limestone, and references typically point to this formation when discussing the locality and its paleontological significance.