Solnhofen Ammonite Aptychus #5
1 in stock
- Solnhofen Limestone
- Eichsatt, West GermanyAptychi seem to have most often existed as bilaterally-symmetrical pairs, and were first described (incorrectly) as being the valves of bivalve mollusks. Aptychi are now considered to be either: (1) a two-valved closing hatch on the shells of extinct ammonites; or (2) a double-plate jaw-piece similar to that of some modern cephalopods. Set near to or against the shell’s terminal opening (the living chamber), the aptychi usually consisted of two identical but mirror image valves. Some authors consider the aptychus to be a jaw apparatus (mandibles), while others believe them to be paired opercula. If the latter is the case, then aptychi may have had a function similar to the head shield of modern nautiluses.
The celebrated Solnhofen limestone is among the most important fossil deposits because of its astonishing diversity of organisms, many exquisitely preserved. Marine and terrestrial creatures and plants, buried 150 million years ago in soft lagoonal muds, provide a unique glimpse into the true diversity of Jurassic life. Articulated skeletons are preserved, as well as some soft bodied animals that otherwise would be too delicate to survive fossilization. Among the highlights are superbly preserved jellyfish, crustaceans, squid, fish and flying reptiles. Perhaps most important of all is Archaeopteryx– the celebrated “missing link” which has the skeleton of a dinosaur but is covered in feathers, revealing a crucial evolutionary transition between the reptiles and birds. Solnhofen opens a window into a vanished world, and reveals the unexpected richness of a land and sea teeming with life. Many specimens from the Solnhofen Limestone have been cracked during the excavation process but all have been expertly repaired and restored and do not detract from the beauty of the specimens. When most specimens are found they are found when the limestone is split. As a result, some of the finer details can be missing. When that occurs the preparators most often use a tint and brush those details back onto the specimen to make it complete. VERY FEW specimens have not had this done.. those specimens that are 100% complete and natural demand premium prices!
The Solnhofen Plattenkalk, or Solnhofen limestone, is a Jurassic Konservat-Lagerstätte that preserves a rare assemblage of fossilized organisms, including highly detailed imprints of soft bodied organisms such as sea jellies. The most familiar fossils of the Solnhofen Plattenkalk include the early feathered theropod dinosaur Archaeopteryx preserved in such detail that they are among the most famous and most beautiful fossils in the world. The Solnhofen beds lie in the German state of Bavaria (Bayern), halfway between Nuremberg (Nürnberg) and Munich (München) and were originally quarried as a source of Lithographic limestone.
During the Late Jurassic, this area was an archipelago at the edge of the Tethys Sea. This included placid lagoons that had limited access to the open sea and where salinity rose high enough that the resulting brine could not support life. Since the lowest water was devoid of oxygen, many ordinary scavengers were absent. Any organism that fell, drifted, or was washed into the lagoons from the ocean or the land became buried in soft carbonate mud. Thus, many delicate creatures avoided consumption by scavengers or being torn apart by currents. The wings of dragonflies, the imprints of stray feathers, and terrestrial plants that washed into the lagoons were all preserved. The fossils are not numerous, but some of them are spectacular, and their range gives a comprehensive picture of a local Jurassic ecosystem. At times, the lagoons almost dried out, exposing sticky carbonate muds that trapped insects and a few small dinosaurs. Over 600 species have been identified, including twenty-nine kinds of pterosaur ranging from the size of a sparrow to 1.2 m (4 ft) in length. The fine-grained texture of the mud silt forming the limestone from the Solnhofen area (which is composed mainly of the towns of Solnhofen and Eichstätt is ideal for making lithographic plates, and extensive quarrying in the 19th century revealed many fossil finds, as commemorated in the name Archaeopteryx lithographica, all the specimens of which come from these deposits.