Osteno: Jurassic Preservation
to the Cellular Level
Carol M. Tang
JURASSIC DEPOSITS NEAR OSTENO IN NORTHERN ITALY HAVE yielded a beautifully preserved marine fauna that contains not only fish, sharks, and crustaceans, but also polychaetes, nematodes, and one of the few enteropneusts (acorn worms) in the fossil record. Although nonmarine fossils are not a dominant part of the assemblage, terrestrial plants and the first Italian dinosaur have also been recovered from this deposit. Fossils are fairly sparse in this stagnation Lagerstätte, but the yield is well worth the search as the spectacular preservation has allowed for soft-part preservation even at the cellular level. The presence of details—ranging from cephalopod musculature patterns to polychaete coloration to arthropod stomach contents—provides paleobiological and paleoecological information that is extremely rare in the fossil record. The Osteno deposit was discovered in 1964, and the first fossils were described in 1967 by Giovanni Pinna. The first information on these soft-body organisms was published by Arduini, Pinna, and Teruzzi in 1980, and these fossils have been systematically collected, beginning in 1980, by the Natural History Museum in Milan. Surprisingly, the extraordinary Osteno fauna and mode of soft-body preservation have not achieved the worldwide fame that many other Jurassic Lagerstätten have enjoyed.
The Osteno Lagerstätte is part of the Lombardische Kieselkalk Formation, also known as the Moltrasio Limestone Formation. The deposit is