John Nudds Tuesday evening talk

The Solnhofen Limestone

This has been worked since Roman times - they used tiles as roof slabs and, internally, for floors, tiles, mosaics etc. It takes a good polish. M&S use some!

It is worked entirely by hand and made up of two main types, Flinz, which is thicker beds, porcellanous, 98% CaCO3, and Fäule which is land derived clay and mud in thinner beds, and about 90 - 95% CaCO3.

The Flinz is used for tiling slabs etc but the Fäule discards go to cement production.

Fossils are found on the underside of Flinz layers with the main fossil on the overlying Flinz and the counterpart in the underlying Fäule. Any found completely in Faule are hard to extract and break easily.

The cause of the cyclicity of deposition is uncertain but over 95 m was deposited in 0.5 Ma in the Hybonoticeras hybonotum ammonite zone which is at the base of the Tithonian.

There are also sponge/microbial mounds of earlier Oxfordian age which we will see in the Altmuhltal. 

Two useful diagrams below show the palaeogeography of the area, John reproduced these in his talk. 

https://www.researchgate.net/publication/259128394_First_occurrence_of_encrusting_nubeculariids_Foraminifera_on_a_mobile_host_Crustacea_Decapoda_from_the_Upper_Jurassic_Eichstatt_Lagerstatte_Germany_A_new_possible_relation_of_phoresy

Fig. 1. Location of the studied Eichstätt quarry and distribution of the three major lithologies in the area (modified after Munnecke et al., 2008). 

Fig. 2. Solnhofen lagoon and the origin of the Solnhofen Plattenkalk (modified after Barthel, 1990). 

Autochthonous organisms in these lagoons included 

Bony fish: Lepidotes, Gyrodus, Caturus, Leptolepides

Squid

Coprolites lumbricaria (stringy poo, like a goldfish!)

Crinoids, particularly Saccocoma

Ophiuroids - brittle stars

Sea urchins

Starfish

Allochthonous organisms, probable swept in from open sea:

Crustaceans

Cyclereon - a lobster like animal

Mesolimulus

Octocoral gorgonia - sessile, is rare and fragmented

Ichthyosaurs - these are rare in Solnhofen, only 10 - 12 have been found

Plesiosaurs - evidenced by a single tooth!

Crocodiles - are in the Jura Museum but sadly this is currently shut

Cartilaginous fish are represented by sharks and rays

Definitely allochthonous

Dragonflies and other insects - all winged

Pterosaurs such as Rhamnorhyncus and Pterodactyloids

Lizards - there are three Tuatara

Composagnathus (which could be from Kimmeridgian, below the Solnhofen and one had a Bavarisaurus lizard in its stomach

The Solnhofen museum has fossils from the whole area where there were about ten lagoons. There are older coral reefs in the Eastern part (where older dinosaurs were also found) and the lagoons moved west over time as the area became marine. This could have affected Archaeopteryx evolution - they could fly from one island to another and different vegetation on different islands could have led to speciation. Teeth were important for evolution from therapods to fliers.

#9 the "Chicken Wing" shows evidence of flight but unable to flap its wings (muscle attachment evidence)