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Solnhofen Limestone
by Jessica Hoffman
Physical Geology
Fall 2007
         

Solnhofen Limestone  
 

          The Solnhofen Limestone is found north of Munich in Bavaria, Germany.

 

Above photo credited to: http://www.ucmp.berkeley.edu/mesozoic/jurassic/solnhofen.html

 

          The limestone dates back to the Jurassic Era. The area that the limestone is found in covers a 100km by 25km area and in some spots the limestone is deeper then 150m.

 

          The limestone is used for many different things such as floor tiles and roof tiles. When fossils are found they are sold to scientists and tourists.

 

Above photo credited to:
http://www.dkimages.com/discover/Home/Science/Earth-Sciences/Palaeontology/Fossils/Invertebrates/Arthropods/Insects/Damselflies-and-Dragonflies/Unidentified-Species/Unidentified-Species-3.html

 

 

          There are both hard and soft beds which alternate from one to the other making it easier to get the hard stuff out which is used more often for the floor tiles and roof tiles. In the harder beds the fossils are found easier. Around the hard beds are the soft beds which make it easy to split the limestone and mine it.
 

          Fossils are often found in the softer beds but since the local quarries are not mining the Solnhofen limestone for the fossils they are discarded.

 

          There are many different terrestrial fauna and marine fossils found in the limestone but the most popular is the dinosaur bird which has a scientific name of Archaeopteryx Lithographica.

 

Features of Archaeopteryx shared with reptiles (diapsids plus turtles) in general but not with other birds

 

  • Long bony tail. Modern birds have fused caudal bones for the attachment of the feathers that form the tail.
  • Digits have claws. Juvenile ostriches have clawed digits.
  • Vertebrae are reptilian in structure and lack the spiny, stemmed appearance of birds.
  • Stomach ribs (gastralia) are present, as in plesiosaurs, crocodilians and dinosaurs.
  • Presence of interdental plates.
  • Carpals in the wrist are unfused with the exception of the third carpal. Birds have fused carpals and metacarpals.
  • Tarsals in the ankle are free with the exception of the fused third tarsal. Birds have fused tarsals.
  • The bones are solid and lack pneumaticity, with the exception of the cervical and anterior vertebrae.
  • The sternum was not bony or keeled, leaving no attachment point for flight muscles. Birds have a bony sternum, but some birds lack a keel.
  • The coracoid is rounded; in birds it is much elongated.
Features of Archaeopteryx shared with birds, but not with dinosaurs or other reptiles
  • On each foot the first digit extends backward (a semi-reflexed hallux). This may have been reported in some dinosaurs.
  • The quadrate bone articulates with the braincase. This may be a general amniote condition.
  • Fused clavicles form the furcula. This has also been reported in some theropods.
  • The "wings" have fully formed, fully modern flight feathers (the main shaft is off-center to the windward side), with barbs and barbules that maintain each feather's shape.
  • Palatine structure is similar to that of thecodonts and crocodiles; distinctively avian.
  • Lack of coronoid bone.
  • Digits 2,3,4 in the forelimb. Until rumored recent revisions, dinosaurs have digits 1,2,3.
Features unique to Archaeopteryx
  • The teeth of Archaeopteryx are widely spaced, conical, without serrations.
  • The prearticular rostral blade of the mandible is unique.
  • The pterygoid bone is distinct in its shape and its articulation with the quadrate.
  • The quadrate bone is long in proportion to skull size.
  • Presence of a prearticular rostral blade.

 

Above chart credited to: http://www.grisda.org/georpts/3001.htm

 

          Most of the Saccocoma found in the limestone have their arms curled up and were preserved that way where as some of the Saccocoma have their arms open.

 

          Some specimens died a quick death. There has been evidence of this found such as some fish have been found that were in the process of eating and swallowing another one. Some Pterosaurs have been found with stomach contents. There have also been half eaten fish found in the limestone.

 

Above photo credited to: http://www.geo.ucalgary.ca/~macrae/t_origins/archaeopteryx/ 

 

Works sited:

www.ucmp.berkeley.edu/mesozoic/jurassic/solnhofen.html

en.wikipedia.org/wiki/Solnhofen_limestone

www.grisda.org/georpts/3001.htm

www.palaeo.gly.bris.ac.uk/Palaeofiles/Lagerstatten/solnhofen/index.html