Sunday, December 23, 2012

Graphoceras concavum from Geisingen, Germany

A friend of mine, Roger, from Germany was in Canada visiting some of his family recently and I was able to meet up with him and do some trading. He primarily collects from his local Mesozoic exposures in southern and central Germany. I swapped some Trilobites with him and in return he gave me some Ammonites that he'd personally collected and prepped. The specimen below is a Graphoceras concavum ammonite. I like that you can still see some of the surface decoration, in the form of gentle waves, along with some of the suture pattern of the internal chambers.

Graphoceras concavum is the index fossil for the Concavum Zone within rocks that are dated to the Upper Aalenian stage of the Middle Jurassic within Europe. Roger found this specimen in the "Geisingen-Oolith" at the clay pit in Geisingen, Germany. My thanks to Roger for giving me this wonderful specimen!

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