Submitted by: David Thompson
Taxon: Grammysia sylvaniensis, Grammysia nodocostata
Submit date: 2008-05-13
Location (approximate): Milan, Washtenaw, MI
Stratigraphy: Silica Formation
Age: Erian (Middle Devonian)
Submitter notes: This series shows two species of Pelecypods from the Silica formation from several angles to show their structure but this is not too exciting to view. The Silica bivalves generally are casts or Steinkerns with little shell other then thin phosphatic layers and as such are overlooked. Here are two similar species distinguished mostly by size. The larger is nodocostata and the smaller is sylvaniensis. The smaller is 2' long by 1 1/4' wide (5 X 3 cm). The larger is 2 1/4' long by 2' wide by 1 1/2' high (5.5 X 5 x 3.5 cm).