Crania Silurian Brachiopod Holdfast

This Eucalyptocrinus crassus crinoid calyx bears the remnants of a Crania sp. brachiopod.  These brachopods existed in the Middle Silurian Period and their fossils can found in the Waldron Shale of Indiana. These brachiopods tended to attach to dead crinoids and brachiopods.

The next picture is an illustration of four holdfasts of the Crania siluriana brachiopod. The illustration shown was drawn by J.C. McConnell and can be found on Plate 21, Figure 6 of the Indiana Department of Geology and Natural History (Eleventh Annual Report) John Collett, State Geologist, 1881.

Last picture is of the first fossil shown but showing the attached matrix.

Gyroceras elrodi Cephalopod

The illustration shown was drawn by J.C. McConnell and can be found on Plate 37 of the Indiana Department of Geology and Natural History (Eleventh Annual Report) John Collett, State Geologist, 1881. The fossil is identified as a Gyroceras elrodi found in the Silurian Waldron Shale of Indiana.

The next image is of Plate 38 Figure 4 showing a close up of the shell imprint. Described as "Portion of surface showing revolving and transverse lines."

Placenticeras meeki Ammonite

This ammonite fossil is quite ornate with fractal like patterns representing sutures. The ammonite is known as the Placenticeras meeki found in the Pierre Shale Formation of the Badlands of South Dakota, USA. Unfortunately, I did not image it with a ruler but if I recall correctly it was over 10 cm wide.  This animal swam in the Upper Cretaceous (70 million years ago) seas.

The next picture is of a much higher resolution if you want a zoomed in view of the patterns.  The last picture shows the iridescent covering on the other side of the fossil.  Thanks to Mark Palatas for allowing this to be photographed.

Here is a link to flickr showing a very similar one at the South Dakota School of Mines Museum: CLICK HERE