Wednesday, July 23, 2008

Tentaculites scalariformis

Phylum Mollusca and the class is Gastropoda making this creature a small snail.

Its distinctive shell makes it look sort of like a very small cephalopod.

I think this creature is Tentaculites scalariformis.

In the "North American Index Fossils Invertebrates Volume II" by Amadeus W. Grabau and Hervey Woodburn Shimer from 1910 on page 10 describes Tentaculites as:
"Shell straight or slightly curved, elongate, tapering, conical, with circular cross section and terminating posteriorly either acutely or in a bulb. Surface marked by strong tranverse rings which are closely arranged near the apex and more distant and stronger near the mouth. Fine transverse and rarely longitudinal striae are present. Apical portion often filled with calcareous matter or divided off by transverse septa."

It goes on to say creature existed in the Ordovician to Devonian periods with it being very abundant in the Silurian and Devonian periods.

The book describes T. scalariformis (Hall) as:
"Differs from T.bellulus in the more obtuse annulations of the distal portion, with narrower interspaces, and in the more rapidly narrowing apical portion. Onondaga of New York, Ohio and Indiana."

It is also described in the Indiana Department of Geology and Natural Resources Twenty-Fifth Annual Report issued in 1900 on page 736.