Wednesday, March 3, 2010

Ancyrocrinus Crinoid

The Ancyrocrinus spinosus? crinoid from the Middle Devonian Period (406-385 million years ago). These crinoids were found in North Vernon Limestone, Beechwood Member. The location is Speed, Indiana (Clark County).

This crinoid was unique in that it had this holdfast anchor or grapple shape that snagged on rocks or other seabed objects. The benefits could be the crinoid is more mobile and less likely to get buried in sea storms.

Classification of this crinoid would be Class: Crinoidea, Order: Cladida, Family: Botryocrinidae (Thanks to the Cochise College Geology page for that info).

The first picture shows a more unique configuration with a double prong on one side of the holdfast.  Usually I find them with four prongs and they about 90 degrees apart.  All of the specimens here were found by my friend Mary Ann.





Here is one I found in 2008 at Speed, Indiana.

Here is another posted in the KYANA Geological Society website with its prongs mostly intact.