19 February 2010
Fossil crinoid stem
Posted by Callan Bentley
Today, you get a photo of a fossilized crinoid stem, from the Mississippian-aged Lodgepole Limestone of the Bridger Range, north of Bozeman, Montana. A pencil is provided for scale:
Zoomed-in a bit, and cropped. The segments (“columnals”) show up nicely:
Crinoids are echinoderms, the invertebrate phylum which includes sea urchins and sea stars. However, at first glance you might think they were plants, as they are sessile (mainly sessile, anyhow) and have an overall form much like a kindergartner’s sketch of a flower. This morphology is where their common name, sea lilies, comes from.
Callan Bentley is Associate Professor of Geology at Piedmont Virginia Community College in Charlottesville, Virginia. He is a Fellow of the Geological Society of America. For his work on this blog, the National Association of Geoscience Teachers recognized him with the James Shea Award. He has also won the Outstanding Faculty Award from the State Council on Higher Education in Virginia, and the Biggs Award for Excellence in Geoscience Teaching from the Geoscience Education Division of the Geological Society of America. In previous years, Callan served as a contributing editor at EARTH magazine, President of the Geological Society of Washington and President the Geo2YC division of NAGT.