Dolatocrinus triangulatus? Crinoid Calyx Fossil

This appears to be a Dolatocrinus triangulatus? (Barris, 1878) crinoid calyx fossil. It was found in the Thunder Bay Formation of Alpena Michigan, USA. It dates to the Middle Devonian Period (Erian).

Learn more at the michiganbasinfossils.org web site.

Thanks to Mary Ann for letting me take some pictures of this fine specimen. 

Species was named by Willis Hervey Barris (1821-1901) in 1878 in New Fossils from the Corniferous Formation at Davenport published Proceedings Davenport Academy of Sciences, Volume 2, pages 282-288, plates 10 and 11. Genus is attributed to S. S. Lyon in the Paleontological Report Geological Survey of Kentucky, 1856-1857 pages 465-498.