Archive for November 24th, 2013

Wooster’s Fossil of the Week: A crinoid calyx from the Lower Carboniferous of Iowa

November 24th, 2013

Macrocrinus verneuilianus (Shumard, 1855) 585In honor of Echinoderm Week for my Invertebrate Paleontology course, we have a beautiful crinoid calyx (or crown, or just “head”) on a slab from the Burlington Limestone (Lower Carboniferous, Osagean) found near Burlington, Iowa. I inherited this fossil when I arrived at Wooster, so I have no idea who collected it or when. The handwritten number is similar to those on many of our 19th century specimens. The sharp features of the specimen have been a bit dulled by a preparation technique that probably involved abrasives.

The crinoid is Macrocrinus verneuilianus (Shumard, 1855) of the Order Monobathrida. It is unusual in that it is preserved with its filter-feeding arms intact, along with a magnificent anal tube (see closer view below).
Macrocrinus anal chimney 585The anal tube, sometimes called an anal chimney, is just what you guessed it would be — an anus at the end of a long pipe of calcitic plates. Its primary purpose was all about hygiene. The tube allowed waste products to be whisked away far from the mouth of the crinoid, which was at the base of the arms. Some researchers suggest that the long tube served another function as well: it may have helped stabilize and direct the filter-feeding fan of outstretched arms in a stiff current, something like the tail of an airplane or a panel on a weather vane.

Macrocrinus verneuilianus (Shumard, 1855) diagramFigure of Macrocrinus verneuilianus (9) from “Paleontology of Missouri” (1884) by Charles Rollin Keyes. That long anal tube is not exaggerated!
Shumard585Benjamin Franklin Shumard (1820-1869) named Macrocrinus verneuilianus in 1855. As you might have deduced from his name, Shumard was a Pennsylvanian, having been born in Lancaster. He received his bachelor’s degree from Miami University in Oxford, Ohio, and then later earned an MD in Louisville, Kentucky, in 1843. As a young doctor in Kentucky, he began to collect fossils as a hobby. After just three years of medicine, he gave it up to pursue a career as a geologist. (Those Kentucky fossils must have been particularly fine!) By 1848 he was on geological surveys for Minnesota, Wisconsin and Iowa, and in 1850 he went on a geological survey expedition to Oregon. (Imagine that trip in 1850.) In 1853 he became the paleontologist in the Missouri Geological Survey. In 1858 he left Missouri to begin the first Geological Survey in Texas. The Civil War must have caused him considerable pain, since he was a Pennsylvanian in Texas. He moved to St. Louis and renewed his medical career in 1861. In 1869, he decided to move south to New Orleans for health reasons. The steamship he took burned to the waterline one evening north of Vicksburg. He was safely rescued, but contracted pneumonia in the process. He returned quickly to St. Louis and there died at 49 years of age. At the time of his death Shumard was president of the St. Louis Academy of Science and a member of the Geological Societies of London, France, and Vienna, and he was also a member of the academies of science in Philadelphia, Cincinnati, and New Orleans. No doubt we would have had much more scientific accomplishment from this young paleontologist had he lived longer.

References:

Ausich, W.I. 1999. Lower Mississippian Burlington Limestone along the Mississippi River Valley in Iowa, Illinois, and Missouri, USA, p. 139-144. In: H. Hess, W.I. Ausich, C.E. Brett and M.J. Simms (eds.), Fossil Crinoids, Cambridge University Press.

Ausich, W.I. and Kammer, T.W. 2010. Generic concepts in the Batocrinidae Wachsmuth and Springer, 1881 (Class Crinoidea). Journal of Paleontology 84: 32-50.

Lane, N.G. 1963. Two new Mississippian camerate (Batocrinidae) crinoid genera. Journal of Paleontology 37: 691-702.

Shumard, B.F. 1855. Description of new species of organic remains. Missouri Geological Survey 2:185–208.