Monday, September 21, 2020

Something New From The Waldron Shale


UPDATE (11-13-2020): I now think this fossil is a cluster of holdfasts for cystoids. See my post about this here.

Last Saturday (09-19-2020) I visited a Waldron Shale site and found a fossil I have not seen before. At first I thought it might be some sort of colonial coral. I showed it to my cousin Kenny and he thought it might be a parasite on a crinoid column. Similar to a fossil he found in 2015, on a Mississippian Period fossil. See this posting for more info. See image below of a Mississippian crinoid stem with what appear to be galls from parasitic marine worms.

One can see the similarities with the current Waldron Shale find.

He will need to prep this new find to see there is a crinoid column this fossils are attached to or part of. These shapes do look similar to galls of putative myzostomids (small marine worm) on crinoids as seen on a page showing an image from the book Fossil Crinoids by Hans Hess, William I. Ausich, Carlton E. Brett, and Michael J. Simms (Cambridge University Press, 1999).

Upon further Internet searching I came across the Time Scavengers blog with a 2017 post about The College of Wooster's paleontologist Mark A. Wilson. He posted an image Upper Ordovician cobble with encrusting crinoids (three volcano-like fossils). These shapes have some similarity to this fossil find has well. Could they be a cluster of small crinoid holdfasts?

Link to scan of the paper on Tremichnus by Carlton E. Brett from 1985:

Link to paper Phosphannulus on Paleozoic Crinoid Stems by James R. Welch 1976:

Link to chapter entitled Biotic Interactions among Recent and among Fossil Crinoids by David L. Meyer and William I. Ausich. See section on Parasitism and Table V for information about parasites that infest crinoid.

Link to paper entitled Host-specific pit-forming epizoans on Silurian crinoids by Carlton E. Brett. The images show mostly boring holes and not the structures with holes seen in this fossil.

Link to article Phylogeny of Myzostomida (Annelida) and their relationships with echinoderm hosts by Mindi M. Summers and Greg W. Rouse.