Friday, November 13, 2020

Waldron Shale Cystoid Holdfasts?


On September 21, 2020, I posted this fossil but was unsure what exactly it was. After consulting with my cousin Kenny and Ken (a Waldron Shale fossil hunter of over 40 years), I am leaning toward and identification that this fossil is a cluster of cystoid holdfasts.

Kenny showed me a paper entitled Taphonomy of diploporite (Echinodermata) holdfasts from a Silurian hardground, southeastern Indiana, United States:palaeoecologic and stratigraphic significance by James R. Thomka and Carlton E. Brett published in 2014 at Geol. Mag. 151 (4) in 2014 pages 649-665. It shows a variety of fossils similar to the one pictured that are thought to be parts of Silurian cystoid fossils.

A link to that paper is here:

The fossil was found the Silurian Period (Wenlock: Homerian Stage) in Clark County Indiana, USA. If this fossil is a series of holdfasts, then they grew in close proximity to one another.

I have found numerous cystoids in the Waldron Shale notably Caryocrinites (Say, 1825) and Holocystites (Hall 1864) aka Megacystites (Hall, 1865). See previous entries: