Silurian Crinoid Arm/Stem? - Myelodactylus convolutus

This appears to be a Myelodactylus convolutus arm/stem found in Clark County, Indiana, USA in the Waldron Shale.  The fossil is from the Middle Silurian Period (around 425 to 419 million years ago).  High hopes that sand blasting will reveal more details of this fossil including the pinnules or feather looking part of the arm.

UPDATE (2020/02/16): Original post had this as unknown, but thanks to Kenny and ID has been found. Also this specimen was cleaned some more, see this posting https://louisvillefossils.blogspot.com/2010/06/silurian-crinoid-arm.html

Learn more about this unique crinoid from this article Myelodactylid crinoids from the Silurian of the British Isles by Stephen K Donovan and George D Sevastopulo from 1989 Palaeontology Volume 32 pages 689-710 at https://www.biodiversitylibrary.org/part/173971#/summary Plate 81 shows clear examples of what the calyx looked like though it might be somewhat different in the species of this fossil.

Arachnophyllum Coral

This coral is found in the Louisville Limestone and existed during the Middle Silurian Period (428-422 million years ago). It was called Arachnophyllum sp. and was found in Louisville, Kentucky.

E.C. Stumm's book Silurian and Devonian Corals of the Falls of the Ohio list a number of species of Arachnophyllum. The first is Arachnophyllum pentagonum (originally called Strombodes pentagonum, 1826) by George August Goldfuss its holotype is stored at the Paleontologisches Institut, Bonn University in Germany.

The next species is Arachnophyllum striatum (Favastraea striata, 1850) named by Alcide d'Orbigny. Its holotype is probably at the École des Mines in Paris, France. The picture below is of a specimen on display at the Natural History Museum in Paris, France.

The Arachnophyllum sinemurum was named by William J. Davis in 1887 (Strombodes sinemurus). The lectotype (specimen 8072 - now MCZ 105622) is stored at the Museum of Comparative Zoology at Harvard University, Cambridge, Massachusetts.

Edward Oscar Ulrich named Arachnophyllum separatum (Strombodes separatus, 1886).  Its holotype is in the Greene collection at the American Museum of Natural History in New York City, New York.


William J. Davis described the Arachnophyllum quadrangulare (Strombodes quadrangularis, 1887) in the monograph Kentucky Fossil Corals.  The holotype (specimen 8059 - now MCZ 105625) is stored at the Museum of Comparative Zoology at Harvard University, Cambridge, Massachusetts.

The geologist and artist with ties to New Harmony, Indiana, David Dale Owen is credited with describing the Arachnophyllum mammillare (Astrea mammillaris, 1844).  E.C. Stumm did not list a location of the holotype.

Silurian Period Pyrite Crinoid Stem

Pyrite on an unidentified crinoid stem from the Waldron Shale of Clark County Indiana, USA.  Crinoid lived in the Silurian Period.