Sunday, February 16, 2020

Myelodactylus convolutus Crinoid from Louisville Limestone

Recently, I have tried to put more effort in labeling a lot of collected fossils in my collection with names. At times difficult, due to poor note keeping by me when I picked them up or received them from someone else. So I sometimes rely on the previous posts to help figure out what was found and when. While looking back, I found that I had a number of unidentified fossil entries that I did not visit again to give a name. One was from May 10, 2010 which turns out to be a Myelodactylus convolutus? crinoid.

My cousin Kenny helped with the full name and sent me a picture of one from his collection seen above. This one is younger in that it was found in the Louisville Limestone and not the Waldron Shale. The fossil was found in the Jefferson County Kentucky USA and dates to the Middle Silurian Period. Also look at the blog post in 2014 showing one fully extended and attached with holdfast to a large coral.

This crinoid was unique in that the remains shown are believed to be its stem and not just an arm. In that inner coil would be a calyx with arms. Unless it was quite small on this species I do not see where the calyx is thus must have snapped off.

Refer to 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 Plate 81 shows clear examples of what the calyx looked like though it might be somewhat different in the species of this fossil