Catalog Number: CG-0057

This is an exciting post, as it starts to describe what may become a new species of Mourlonia. The genus Mourlonia has a wide geologic time range, from 466 MYA to recent, marked as 0.012 MYA. Several examples have been defined from Carboniferous, and I am spending time now researching these examples. It seems probable that a carboniferous example of Mourlonia has not been found in this part of Pennsylvania, Ohio and West Virginia

Known examples exist from the Carboniferous in the Paleobiology Database. International examples include Antarctica, Australia, Iran, Ireland, Poland and the United Kingdom. Within the United States, examples are found in Alabama, Arkansas, Missouri, Nevada, Texas, Utah and Wyoming. However, some are listed specifically, and for the Westphalian (approx 318.1 to 306.9 MYA). there is a listing for Kentucky.

The Kentucky example is from the Coal Cliff/Hensley Member. In 1979, several specimens were sent to Charles Rice of the USGS for identification. USGS Paleontology and Stratigraphy Branch describes these under report no. PR-0205. Unfortunately, I have not been able to obtain the report yet. It’s likely I won’t find photos. They also forgot to mark the genus in their formation correlation chart:

Appendix C showing Mourlonia with corrected placement
Appendix C from the Kentucky publication. Blue highlight marking a missing dot. Notice the Brush Creek Ls. listed in top right.

The candidate Mourionia specimen.

Below is the photo of the specimen when I first found it. It separated from it’s spire as part of a hammered limestone split. When I first saw it, I noticed the detailed whorl pattern. The growth lines present in a prosocline (forward slanted) pattern. Gastropod shells have a whole dictionary of terms to learn. Here are the 5 types just for growth lines.

TermDefinition
OpisthocyrtArched backwards
OptisthoclineLearning away from growth direction
OrthoclineStraight Down
ProsoclineLeaning towards growth direction
ProsocyrtArches forward
Directional terminology for growth lines in a dextral shell.
Gastropod dextral shell directional terminology
Gastropod dextral shell directional terminology
Mourlonia
The specimen as I first saw it.

Discovery and light preparation work

After viewing the interesting and beautiful shell pattern from a fresh split piece of Brush Creek Limestone, I set the piece aside. I then cut a rectangle or matrix from the rock to save the specimen in a much smaller form. Typically when I try to further extract gastropods, they will shatter. In turn, I either set these aside or wait for something better to come around.

I sent a photo of the growth lines to John A. Harper, someone who has written several papers on Paleozoic Gastropods. In the evening, I lightly prepped the specimen. I was careful to not hit the shell and only remove what was already easy to remove. Upon inspection, there were several pieces of fragment shell pieces near the specimen. This makes it very easy to remove the matrix closer to the shell to see more of the pattern. If only I could get down to the selenizone, full identification would be much more possible.

Later that night, John got back to me and said it’s likely a genus that has never been found in the tri-state area. After taking further photos and shooting a small video to show it better dimension-ally, he determined that it’s likely this is the first Mourlonia found in this area. Next steps would be to present the specimen to him in person, however the current shelter-in-place rules for Covid-19 makes that difficult. So for now, I shall keep it safe and wait for a more appropriate time.

Gallery of Mourlonia Specimen Photos

References for Mourlonia

  • Genus Page – Fossilworks
  • 2001, S. R. A. Kelly, P. A. Doubleday, C. H. C. Brunton, J. M. Dickins, G. D. Sevastopulo and P. D. Taylor. First Carboniferous and Permian marine macrofaunas from Antarctica and their tectonic implications. Journal of the Geological Society of London 158(2):219-232
  • 1991, Chesnut, Donald R. Jr., “Paleontological Survey of the Pennsylvanian Rocks of the Eastern Kentucky Coal Field: Part 1, Invertebrates”. Kentucky Geological Survey Information Circular. 46.