An excellent specimen of Trepospira sphaerulata was recovered in late December 2021. It is a much better example of this species of Paleozoic gastropod, so I am replacing the content of this article with photos of it. New images should help future researchers search for an excellent example of this species. The specimen below, CG-0284, is from the Pine Creek limestone in Central Armstrong County, Pennsylvania.
Original Post from July 13, 2020.
Note: While the identification below is highly probable, it’s not definite. The specimen above (CG-0284) is a complete identification verified by two other invertebrate paleontologists.
This gastropod has a highly probable Identification. One can find the gastropod Trepospira sphaerulata in this and nearby limestone layers. Based on the nodes visible on the top of the last whorl, a local fossil gastropod expert gives this as a likely identification. This specimen comes from the Pine Creek Limestone locality, the source material for many of my recent posts.
The only fact keeping me from being sure is the lack of suture ornamentation. These should display as regular, raised nodes. However, this is a very flat, wide shell. The spire is visible as small and only increased in the very center.
Example showing ornamentation from the late 1800s
Winchell regarded the specimen below to be a perfect specimen. The suture ornamentation is very apparent.
Additional Photos of CG-0090
References for Trepospira sphaerulata
- Fossil works – Taxon Page
- Moore, R.C et al., 1960, Treatise on Invertebrate Paleontology, Part I, Mollusca 1, Page I201, I203
- Winchell, N.H., 1887, Geological and Natural History Survey of Minnesota: The Geology of Minnesota, V3, Pt2, Pg 1081.