Subclass Caenogastropoda
Order incertae
Superfamily Soleniscoidea Knight, 1931
Family Meekospiridae Knight, 1936
Genus Meekospira Ulrich & Scofield, 1897
Species peracuta Meek & Worthen, 1860

Fossils from this family are widespread in the transition later atop the Pine Creek limestone at SL 6445, especially Meekospira Ulrich & Scofield 1897, the type for the family. Fauna within the family does not have a columellar fold nor an anterior notch (Knight 1960). These are found in the fissile area. A few are found with a very sharp protoconch, which often has a different morphology than the adult shell. The shells stick out of the eroding rocks and preserve great details. The following figures show well-detailed specimens of Meekospira peracuta (Meek & Worthen, 1861). The fragility of each is difficult to manage, where a simple act of clumsiness can knock off a spire tip and protoconch that has been attached for over 305 million years. Figure 1-A shows a well-preserved spire.

Meekospira peracuta from SL 6445. A, medium-size specimen without the protoconch, the rounded bottom of the aperture easily visible, CG-0441; B, CG-0442; C, CG-0443. Scale bar = 5 mm.
Fig. 1.—Meekospira peracuta from SL 6445. A, medium-size specimen without the protoconch, the rounded bottom of the aperture easily visible, CG-0441; B, CG-0442; C, CG-0443. Scale bar = 5 mm.
Fig. 2.—Meekospira peracuta from SL 6445. A, CG-0430; B, a clean column showing the nature of its shape, CG-0431; C, CG-0440. Scale bar = 5 mm.
Fig. 2.—Meekospira peracuta from SL 6445. A, CG-0430; B, a clean column showing the nature of its shape, CG-0431; C, CG-0440. Scale bar = 5 mm.
Meekospira peracuta from SL 6445.
Fig. 3.—Meekospira peracuta from SL 6445. A, CG-0491; B, CG-0492; C, CG-0493. Scale bar = 5 mm.

References

  • Knight, J.B., 1931, The gastropods of the St. Louis, Missouri, Pennsylvanian outlier: the Subulitidae. Journal of Paleontology 5(3):177-229
  • Knight J.B., 1936, Notes on Paleozoic Gastropoda. Journal of Paleontology 10(6):520-534
  • Meek, F.B., and Worthen, A.H., 1860, Description of new Carboniferous fossils from Illinois and other western states. Proceedings of the Academy of Natural Sciences of Philadelphia 12:447-472
  • Ulrich, E.O., and Scofield, W.H., 1897, The Lower Silurian Gastropoda of Minnesota. The Paleontology of Minnesota 39(2):813-1081