Plant and invertebrate macrofossils from the Pipe Creek Sinkhole (Late Neogene), Grant County, Indiana

ABSTRACT

Examination of macrofossils from the late Neogene Pipe Creek Sinkhole in Indiana, USA, yielded 15 distinct plant taxa, one fungal taxon, and six invertebrate taxa. The plant assemblage was dominated by terrestrial taxa both in richness and abundance. Of the 12 terrestrial plant taxa, eight were trees or shrubs including two Carya spp., Corylus sp., Fraxinus sp., aff. Pinaceae, Quercus sp., aff. Rosaceae, and an unknown gymnosperm, possibly Ginkgophyta or Cycadophyta. Fossil nuts of a new species, Carya pipecreekensis Swinehart and Farlow sp. nov., are described. Other terrestrial plant macrofossils include a species of Asteraceae, Vitis sp., Xanthium sp., and Poaceae indet. Charcoalified remains of wood, Asteraceae achenes, and Poaceae crowns suggest fires were an important factor in ecosystem structure. Condition of some of the macrofossils suggests high-energy, post-depositional transport. Aquatic species include the plants Chara sp. and two Potamogeton spp. as well as the animals Helisoma sp., Physa sp., Sphaeriidae, and ostracoda. The terrestrial flora suggests a temperate woodland savanna community with a canopy that includes Carya, Fraxinus, Quercus, Corylus, and Pinaceae, a sub-canopy with Vitis, and a ground flora with a species of Asteraceae and abundant Poaceae. The assemblage shares elements and characteristics with the similarly-aged Gray Fossil Site in Tennessee.

KEYWORDS:

• Late Neogene
• Carya pipecreekensis
• plant macrofossils
• Indiana
• Pipe Creek Sinkhole
• palaeoecology

Acknowledgments

The authors thank Irving Materials, Inc., especially John Havens, Rick Lucas, and Ray Rich, for access to the site and much assistance throughout the excavation; Ron Richards and staff and volunteers from the Indiana State Museum for extensive fieldwork and sample preparation; Hillsdale College students Aaron Hoekje and Katherine Ohlstrom for assistance in macrofossil sorting and mensuration; Dr. Bruce Tiffney, University of California Santa Barbara, for helpful comments on a draft of the manuscript and on seed identification; Dr. Elisabeth Wheeler, North Carolina State University, for help in the identification of the Fraxinus wood; Dr. Cathy Aime, Purdue University, for verifying the determination of the aff. Sardariomycete fungus; Dr. Hilary H. Birks, University of Bergen, for helpful comments on achene identification and preparation; Dr. David Dilcher, University of Florida, for assistance identifying and characterizing the taphonomy of leaf impressions; Hillsdale College and the Argast Family Imaging and Analysis Lab at Purdue Fort Wayne for funding the radiocarbon dates; Dr. Joseph Garnjobst, Professor of Latin at Hillsdale College; and three anonymous reviewers for extremely helpful comments on the manuscript. J.O.F. thanks the National Science Foundation (Award No. 0207182), the National Geographic Society (Grant No. 9408-13), and the Indiana Academy of Science for funding the fieldwork that produced the materials examined in the present study.

Disclosure statement

The authors have no relevant financial or non-financial competing interests to report.

Supplementary material

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