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

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.