What Fossils Lie Under Wind Cave? A First Inventory of the Park’s Paleontology

The prairie at Wind Cave National Park, Custer County, South Dakota. NPS photo by Ben Shreves.

Wind Cave is the third longest cave system in the United States and the seventh longest in the world, according to the National Park Service, and the park around it is a geological microcosm of the Black Hills, with formations from the Precambrian to the Late Quaternary. Several are fossil-bearing. In 2022 the park carried out its first paleontological resource inventory, with paleontology intern Theodore Herring documenting the fossil sites at the surface and inside the cave, and writing the article this page draws on.

What was done

Explorers have been recording fossils in the cave since 1891, and the park's record grew in the 1980s when its staff began working with paleontologists from the South Dakota School of Mines and Technology. Thousands of specimens have been collected since. The new project was meant to give staff and researchers a baseline. It assessed historical fossil sites, documented new ones, assessed collections, reviewed the research literature and interviewed current and former staff about the park's fossils and how to manage and interpret them.

Layer by layer

The cave itself. The Madison Limestone is the foundation of the park's caves: groundwater has repeatedly eroded voids in it over tens of millions of years, forming hundreds of miles of passages still being surveyed. Some fossil beds hold hundreds of brachiopod molds and casts. Brachiopods are the only fossils open to the public, on the Fairgrounds Tour Route. A newly documented brachiopod band runs around one cave room; graffiti on some shows that the early explorer Elmer McDonald and two companions found the room in 1894.

Graffiti from 1894 across several brachiopod molds and casts (image from NPS).

Conodonts. A USGS geologist found conodonts in the Minnelusa Formation in the early 2000s, but they had not been studied much since. More than a dozen specimens were collected and photographed in November 2022 for identification, which could allow a more precise date for the rock.

The White River Group. More than thirty localities have been documented, seven of them first found in the 1980s by a retired park biologist, Richard Klukas. The Centennial Site, found in the park's centennial year, 2003, became famous for a skull of Subhyracodon, a small hornless rhinoceros. The fossils indicate a dry, warm grassland in the Oligocene, similar in reconstruction to Badlands National Park despite the difference in altitude. Most sites have been dug thoroughly, but a Leptomeryx lower jaw, from a small deer-like ruminant, turned up in October 2022, and staff plan to keep monitoring in case more erodes out.

Recent bones

Salamander Cave has mammal fossils reaching back at least 250,000 years. Beaver Creek Shelter and Graveyard Cave have yielded thousands of Holocene bones. Persistence Cave, found in 2003 by a park physical scientist, has been under excavation since 2008 and may connect to Wind Cave, though that is unsurveyed. Volunteers helped dig in November 2022 in partnership with the Mammoth Site, which collects, sifts and stores the finds. One specimen is a pine marten that carbon dating puts at least 11,000 years old; the species is not found in the Black Hills today, which hints at local changes in fauna. A 6-foot-wide, 3-foot-deep sinkhole that opened in spring 2022 near a drainage exposed an ungulate pelvic bone not yet mineralized.

A public version of the final inventory report was expected later in the year of the article.

Sources

• National Park Service, Wind Cave Paleontological Resource Inventory, Park Paleontology News, article by paleontology intern Theodore Herring, Wind Cave National Park; rewritten in hubnx's own words.