Thunder lizard handstands: Manus-only sauropod trackways from the Glen Rose Formation (Lower Cretaceous, Kendall County, Texas)

Abstract

Three parallel, manus-only sauropod trackways from the Coffee Hollow A-Male tracksite (Glen Rose Formation, Kendall County, Texas) were studied separately by researchers from the Heritage Museum of the Texas Hill Country and the Houston Museum of Natural Sciences. Footprint and trackway measurements generally show good agreement between the two groups’ data sets. Footprints appear to be shallowly impressed true tracks rather than undertracks. One of the Coffee Hollow trackways shows marked asymmetry in the lengths of paces that begin with the left as opposed to the right forefoot, and two of the Coffee Hollow trackways are unusually broad. The Coffee Hollow trackways differ enough from the manus portions of other Glen Rose Formation sauropod trackways to suggest that they were made by a different kind of sauropod. Greater differential pressure exerted on the substrate by the forefeet than the hindfeet probably explains the Coffee Hollow trackways, like other manus-only sauropod trackways, but the possibility that they indicate unusual locomotion cannot at present be ruled out.

Keywords:

• Sauropods
• ichnology
• manus-only trackways
• Glen Rose Formation

Acknowledgments

This paper is dedicated to the memory of R.T. Bird and Wann Langston. We commend Ms. Gail Flach and her associates for their recognition of the importance of the site, and for interrupting quarry work while study proceeded. Numerous volunteers assisted in cleaning and documenting the tracksite. For two days, 21 members of the Heritage Museum of the Texas Hill Country volunteered to clean, measure, photograph, trace, and map the tracksite. We thank Matt Bonnan, Don Henderson, Christian Meyer, Jens Lallensack, and Brian Platt for useful discussions or unpublished data, and Brian Platt (again) and the University of Arkansas Center for Advanced Spatial Technologies for providing the LIDAR image of a portion of the Briar Site (CertainTeed Gypsum mine). Hendrik Klein and John Foster made several helpful comments on the manuscript. Jim Whitcraft assisted in the production of illustrations.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research was supported by a grant from the National Geographic Society to Farlow. The Department of Library Services of the American Museum of Natural History kindly granted permission to reproduce some of R.T. Bird’s images of the Mayan Ranch site.