Publications

Peer-reviewed publications

# graduate student; % undergraduate student

28. Butreddy, P., Mergelsberg, S.T., Jocz, J.N., Li, D., Prabhakaran, V., Ritchhart, A.J., Subban, C.V., Kellar, J., Beeler, S.R., Keenan, S.W., and Nakouzi, E. (2025). Selective dissolution and re-precipitation by pH cycling enables recovery of manganese from surface nodules. RSC Sustainability, DOI: 10.1039/d4su00444b.

27. DeBruyn, J.M, Keenan, S.W., and Taylor, L.S. (2024). Review: From carrion to soil: microbial recycling of animal carcasses. Trends in Microbiology, DOI:10.1016/j.tim.2024.09.003. 

26. Keenan, S.W. and Beeler, S.R. (2023). Long-term effects of buried vertebrate carcasses on soil biogeochemistry in the Northern Great Plains. PLOS ONE, DOI:10.1371/journal.pone.0292994.

25. Keenan, S.W., Emmons, A.L., and DeBruyn, J.M. (2023). Microbial community coalescence and nitrogen cycling in simulated mortality decomposition hotspots. Ecological Processes, DOI:10.1186/s13717-023-00451-y.

24. Keenan, S.W. (2023). Thermodynamic stabilities of apatite in a wetland system: implications for bone diagenesis. Applied Geochemistry, 148: 105546, DOI:10.1016/j.apgeochem.2022.105546. 

23. Sullivan, C.A.# and Keenan, S.W. (2022). Experimental dissolution of fossil bone under variable pH conditions. PLOS ONE DOI:10.1371/journal.pone.0274084. 

22. Emmons, A.L., Mundorff, AZ., Hoeland, K.M., Davoren, J., Keenan, S.W., Carter, D.O., Campagna, S.R., and DeBruyn, J.M. (2022). Postmortem skeletal microbial community composition and function in buried human remains. mSystems DOI:10.1128/msystems.00041-22. 

21. Gladstone, N.S. #, Pieper, E.B., Keenan, S.W., Paterson, A.T., Slay, M., Dooley, K., Engel, A.S., and Niemiller, M.L. (2021). Discovery of the Blue Ridge Springsnail, Fontigens orolibas, Hubricht, 1957 (Gastropoda: Emmericiidae) in east Tennessee and its conservation implications. Freshwater Mollusk Biology and Conservation, 24: 34-42.

20. Emmons, A.L. #, Mundroff, A.Z., Keenan, S.W., Davoren, J., Andronowski, J., Carter, D. O., and DeBruyn, J.M. (2020). Characterizing the postmortem human bone microbiome from surface decomposed remains. PLoS One, 15:e0218636, DOI:10.1371/journal.pone.0218636.

19. Fanter, C.E. #, Lin, Z., Keenan, S.W., Janzen, F.J., Mitchell, T.S., and Warren, D.E. (2020). Development-specific transcriptomic profiling suggests new mechanisms for anoxic survival in the ventricle of overwintering turtles. Journal of Experimental Biology, 223, DOI: 10.1242/jeb.213918.

18. Keenan, S.W., Schaeffer, S. M., and DeBruyn, J.M. (2019). Spatial changes in soil stable isotopic composition in response to carrion decomposition. Biogeosciences, DOI: 10.5194/bg-16-3929-2019.

17. Keenan, S.W. and DeBruyn, J. M. (2019). Changes to vertebrate tissue stable isotope (δ15N) composition during decomposition. Scientific Reports, 9:9929, DOI: 10.1038/s41598-019-46368-5.

16. Keenan, S.W., Pasteris, J.D., Wang, A., and Warren, D.E. (2019). Heterogeneous bioapatite carbonation in western painted turtles is unchanged after anoxia. Comparative Biochemistry and Physiology, Part A, 233: 74-83.

15. Keenan, S.W., Emmons, A.L. #, Taylor, L.S. #, Phillips, G., Mason, A.R. #, Mundorff, A., Bernard, E.C., Davoren, J., and DeBruyn, J.M. (2018). Spatial impacts of a multi-individual grave on microbial and microfaunal communities and soil biogeochemistry. PLoS One, DOI: 10.1371/journal.pone.0208845.

14. Odegard, D.T. #, Sonnenfelt, M.A. %, Bledsoe, J.G., Keenan, S.W., Hill, C.A, and Warren, D.E. (2018). Changes in the material properties of the shell during simulated aquatic hibernation in the anoxia-tolerant painted turtle. Journal of Experimental Biology, DOI: 10.1242/jeb.176990. 

13. Keenan, S.W., Schaeffer, S.M., Jin, V.L., and DeBruyn, J.M. (2018). Mortality hotspots: nitrogen cycling in forest soils during vertebrate decomposition. Soil Biology and Biochemistry, 121: 165-176.

12. Keenan, S.W., Widga, C., DeBruyn, J.M., and Schaeffer, S.M. (2018). Nutrient hotspots through time: a field guide to modern and fossil taphonomy in East Tennessee in Engel, A.S. and Hatcher, B., eds., Field Guide 50: 2018 Southeastern Section Meeting Field Guide, pp. 61-74.

11. Keenan, S.W. and Engel, A.S. (2017). Reconstructing diagenetic conditions of bone at the Gray Fossil Site, Tennessee, USA. Palaeogeography, Palaeoclimatology, Palaeoecology, 471: 48-57.

10. Keenan, S.W. and Engel, A.S. (2017). Early diagenesis and recrystallization of bone. Geochimica et Cosmochimica Acta, 196: 209-223.

9. Keenan, S.W. and Tellez, M. (2016). Trachemys scripta elegans (Red-eared slider) and Chrysemys picta bellii (Western painted turtle). Endoparasites. Herpetological Review, 47(3): 451-453.

8. Keenan, S.W. (2016). From bone to fossil: a review of the diagenesis of bioapatite. American Mineralogist, 101: 1943-1951.

7. Keenan, S.W., Engel, A.S., Roy, A., and Bovenkamp-Langlois, G.L. (2015). Evaluating the consequences of diagenesis and fossilization on bioapatite lattice structure and composition. Chemical Geology, 413: 18-27.

6. Keenan, S.W., Hill, C.A. #, Kandoth, C., Buck, L.T., and Warren, D.E. (2015). Transcriptomic response of the western painted turtle heart and telencephalon to anoxia. PLoS One, DOI: 10.1371/journal.pone.0131669.

5. Keenan, S.W. and Elsey, R.M. (2015). The good, the bad, and the unknown: microbial symbioses of the American alligator. Integrative and Comparative Biology, DOI: 10.1093/icb/icv006.

4. Keenan, S.W., Niemiller, M.L., and Williams, B.W. (2014). Observations of Cambarus bartonii cavatus (Decapoda: Cambaridae) and ectosymbiotic branchiobdellidans (Annelida: Clitellata) in Cruze Cave, Knox County, Tennessee, USA. Speleobiology Notes, 6: 55-61.

3. Keenan, S.W. and Ellwood, B.B. (2014) Geophysical evaluation of the Richland and Holloway Mounds, southeastern Louisiana, U.S.A. Geoarchaeology, 29: 312-325.

2. Keenan, S.W. and Scannella, J.B. (2014). Paleobiological implications of a Triceratops bonebed from the Hell Creek Formation, Garfield County, northeastern Montana. In (Wilson, G.P., Clemens, W.A., Horner, J.R., and Hartman, J.H., eds.) Through the end of the Cretaceous in the type locality of the Hell Creek Formation in Montana and adjacent areas. Geological Society of America Special Paper 503. Pp. 349-364.

1. Keenan, S.W., Engel, A.S., and Elsey, R.M. (2013). The alligator gut microbiome and implications for archosaur symbioses. Scientific Reports, DOI: 10.1038/srep02877.

Other Publications

5. Keenan, S.W. and Tellez, M. (2023). Chapter 7: Symbiotic associations in crocodylians: present, past, and future. Eds. Ballard, H.W. and Farlow, J. in Ruling Reptiles: Crocodylian biology and archosaur paleobiology, Indiana University Press, Bloomington, Indiana. 123-149. 

4. Keenan, S.W. (2019). Fossilization. In: Alderton, D., Elias, S. (eds.), Encyclopedia of Geology, 2nd edition, Academic Press: London. 3: 1-11

3. Keenan, S.W., Paterson, A.T., Niemiller, M.L, Slay, M.E., Clark, S.A., and Engel, A.S. (2017). Observations of the first stygobiont snail (Hydrobiidae, Fontigens sp.) in Tennessee. Proceedings of the 17th International Congress of Speleology, Sydney, Australia, pp. 91-91.

2. Engel, A.S., Niemiller, M.L., Zigler, K.S., Stephen, C.D.R., Carter, E.T., Paterson, A.T., Keenan, S.W., and Taylor, S.J. (2017). Invertebrate and vertebrate cave fauna records for the Appalachian Valley and Ridge. Proceedings of the 17th International Congress of Speleology, Sydney, Australia, pp. 82-86.

1. Keenan, S.W. (2013). Freshwater vertebrate animal metagenomics, Alligatorinae. In: Nelson, K. (ed.), Encyclopedia of Metagenomics, Springer, DOI: 10.1007/978-1-4614-6418-1_101-8.

Abstracts (last five-ish years)

# = student

2025:

Keenan, S.W.* and Beeler, S.R. The bone that go away: consequences of dissolution on fossil bone geochemistry and implications for paleoenvironmental reconstructions. Goldschmidt (oral presentation). 

Beeler, S.R.*, Khatri, S.I.#, Kortenbusch, R.A.#, Pagnac, D., and Keenan, S.W. Geochemistry of lacustrine limestones from the White River Group of South Dakota, USA and their implications for understanding the Eocene-Oligocene Transition. Goldschmidt (oral presentation). 

2024:

Keenan, S.W.* and Beeler, S.R. Here today, gone tomorrow: dissolution of fossil bone under a changing climate. Geological Society of America (oral presentation). 

Nystuen, M.*# and Keenan, S.W. Sedimentological analysis of the Big Buffalo Quarry, Badlands National Park, South Dakota. Geological Society of America (poster). 

Van Winkle, A.R.*#, Kellar, J., and Keenan, S.W. Developing a remote sensing process to idenfity coltan artisanal mines in the Democratic Republic of the Congo. Geological Society of America (poster). 

DeBruyn J.M.*, Mason, A.R., Keenan, S.W., and Taylor, L.S. Soil microbial community succession in carcass decomposition hotspots. Ecological Society of America Annual Meeting (invited oral presentation). 

Wright, S.*, Fox, N., Olive, G.#, Rodarte, D.#, Keenan, S.W., and Pagnac, D. Mining for Blancan Gold: The Richmond Hill Local Fauna of the Black Hills, South Dakota. North American Paleontological Convention (oral presentation). 

Kortenbusch, R.*#, DeBoer, R.*#, Keenan, S.W., and Beeler, S.R. Geochemical assessment of subsurface waters and secondary mineral precipitates at the Sanford Underground Research Facility in Lead, South Dakota. Western South Dakota Hydrology Conference (poster). 

Beeler, S.R.*, Keenan, S.W., Kortenbusch, R.#, and DeBoer, R.# Assessing the geochemical variability of groundwater from the Sanford Underground Research Facility in Lead, SD. Western South Dakota Hydrology Conference (oral presentation). 

2023:

Keenan, S.W., McAndrew, C.#, and Beeler, S.R. Disentangling carcass size and climate effects on soil biogeochemistry during decomposition. Symposium of the International Societies for Environmental Biogeochemistry and Subsurface Microbiology, Banff, Canada (oral presentation).

Rodarte, D.# and Keenan S.W. The effects of microbial activity on bone microstructure and collagen. Geological Society of America Annual Meeting, Pittsburgh, PA (poster presentation).

2022:

Beeler, S.R. and Keenan, S.W. Assessing changes in lipid biomarkers in soils associated with animal decomposition over decadal time scales. Geological Society of America Annual Meeting, Denver, CO. Geological Society of America Abstracts with Programs, 54:5, doi.org/10.1130/abs/2022AM-379466 (poster).

Keenan, S.W., Beeler, S.R., DeBruyn, J.M., and Mason, A.R.# Beaver decomposition leaves long-lasting biogeochemical impacts on surface and subsurface soils. Geological Society of America Annual Meeting, Denver, CO. Geological Society of America Abstracts with Programs, 54:5, doi.org/10.1130/abs/2022AM-378779 (invited oral presentation).

Rich, A.# and Keenan, S.W. Lithological influences on mosasaur fossil taphonomy within the Pierre Shale Formation of South Dakota. Geological Society of America Annual Meeting, Denver, CO. Geological Society of America Abstracts with Programs, 54:5, doi.org/10.1130/abs/2022AM-377171 (poster).

Sullivan, C.A.# and Keenan, S.W. Quantitative assessment of fossil bone dissolution under acidic conditions—implications for guiding field collection efforts. Geological Society of America Annual Meeting, Denver, CO. Geological Society of America Abstracts with Programs, 54:5, doi.org/10.1130/abs/2022AM-383090 (oral presentation).

Whittenberg, W.# and Keenan, S.W. The use of medical CT scanning to analyse ammonoid shell wall thickness as a response to predation. Geological Society of America Annual Meeting, Denver, CO. Geological Society of America Abstracts with Programs, 54:5, doi.org/10.1130/abs/2022AM-383584 (poster).

Keenan, S.W., Cyrier, M.#, Hagen, S.%, and Melancon, A.% Integrating Black Hills caves into undergraduate geology research at South Dakota School of Mines and Technology. National Speleological Society Convention, Rapid City, SD (oral presentation)

Keenan, S.W. and Cyrier, M.# Microbial habitability of Black Hills caves: a geochemical perspective. Conference on Science at the Sanford Underground Research Facility, Rapid City, SD (invited oral presentation).

Keenan, S.W. and Beeler, S.R. Long-term impacts of buried animal carcasses on soil biogeochemistry in the Northern Great Plains. Geological Society of America, Rocky Mountain Section Meeting, Las Vegas, NV (oral presentation).

2021:

Cyrier, M.# and Keenan, S.W. Seasonal fluctuations of subsurface conditions in Rushmore Cave, Keystone, SD. Geological Society of America Annual Meeting, Portland, OR (poster).

Cyrier, M.# and Keenan, S.W. Seasonal fluctuations of subsurface conditions in Rushmore Cave, Keystone, SD. Rocky Mountain Geobiology Symposium, Golden, CO (poster).

DeVault, G.A.# and Keenan, S.W. Using tooth fossil bone geochemistry and age reports to reconstruct diagenesis at the Pig Dig Site, Badlands National Park, SD. Geological Society of America Annual Meeting, Portland, OR (poster).

Sullivan, C.# and Keenan, S.W. Vertebrate fossil dissolution rates at varying pH: a pilot study. Geological Society of America Annual Meeting, Portland, OR (poster).

2020:

DeVault, G.A.# and Keenan, S.W. Using tooth wear and decomposition to interpret geochemistry in paleontological localities. Geological Society of America (poster, online).

Keenan, S.W. and DeBruyn, J.M. Surface and subsurface vertebrate decomposition result in protracted soil nitrogen stable isotopic enrichment. Rocky Mountain Section of the Geological Society of America, Provo, Utah (May; oral presentation, cancelled due to COVID-19).

Cyrier, M.*%, Chase, K., and Keenan, S.W. Impacts of seasonality on subsurface conditions in Rushmore Cave, South Dakota. Rocky Mountain Geobiology, Golden, CO (April; *presenter, cancelled due to COVID-19).

2019:

Keenan, S.W. and DeBruyn, J. M. Quantifying the long-term impacts of animal decomposition on soil biogeochemical cycling. Geological Society of America, Phoenix, AZ (poster presentation).

Keenan, S.W. + Temporal and spatial dynamics of animal decomposition in terrestrial systems. Geobiology Symposium, Banff, Canada (+invited oral presentation).

Driebergen, J.*#, Keenan, S.W. Cosmopolitan anuran assemblages: proxies for the effects of climate change? Society of Vertebrate Paleontology, Brisbane, Australia (*presenter).

Emmons, A.L.*#, Keenan, S.W., Davoren, J., DeBruyn, J.M., Carter, D., and Mundorff, A.Z. DNA preservation in bone in a multi-individual burial. Proceedings of the American Academy of Forensic Sciences, Baltimore, MD (*presenter).

Mason, A.R*#, Keenan, S.W., Emmons, A.L. #, Taylor, L.S. #, Phillips, G., Mundorff, A.Z., Bernard, E.C., and DeBruyn, J.M. Spatial impact of a multi-individual grave on soil biochemistry and microbial ecology. Soil Science Society of America, San Diego, CA (*presenter).