Data release for Seasonality of precipitation in the southwestern United States during the late Pleistocene inferred from stable isotopes in herbivore tooth enamel

Dates

Publication Date: 2022-10-06
Start Date: 2013
End Date: 2022

Citation

Kohn, M.J., Springer, K.B., Pigati, J.S., Reynard, L., Drewicz, A.E., Crevier, J., and Scott, E., 2022, Data release for Seasonality of precipitation in the southwestern United States during the late Pleistocene inferred from stable isotopes in herbivore tooth enamel: U.S. Geological Survey data release, https://doi.org/10.5066/P9DBH6V7.

Summary

The late Pleistocene was a climatically dynamic period, with abrupt shifts between cool-wet and warm-dry conditions. Increased effective precipitation supported large pluvial lakes and long-lived spring ecosystems in valleys and basins throughout the western and southwestern U.S., but the source and seasonality of the precipitation are debated. Here we present stable carbon and oxygen isotope data from tooth enamel of late Pleistocene herbivores recovered from paleowetland deposits at Tule Spring Fossil Beds National Monument in the Las Vegas Valley of southern Nevada, as well as modern herbivores from the surrounding area, to investigate whether winter or summer precipitation was responsible for driving the wet hydroclimate conditions [...]

Summary

The late Pleistocene was a climatically dynamic period, with abrupt shifts between cool-wet and warm-dry conditions. Increased effective precipitation supported large pluvial lakes and long-lived spring ecosystems in valleys and basins throughout the western and southwestern U.S., but the source and seasonality of the precipitation are debated. Here we present stable carbon and oxygen isotope data from tooth enamel of late Pleistocene herbivores recovered from paleowetland deposits at Tule Spring Fossil Beds National Monument in the Las Vegas Valley of southern Nevada, as well as modern herbivores from the surrounding area, to investigate whether winter or summer precipitation was responsible for driving the wet hydroclimate conditions that prevailed in the region during the late Pleistocene. Tooth enamel δ18O values for Equus, Bison, and Mammuthus are generally low (average 22.2±0.7‰, 2 s.e., VSMOW) compared to modern equids (26.1±1.0‰), and imply lower water δ18O values (–16.5 ±0.8‰) than what is observed in active springs and wells in the Las Vegas Valley (–12.9‰) or implied by modern equids and a local calibration of equid and water compositions (-12.2±1.1‰). Notably, Camelops generally yielded higher δ18O values (23.7±1.1‰), possibly suggesting drought tolerance. Mean δ13C values for the Pleistocene grazers (–6.4±0.8‰, 2 s.e., VPDB) are considerably higher than for modern equids (-10.4±0.4‰) and indicate more consumption of C4 grass (18±6%) than today 0±3%). However, calculated C4 grass consumption in the late Pleistocene is strikingly lower than the amount of C4 grass taxa currently present in the valley (55-60%) which is unexpected in the context of widespread C4 grassy patches. δ13C values in Camelops tooth enamel (-7.4±1.2‰) are interpreted as reflecting moderate consumption (16±9%) of Atriplex (saltbush), a C4 shrub that flourishes in regions with hot, dry summers. Lower water δ18O values, lower abundance of C4 grasses, and the inferred presence of Atriplex are all consistent with general circulation models that show the enhanced winter moisture delivered into the interior western U.S. during the late Pleistocene was sourced from the north Pacific, but do not support alternative models that infer enhanced summer precipitation was sourced from the tropics. In addition, we hypothesize that dietary competition between the diverse and abundant Pleistocene fauna may have driven the grazers analyzed here to feed preferentially on C4 grasses. Dietary partitoning, especially when combined with decreased pCO2 levels during the late Pleistocene, could readily explain the relatively high δ13C values observed in late Pleistocene grazers in the Las Vegas Valley and elsewhere in the southwestern U.S. without the input of additional summer precipitation as it has been interpreted previously. This suggests that Pleistocene hydroclimate parameters derived from floral records may need to be reevaluated in the context of the potential effects of dietary preferences and lower pCO2 levels on the stability of C3 vs. C4 plants.

Contacts

Point of Contact :: Jeffrey S Pigati
Originator :: Matthew J Kohn, Kathleen B Springer, Jeffrey S Pigati, Linda Reynard, Amanda E Drewicz, Justin Crevier, Eric Scott
Metadata Contact :: Jeffrey S Pigati
Publisher :: U.S. Geological Survey
Distributor :: U.S. Geological Survey - ScienceBase
SDC Data Owner :: Geosciences and Environmental Change Science Center
USGS Mission Area :: Ecosystems

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DATA_RELEASE_metadata_TUSK_isotope_study.xml Original FGDC Metadata	View	19.81 KB	application/fgdc+xml
0_Data_Dictionary_TUSK_isotope_study.csv		7.04 KB	text/csv
1_Summary_of_isotopic_data_TUSK_isotope_study.csv		7.66 KB	text/csv
2a_Statistics_for_isotopic_data_TUSK_isotope_study.csv		750 Bytes	text/csv
2b_Calculated percent_C_4_plants_TUSK_isotope_study.csv		208 Bytes	text/csv
2c_t_test_statistics_for_isotopic_data_TUSK_isotope_study.csv		702 Bytes	text/csv
3_Modeled_percent_C_4_plants_TUSK_isotope_study.csv		4.11 KB	text/csv
4_Raw_isotopic_data_modern_TUSK_isotope_study.csv		7.13 KB	text/csv
5_Raw_isotopic_data_fossils_TUSK_isotope_study.csv		27.47 KB	text/csv
6_C4_plant_inventories_TUSK_isotope_study.csv		12.75 KB	text/csv

Related External Resources

Type: Related Primary Publication

Kohn, M.J., Springer, K.B., Pigati, J.S., Reynard, L.M., Drewicz, A.E., Crevier, J., and Scott, E., 2022, Seasonality of precipitation in the southwestern United States during the late Pleistocene inferred from stable isotopes in herbivore tooth enamel: Quaternary Science Reviews, v. 296, p. 107784, https://doi.org/10.1016/j.quascirev.2022.107784.	https://doi.org/10.1016/j.quascirev.2022.107784

Purpose

Stable isotope data from herbivore tooth enamel were used to reconstruct seasonality of precipitation in the southwestern U.S. during the late Pleistocene.

Data release for Seasonality of precipitation in the southwestern United States during the late Pleistocene inferred from stable isotopes in herbivore tooth enamel

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