UPDATED 14C CHRONOLOGIES FOR NORTH AMERICAN QUATERNARY MAMMAL LOCALITIES IN THE NEOTOMA PALEOECOLOGY DATABASE FOR COMMUNITY PALEOECOLOGY

Community paleoecology is a potentially powerful approach for understanding the stability of ecological communities during long-term climate shifts like the Pleistocene-Holocene transition, but it requires the capacity to accurately estimate species co-occurrences across space and time. The Neotoma Paleoecology Database (www.neotomadb.org) is an open paleodata resource that stores assemblage-level taxonomic, spatial, and temporal information associated with Quaternary fossil localities. However, the age ranges associated with many vertebrate fossil localities are outdated, dating from the FAUNMAP project in the early 2000s, and many are based on uncalibrated radiocarbon dates. These inaccuracies make it difficult to compare ecological patterns among sites and through time and to correlate fossil occurrences with paleoenvironmental proxies, limiting the scope of paleoecological inference. Here, we extend and update the radiocarbon-based age estimates in Neotoma for late Quaternary small mammal fossil collections in North America, and develop consistent and updated age inferences suitable for broad-scale paleoecological studies.

We have now produced calibrated radiocarbon chronologies for all small mammal collections in Neotoma from North America with accessible published radiocarbon dates. This effort has added calibrated radiocarbon dates and estimated chronologies for 1638 existing Neotoma collection units. We extended the geochronological coverage by adding a total of 2986 new dates, including 292 previously undated collection units. Radiocarbon dates were calibrated to IntCal20 in OxCal, and two chronologies were computed for each collection using Bayesian estimation: (1) maximum and minimum age boundaries for the collection as a whole and for each dated analysis unit, and (2) the median and 2-sigma boundaries of the event age distribution for each analysis unit. The resulting new chronologies cover significantly more sites and are based on many more dates than the chronologies previously available in Neotoma. In addition, they provide fossil assemblage age estimates in calendar years, facilitating integration with other paleoenvironmental proxies. We anticipate that these updates will be useful for a variety of applications in the field of community paleoecology.