UPDATED CHRONOLOGY OF THE CAMELOPS HESTERNUS SPECIMEN FROM THE COYOTE CANYON/SOUTH HILL-MAULDIN SITE, BENTON COUNTY, WASHINGTON

In a previous contribution (Adams et al. 2017) we argued, based on a single radiocarbon date of 21,010+/-70 BP (Beta), that a partial Camelops hesternus metatarsal from the Coyote Canyon South Hill-Mauldin Site had a suggested calibrated date of 25,370 calBP. With the acquisition of two further dates on this specimen we here update the initial calibrated date estimate by some -140 calBP years. Three samples for radiocarbon analysis were collected from this metatarsal, and submitted to the Beta Analytic, Inc. (Miami, FL), DirectAMS (Bothell, WA), NOSAMS, (Woods Hole, MA), where the collagen was extracted, gelatinized, and filtered prior to analysis. Data from these analyses were run through OxCal 4.3 © Bronk Ramsey 2019. The DirectAMS sample yielded a date of AMS 20,720+/-75 BP (D-AMS 016465). This suggests a calibrated age range of 24,840-25,200, [average 24,970] calBP (at 68% probability) for this camel, with a 95.4% probability that the actual date of the CCSH-M camel falls somewhere within the range of 24,600-25,270 [average 24,970] calBP. The Beta Analytic sample gave a date of IRMS AMS 21010+/-70 BP (Beta 45508), suggesting a calibrated age range of 25,260-25,470 [average 25,360] calBP (at 68% probability), and a range of 25,140-25,580 [average 25,360] calBP (at 95.4% probability). The NOSAMS analysis reported a date of NOSAMS 21,100+/-270 BP (NOSAMS CCSH 03), suggesting a calibrated age range of 25,160-25,740 [average 25,380] calBP (at 68% probability), and a range of 24,670-25,930 [average 25,380] calBP (at 95.4% probability). These results suggest a combined mean value of 20,890+/-51 BP, with a 95.4% probability that the actual calibrated date of the Coyote Canyon camel falls somewhere within the range of 25,020-25,450 calBP. [with a combined calibrated mean of 25,230 calBP]. This find remains significant as the first radiocarbon dated and geographically documented specimen of Camelops hesternus from the Late Glacial Maximum in the Horse Heaven Hills region of south central Washington State. This also makes this specimen one of the only confirmed records of Yesterdays Camel from the Columbia Plateau of western North America.