Figure 4

(a) Photograph of Alaskan bison skull A-501-1027 (Bison priscus) from the AMNH collection recovered at Fairbanks Creek in 1949. The skull has been dated at 18,635 ± 105 CAL yr B.P. (Table S1). (b,c) SEM images of two microspherules magnetically separated from fine-grained sediment contained within the skull.