Pollen, botanical macrofossils, chemical components and ancient DNA were studied in samples from the rumen of a frozen Yakutian bison ( Bison priscus ) that lived ca. 10,500 cal a BP. The dialkyl glycerol ether lipid archaeol (2,3‐di‐ O ‐phytanyl‐ sn ‐glycerol) was detected and is interpreted to have been derived from methanogenic Archaea in the rumen. This is the oldest reported occurrence of archaeol attributed to digestive...