MIDDLE HOLOCENE FLORA AND FAUNA FROM A RINGTAIL (BASSARISCUS,CARNIVORA) DEN, WESTERN GRAND CANYON, ARIZONA

ABSTRACT:

Dietary remains recovered from Bassariscus (ringtail) midden deposits of middle Holocene age in the Weeping Cliffs, lower Grand Canyon, Arizona, indicate a diverse ringtail diet of plants and small vertebrates. Remains of fruits and seeds predominated among the plant parts, especially of hackberry, several cacti, and groundcherry. Highly fragment- ed remains of small vertebrates included anurans, lizards, snakes, bats, and rodents. Only one recovered vertebrate specimen exceeded 5 mm in length, necessitating meticulous morphological comparisons for taxonomic identifications, which were usually limited to generic level. Two radioisotopic dates on the middens range from ca. 7300 to 7900 cal yr BP. Vertebrate remains from the middens provide the first Quaternary records of amphibians (including Anaxyrus and Hyla/Dryophytes) and a bat (Nyctinomops macrotis) from the Grand Canyon. Rare, fragmentary specimens provide one of only two fossil records of Dipsosaurus in Arizona.