This paper presents 75 new radiocarbon dates based on late Quaternary mammal remains recovered from eastern Taimyr Peninsula and adjacent parts of the northern Siberian lowlands, Russian Federation, including specimens of woolly mammoth (Mammuthus primigenius), steppe bison (Bison priscus), muskox (Ovibos moschatus), moose (Alces alces), reindeer (Rangifer tarandus), horse (Equus caballus) and wolf (Canis lupus). New evidence permits reanalysis of megafaunal extinction dynamics in the Asian high Arctic periphery. Increasingly, radiometric records of individual species show evidence of a gap at or near the Pleistocene/Holocene boundary (PHB). In the past, the PHB gap was regarded as significant only when actually terminal, i.e., when it marked the apparent ''last'' occurrence of a species (e.g., current ''last'' occurrence date for woolly mammoth in mainland Eurasia is 9600 yr ). However, for high Arctic populations of horses and muskoxen the gap marks an interruption rather than extinction, because their radiocarbon records resume, nearly simultaneously, much later in the Holocene. Taphonomic effects, C 14 flux, and biased sampling are unlikely explanations for these hiatuses. A possible explanation is that the gap is the signature of an event, of unknown nature, that prompted the nearly simultaneous crash of many megafaunal populations in the high Arctic and possibly elsewhere in Eurasia.

New finds of the fossil brown bear (Ursus arctos L., 1758) remains from the territory of Yakutia have been investigated: skulls and mandibular bones. The new finds are of exceptionally large sizes, most of their measurements far exceed those of not only the modern brown bear from Yakutia, but also the maximum values of the largest representatives of modern subspecies from Eurasia, U. a. beringianus and U. a. piscator. Analysis of various data indicates that the giant brown bear existed in the north of Yakutia during the Karginian interstadial of the Late Pleistocene.