Crustacea (Branchiopoda) among Organic Remains from Mammoth Hair

摘要

The purpose of this study is to analyze the taxonomic composition of the branchiopod crustaceans (Crustacea: Branchiopoda) from the assemblage of animal and plant remains recovered from fossil mammoth hair found in the Allaikha River basin, Sakha Republic, Russian Federation. We studied the hair structure. AMS radiocarbon dating of both the hair itself and the remains demonstrated their different ages. We found different animal and plant remains in the hair taphocoenosis. The most diverse and numerous remains belong to branchiopod crustaceans: resting eggs and distal portions of the mandibles of Anostraca, distal portions of the mandibles of Notostraca, filtering limbs of some Anostraca or Daphniidae, ephippia of Daphnia (Daphnia) curvirostris, Daphnia (Ctenodaphnia) atkinsoni, and D. (C.) magna. No representatives of D. (Ctenodaphnia) now occur in northeastern Eurasia, but our findings of numerous ephippia in the fossil hair of two mammoths, one from the Allaikha River and the other, studied previously, from the Bol'shaya Chukochya River basin (see Kirillova et al., 2016), show that Daphnia (Ctenodaphnia) taxa occurred in the region at least in the past and were probably common and widely distributed there. The reasons for the extinction of Daphnia (Ctenodaphnia) in northeastern Eurasia require additional special study. We also emphasize the need for further studies of the morphology of ephippia, resting eggs, and mandibles of recent Branchiopoda, which would be essential for adequate identification of Pleistocene remains.