Holarctic Marmots as a factor of Biodiversity.
Rumiantsev V.Yu;, Nikol'skii A.A. & Brandler O.V. eds.,
Abstracts, 3d Conference on Marmots (Cheboksary, Russia, 25-30 August 1997),
Moscow ABF 1997, 216p., 37-38 (Russian), 136-137 (English)


THE FOUNDATION OF HOLOCENE REMNANTS OF MARMOTA BOBAC IN THE SEMI-DESERT ZONE OF THE NORTHERN COAST OF CASPIAN SEA


A.I. Dmitriev

The Nizhny Novgorod State Pedagogical University
Nizhny Novgorod, Russia


The representatives of tribe Marmotini are known from miocen period in Europe-Asia and Northern America. On territory former USSR the dying out kinds are unknown (Gromov, Baranova, 1981), and modern total seven kinds, refering to a Marmota species. Determining bones remnants (about 42 thousand) fine Mammalia, assembled at Caspian coast, we have found out fragments of an axial skull and bottom jaws steppe marmot (total 53 bones). To external attributes of the fossil and collagene method determining of geological age 42 bones were date early-average Holocen and 11 bones -late Holocen.

Fig. Locations of bones remnants Steppe marmot on the Northern coast of Caspian sea

° - locations, Volga-Ural semi-desert - 1 and far Ural's semi-desert - 2 paleocenose,
°°° - modern Southern border of areal steppe marmot

The bones remnants steppe marmot concern to subspecie Marmota bobac schaganensis, Bashanov 1930. This subspecie and at the moment meets from left banks of Volga, to steppe zone of Southern Ural and Northern Kazakhstan. The bones remnants are found to the south of modern border areal in a semi-desert zone betwen the Volga and the Ural rivers and far Ural (fig.). In early-average holocen steppe marmot was widespread to the south and entered structure steppe vital form Volga-Ural's semi-desert paleocenose. Its representatives here made 18.6%, and predominate in this time the semi-desert species - 68.8%, in structure of which entered Cytellus pygmaeus, Ellobius talpinus, Eolagurus luteus and others. The number steppe marmot was low (0.4 % from total bones of fine Mammalia), and dominated in structure steppe lifeform Lagurus lagurus (13.2 %) and Microtus socialis (3.7 %).The maximum distribution the steppe forms have received here in the beginning Holocen. This period was characterized by weather changing to being warmer and moisturising of the climate on the Northern coast of Caspian sea, presence significant going to steppe places and introduction here some mezofillen forms. To late Holocen steppe marmot disappears here.

The bones remnants steppe marmot in far Urals (fig.) had late holocen age. It entered structure of the steppe vital form far Ural's semi-desert paleocenoses. The share it made in time 19,9 %, and predominated semi-deserted species (75.9 %). Among the steppe species the leading part occupied Lagurus lagurus (13.7 %) and Microtus socialis (2.6 %). The number steppe marmot in far Ural's paleocenose made 0.1 %.

Thus, steppe marmot in Holocen was of races vast to the south of the modern border and entered structure the Volga-Ural's and the far Ural's semi-deserted paleocenoses. Its extinct on this territory was connected with aridisation of a climate and amplification antropogenic activity.


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