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The micromammal fauna of the Dnieper modern channel alluvium: taphonomic and biostratigraphic implications [ La faune des petits mammifères des alluvions du lit fluvial actuel du Dniepr : implications taphonomiques et biostratigraphiques.] - article ; n°1 ; vol.15, pg 233-242

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Quaternaire - Année 2004 - Volume 15 - Numéro 1 - Pages 233-242
An analysis of small mammal remains from the modern channel alluvium of the Dnieper River is presented. The taphocoenosis (death assemblage) is mixed, i.e. it contains remains of different geological age. Micromammahan analysis has accordingly been undertaken separately for the different age groups. The relative ages of these groups have been estimated on the basis of the degree of bone fossilisation observed. Three stages of fossilisation were distinguished If, IIf and IIIf in order of increasing degree of fossilisation.The relative ages of the differently fossilised groups have been further confirmed by morphometrical and morphotypical data Using the evolutionary level of the voles present within the samples, their geological ages have been established as Eemian and Early Weichsehan (Illf), Middle and Late Weichsehan (Ilf) and Holocene (If).
The sedimentary body in which the remains are contained (the channel alluvium of the Dnieper river modern floodplain) is known to have been formed during the Holocene. However, the main part of matenal is attributable to the Late Pleistocene (IIIlf and IIf), suggesting reworking from the older deposits of the Second and First terraces above the modern floodplain. This formation process is probably typical for the majority of mixed alluvial taphocoenoses In these assemblages, even if only a few remains are of advanced morphology and seem to be of younger geological age and most of the remains are of archaic aspect, it is the age of the youngest elements of the mixed fauna that reflect the age of the alluvium whereas the more archaic (older) remains should be considered as redeposited.
The taphocoenosis under investigation turned out to be especially suitable matenal for the study of morphotypical variability because of the abundance of voles remains. Analysis of water vole remains from the Dnieper modern alluvium and of Holocene Arvicola terrestris from different climatic zones of Eastern Europe has shown that the morphotypical composition of species populations can fluctuate according to different environmental conditions. This phenomenon can lead to biostratigraphical misinterpretations of morphotypical data if the significant periodical climatic changes that occurred during the Pleistocene are not taken properly into account.
Cet article présente une étude des restes des petits mammifères des alluvions du lit fluvial actuel du Dniepr. L'obtention d'une information pertinente à partir de cette taphocénose mixte est rendue possible grâce à l'existence d'une relation entre le degré de fossilisation des os et leur âge géologique relatif. II existe ainsi trois stades de fossilisation selon l'âge géologique des restes. Les âges des groupes de fossiles déterminés sur la base des indices du niveau d'évolution des Arvicolidés sont rapportés à l'Eémien et au Weichselien ancien, au Weichselien moyen et récent et à l'Holocène. Quoique les fossiles holocènes soient les plus proches de la période de formation des alluvions, les fossiles les plus anciens (première moitié du Pléistocène supérieur) dominent dans la structure de cette taphocénose. Il est évident qu'ils ont été redéposés dans l'actuelle plaine d'inondation à partir de terrasses du Pléistocène récent (Ie, IIe, et peut-être IIIe). Cela permet d'espérer trouver de petits mammifères dans les dépôts de ces terrasses qui jusqu'à présent n'ont pratiquement pas fourni de caractérisation microthériologique. II est à supposer que la composition des associations et les mécanismes de leur formation sont communs à la plupart des taphocénoses mixtes. Ainsi dans leur étude il faut attacher une grande attention à la partie la plus jeune de l'ensemble général des fossiles, la plus avancée du point de vue d'évolution. C'est elle qui sera synchrone au moment de la formation de la séquence alluviale , les fossiles plus anciens seront considérés comme redéposés même s'ils dominent quantitativement.
En outre, l'analyse morphotypique des fossiles de Arvicola terrestris de la taphocénose des alluvions actuelles du Dniepr et l'étude des Arvicola récents des diverses zones climatiques de l'Europe orientale démontrent la possibilité de certaines fluctuations des indices du niveau d'évolution chez les Arvicolidae sous l'influence des changements de l'environnement. Ce phénomène doit ainsi influer sérieusement sur la précision de la date des sédiments, sur la base des indices du niveau d'évolution des Arvicolidae.
10 pages
Source : Persée ; Ministère de la jeunesse, de l’éducation nationale et de la recherche, Direction de l’enseignement supérieur, Sous-direction des bibliothèques et de la documentation.

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Publié le 01 janvier 2004
Nombre de lectures 27
Langue English
Poids de l'ouvrage 2 Mo

L.V Popova
The micromammal fauna of the Dnieper modern channel
alluvium: taphonomic and biostratigraphic implications [ La faune
des petits mammifères des alluvions du lit fluvial actuel du
Dniepr : implications taphonomiques et biostratigraphiques.]
In: Quaternaire - Volume 15 - Numéro 1-2 - 2004. pp. 233-242.
Citer ce document / Cite this document :
Popova L.V. The micromammal fauna of the Dnieper modern channel alluvium: taphonomic and biostratigraphic implications [
La faune des petits mammifères des alluvions du lit fluvial actuel du Dniepr : implications taphonomiques et
biostratigraphiques.]. In: Quaternaire - Volume 15 - Numéro 1-2 - 2004. pp. 233-242.
doi : 10.3406/quate.2004.1770
http://www.persee.fr/web/revues/home/prescript/article/quate_1142-2904_2004_num_15_1_1770Abstract
An analysis of small mammal remains from the modern channel alluvium of the Dnieper River is
presented. The taphocoenosis (death assemblage) is mixed, i.e. it contains remains of different
geological age. Micromammahan analysis has accordingly been undertaken separately for the
age groups. The relative ages of these groups have been estimated on the basis of the degree of bone
fossilisation observed. Three stages of fossilisation were distinguished If, IIf and IIIf in order of
increasing degree of fossilisation.The relative ages of the differently fossilised groups have been further
confirmed by morphometrical and morphotypical data Using the evolutionary level of the voles present
within the samples, their geological ages have been established as Eemian and Early Weichsehan (Illf),
Middle and Late Weichsehan (Ilf) and Holocene (If).
The sedimentary body in which the remains are contained (the channel alluvium of the Dnieper river
modern floodplain) is known to have been formed during the Holocene. However, the main part of
matenal is attributable to the Late Pleistocene (IIIlf and IIf), suggesting reworking from the older deposits
of the Second and First terraces above the modern floodplain. This formation process is probably typical
for the majority of mixed alluvial taphocoenoses In these assemblages, even if only a few remains are of
advanced morphology and seem to be of younger geological age and most of the are of
archaic aspect, it is the age of the youngest elements of the mixed fauna that reflect the age of the
alluvium whereas the more archaic (older) remains should be considered as redeposited.
The taphocoenosis under investigation turned out to be especially suitable matenal for the study of
morphotypical variability because of the abundance of voles remains. Analysis of water vole remains
from the Dnieper modern alluvium and of Holocene Arvicola terrestris from different climatic zones of
Eastern Europe has shown that the morphotypical composition of species populations can fluctuate
according to different environmental conditions. This phenomenon can lead to biostratigraphical
misinterpretations of morphotypical data if the significant periodical climatic changes that occurred
during the Pleistocene are not taken properly into account.
Résumé
Cet article présente une étude des restes des petits mammifères des alluvions du lit fluvial actuel du
Dniepr. L'obtention d'une information pertinente à partir de cette taphocénose mixte est rendue possible
grâce à l'existence d'une relation entre le degré de fossilisation des os et leur âge géologique relatif. II
existe ainsi trois stades de fossilisation selon l'âge géologique des restes. Les âges des groupes de
fossiles déterminés sur la base des indices du niveau d'évolution des Arvicolidés sont rapportés à
l'Eémien et au Weichselien ancien, au Weichselien moyen et récent et à l'Holocène. Quoique les
fossiles holocènes soient les plus proches de la période de formation des alluvions, les fossiles les plus
anciens (première moitié du Pléistocène supérieur) dominent dans la structure de cette taphocénose. Il
est évident qu'ils ont été redéposés dans l'actuelle plaine d'inondation à partir de terrasses du
Pléistocène récent (Ie, IIe, et peut-être IIIe). Cela permet d'espérer trouver de petits mammifères dans
les dépôts de ces terrasses qui jusqu'à présent n'ont pratiquement pas fourni de caractérisation
microthériologique. II est à supposer que la composition des associations et les mécanismes de leur
formation sont communs à la plupart des taphocénoses mixtes. Ainsi dans leur étude il faut attacher
une grande attention à la partie la plus jeune de l'ensemble général des fossiles, la plus avancée du
point de vue d'évolution. C'est elle qui sera synchrone au moment de la formation de la séquence
alluviale , les fossiles plus anciens seront considérés comme redéposés même s'ils dominent
quantitativement.
En outre, l'analyse morphotypique des fossiles de Arvicola terrestris de la taphocénose des alluvions
actuelles du Dniepr et l'étude des Arvicola récents des diverses zones climatiques de l'Europe orientale
démontrent la possibilité de certaines fluctuations des indices du niveau d'évolution chez les Arvicolidae
sous l'influence des changements de l'environnement. Ce phénomène doit ainsi influer sérieusement
sur la précision de la date des sédiments, sur la base des indices du niveau d'évolution des Arvicolidae.15, (1-2), 2004, p 233-242 Quaternaire,
THE MICROMAMMAL FAUNA
OF THE DNIEPER MODERN CHANNEL ALLUVIUM:
TAPHONOMIC AND BIOSTRATIGRAPHIC IMPLICATIONS
L. V. POPOVA*
ABSTRACT
An analysis of small mammal remains from the modern channel alluvium of the Dnieper River is presented The taphocoenosis (death assem
blage) is mixed, i.e. it contains remains of different geological age. Micromammahan analysis has accordingly been undertaken separately for the
different age groups. The relative ages of these groups have been estimated on the basis of the degree of bone fossilisation observed. Three stages of
fossilisation were distinguished If, Ilf and Illf in order of increasing degree of fossilisation The relative ages of the differently fossilised groups have
been further confirmed by morphometncal and morphotypical data Using the evolutionary level of the voles present within the samples, their geological
ages have been established as Eemian and Early Weichsehan (Illf), Middle and Late Weichsehan (Ilf) and Holocene (If).
The sedimentary body in which the remains are contained (the channel alluvium of the Dnieper river modern floodplain) is known to have been
formed during the Holocene However, the main part of matenal is attributable to the Late Pleistocene (Illf and Ilf), suggesting reworking from the older
deposits of the Second and First terraces above the modern floodplain This formation process is probably typical for the majority of mixed alluvial
taphocoenoses In these assemblages, even if only a few remains are of advanced morphology and seem to be of younger geological age and most of
the remains are of archaic aspect, it is the age of the youngest elements of the mixed fauna that reflect the age of the alluvium whereas the more archaic
(older) remains should be considered as redeposited
The taphocoenosis under investigation turned out to be especially suitable matenal for the study of morphotypical variability because of the
abundance of voles remains. Analysis of water vole remains from the Dnieper modern alluvium and of Holocene Arvicola terrestns from different cl
imatic zones of Eastern Europe has shown that the morphotypical composition of species populations can fluctuate according to different environmental
conditions This phenomenon can lead to biostratigraphical misinterpretations of morphotypical data if the significant periodical climatic changes that
occurred during the Pleistocene are not taken properly into account
Key-words: Small mammals, modern channel alluvium, degree of fossilisation, Late Pleistocene, evolutionary level, environmental conditions.
RÉSUMÉ
LA FAUNE DES PETITS MAMMIFÈRES DES ALLUVIONS DU LIT FLUVIAL ACTUEL DU DNIEPR : IMPLICATIONS TAPHONOMIQUES
ET BIOSTRATIGRAPHIQUES
Cet article présente une étude des restes des petits mammifères des alluvions du ht fluvial actuel du Dniepr. L'obtention d'une information perti
nente à partir de cette taphocénose mixte est rendue possible grâce à l'existence d'une relation entre le degré de fossilisation des os et leur âge géologique
relatif II existe ainsi trois stades de fossilisation selon l'âge géologique des restes. Les âges des groupes de fossiles déterminés sur la base des indices
du niveau d'évolution des Arvicohdés sont rapportés à l'Eémien et au Weichselien ancien, au Weichsehen moyen et récent et à l'Holocène Quoique
les fossiles holocènes soient les plus proches de la période de formation des alluvions, les fossiles les plus anciens (première moitié du Pleistocene
supérieur) dominent dans la structure de cette taphocénose. Il est évident qu'ils ont été redéposés dans l'actuelle plaine d'inondation à partir de terrasses
du Pleistocene récent (le, Ile, et peut-être Ille) Cela permet d'espérer trouver de petits mammifères dans les dépôts de ces terrasses qui jusqu'à présent
n'ont pratiquement pas fourni de caracténsation microthenologique II est à supposer que la composition des associations et les mécanismes de leur
formation sont communs à la plupart des taphocénoses mixtes. Ainsi dans leur étude il faut attacher une grande attention à la partie la plus jeune de
l'ensemble général des fossiles, la plus avancée du point de vue d'évolution C'est elle qui sera synchrone au moment de la formation de la séquence
alluviale , les fossiles plus anciens seront considérés comme redéposés même s'ils dominent quantitativement.
En outre, l'analyse morphotypique des fossiles de Arvicola terrestris de la taphocénose des alluvions actuelles du Dniepr et l'étude des Arvicola
récents des diverses zones climatiques de l'Europe orientale démontrent la possibilité de certaines fluctuations des indices du niveau d'évolution chez
les Arvicohdae sous l'influence des changements de l'environnement Ce phénomène doit ainsi influer sérieusement sur la précision de la date des
sédiments, sur la base des indices du niveau d'évolution des Arvicohdae.
Mots-clés : Micromammifères, alluvions, lit fluvial actuel, degré de fossilisation, Pleistocene supérieur, niveau d'évolution.
* National Taras Shevchenko University ofKyiv, geological faculty, Vasilkovskaja Street, 90, KIEV, Ukraine, 03022, tel 259-70-26,
e-mail spopov@umv kiev ua
Manuscrit reçu le 13/12/2002, accepté le 06/01/2004 I
234
and faunistical changes in time (ql for Arvicola terres- INTRODUCTION
tris, q2 for other Arvicolidae, q3 for other small mamm
Pleistocene alluvial sediments are often rich in the als, details in the text).
remains of small mammals, many of which are well
I - THE AGE OF THE TAPHOCOENOSIS known for their rapid rates of evolution and for the dis
tinctive morphological trends that are apparent throu AND ITS FORMATION PROCESS:
ghout their stratigraphical range. These trends allow the ANALYSIS OF TAPHONOMICAL FACTORS
use of micromammalian morphological data for age cali
bration. In addition, changes in the composition of small A historical perspective on the study of hetero-
mammal assemblages often reflect climatic events, which chronous (mixed) taphocoenoses in Eastern Europe.
are also an important element of Pleistocene stratigraphy. The presence of small mammal remains in the Dnieper
However, it is necessary to take into account a) the even Late Pleistocene terraces (two or three such terraces may
tual reworking of remains during the formation of allu be identified above the modern floodplain in the Middle
vial suites; and b) the possibility that key morphological Dnieper area, according to Schelcoplias et al. (1986))
features, which may have a bearing on the age of the was almost completely unknown until recently. The Late
fauna, have fluctuated under the influence of changing Pleistocene mammal fauna had been collected on the
environmental conditions. The resolution of these two point bar beaches of the Dnieper River only. This fauna
questions begins by studying the youngest geological provides unique information concerning the Pleisto
body of alluvial origin, i. e. of a modern flood plain. cene of Dnieper area. It has been discussed in the litera
This can be regarded as a basis for the improvement ture since the 1950th (Pidoplichko, 1957; Topachevsky,
of methods used in the research of alluvial formations, 1961; Topachevsky et al, 2000). The source of the
including small mammal analysis, as in the present case. mammal remains in the Dnieper River point bar bea
The taphocoenosis under investigation (channel alluvium of ches is considered to be its modern channel alluvium
the recent Dnieper flood plain, fig. 1) contains remains of diffe (Topachevsky, 1961).
rent geological age, as demonstrated by Topachevsky (1961). The study of such heterochronous material required
The purpose of the present paper is to study the fo specific approaches, which are grounded on the cor
rmation of alluvial deposits by examining the taphocoenos respondence between the observable degree of fos
is of the Dnieper River modern channel alluvium and to silisation of the remains and their age (Gromov, 1957;
analyse the influence of environmental changes on indi Pidoplicko, 1957; Topachevsky, 1961). In his research
ces of small mammal evolutionary level. The paper cons into the Pleistocene small mammal fauna of the Don
River point bar beaches, Gromov assessed the degree of ists of two parts, the first dealing with taphonomy and
the second with the morphological variability of palaeo- fossilisation of a specimen by the difference in colour
populations. They differ in the methods used, as well as between the jaw bone, dentine and enamel of the teeth
in the material involved. However, they are interlinked (Gromov, 1957). Bone matter acquires colour first, then
because they represent two aspects of the same dataset, dentine and then enamel, the last being the hardest mater
ial in the mammal skeleton, which retains its organic providing a means of overcoming some of the difficulties
of the biostratigraphical interpretation of micromammal matter longest and acquires staining from surrounding
ian data. sediments most slowly.
The list of abbreviations used is: Illf, Ilf and If - fos The relative age sequence of the remains is therefore as
silisation groups from the oldest remains (Illf) to the follows, from youngest to oldest: (1) remains where the
youngest ones (If). 2); ELI - evolutionary level indeces jaw is stained but the teeth are only lightly-tinted or not
(for voles); ql, q2, q3 - samples, analysed separately for tinted; (2) remains where the jaw and dentine are stained
more precise estimation of fauna's evolutionary advance the same colour and (3) remains where the jaw, dentine
and enamel are stained to the same degree. These stages
were described as fossilisation groups I-III by Gromov
- the area of investigation (1957), hereafter named If, Ilf, and Illf (fig. 2).
There are also some additional criteria for estimating
the degree of fossilisation. For example, bone that is
more susceptible to staining can equally lose staining
faster under the influence of weathering or other effects.
It should be emphasised that both the colour of the fos
silised remains and its intensity depend on environmental
conditions. Remains with a black and/or grey colour are
more common in the Dnieper Middle Reaches, whereas
remains of yellowish to brown colour are prevalent in the
Lowest Reaches. This difference in colour is a result of
the higher content of humic acids in the water of the UKRAINE , 500 km , Middle Dnieper, owing to the richer arboreal vegetation
in the area. However, the relative age of the remains is
estimated by the difference in colouration of the dentine, Fig. 1: The area of investigation.
Fig 1 Région étudiée. enamel and bone and not by the colour itself or its intensity. 235
Fig. 2: Main fossilisation stages of remains (If, Ilf, Illf- fossilisation groups).
Fig 2 Stades de des restes (Illf Ilf If- groupes de fossilisation)
Methods. To carry out the analysis of the small This method was applied to the mixed fauna of the
mammal fauna from the Dnieper modern alluvium it is modern Dnieper flood plain by Topachevsky (1961). The
necessary to subdivide the samples according to their georelative age of the fossilisation stages of the aforement
logical age, in accordance with Gromov (1957). Howevioned assemblage have been proved using the collagen
er, the fauna investigated may be divided not only on method proposed by Pidoplichko (1957). The
the basis of their geological age but also by the following involves the calcination of fossil bone to remove
characters: organic matter. The more weight the bone loses, the more
1. Number of diagnostic skeletal elements present. organic material (collagen) has not replaced by minerals,
Most of the voles have a single diagnostic element in and consequently, the younger the remains are. These
each side of their jaws - the first lower molar (M,). In data are then compared with the results of calcination of
contrast, in jerboas, for example, not only are all the teeth bones from localities of known geological age (mostly
diagnostic but so are the postcranial bones. These last Palaeolithic sites), thereby enabling the geological age of
haven't been taken into account during the course of this the locality under investigation to be established.
investigation because the fossilisation stage of non-dentHowever, during such age estimation, it is necessary to
al material cannot be established. However, the number take into account different rates of fossilisation because
of diagnostic teeth in different families also varies signiof the physical and chemical properties of environment
ficantly (e.g. hamsters have four times more diagnostic (Gromov, 1957). Direct comparison of the degree of fos
teeth then voles) and this might misrepresent the real silisation, which is estimated for localities of different
taxonomic quantitative composition. genesis, as the base of geological dating (Pidoplichko,
2. Differential representation of taxa: ecological and 1957) is questionable. In addition, when the assemblage
taphonomic influences. The dominance of water vole under investigation is relatively old and all organic matter
remains in the assemblages is very strongly pronounced had been replaced, both methods mentioned (Gromov,
(70 % of all remains from the assemblage). Arvicola is a 1957; Pidoplichko, 1957) are inapplicable.
flood-plain dweller, living in close proximity to the river, Material. Remains were collected in the 1950s by
and therefore has the highest probability of becoming members of the department of Paleozoology (Shmalgau-
incorporated in the alluvial deposits. zen's Institute of Zoology, Kiev) under the supervision
3. The biostratigraphic importance of different taxa is of V. A. Topachevsky from the subfacies of point bar
not restricted to species appearance and extinction. These beaches of the modern channel alluvium of the Dnieper
events were rare through the Late Pleistocene because it Middle Reaches (from Kiev to Mishurin Rih village,
was relatively short span of time and most of the Late Dnepropetrovsk' region). The remains are represented
Pleistocene small mammal species encountered are still mainly by jaws and isolated teeth. An inventory of small
extant. The time-transgressive trends of directional mormammal species from the Dnieper Holocene alluvium
phological changes observed in many lineages of Roden- (Middle Reaches) was provided by Topachevsky et al.
tia are a more reliable basis for Late Pleistocene bio- (2000) with some author's changes (the number of iden
stratigraphy. Morphological features, which characterised tifiable specimens is in brackets):
by such trends (called hereinafter evolutionary level indiErinaceus europaeus (5), Talpa europaea ill), Des-
ces or ELI) are therefore used as biostratigraphic criteria. mana moschata (37), Sorex araneus (5), Neomys fodiens
These indices can be available for a whole genus or sever(2), Crocidura suaveolens (1), Crocidura leucodon (1),
al genera and are informative over significant spans of Lepus europaeus (45), L. tanaiticus (82), Ochotona
time. But some of ELI lost their stratigraphical signifpusilla (28), O. spelaeus (7), Sciurus cf. vulgaris (2),
icance with time (for example, degree of root reduction in Marmota bobac (46), Spermophilus superciliosus fulvoi-
many recent arvicolids) (Maul et al, 1998). des (5), S. major (79), S. suslicus abbreviates (142),
In the present work, the relative length of the anteroco- Castor fiber (4), Alactaga major (35), Alactagulus pumi-
nid complex (A/L), the enamel differentiation ratio (SDQ) lio (2), Stilodipus telum (1), Spalax microphtalmus (79),
and the morphotypical variability of palaeopopulations are Rattus rattus (1), Sylvcemus sp.(36), Muridae gen. et
used as the most important indices, which allow the estsp. (43), Cricetus cricetus (124), Cricetulus migratorius
imation of the age of fossilisation groups. A/L expresses (3), Ellobius talpinus palaeoucrainicus (18), Clethriono-
the length of anteroconid complex of the first lower molar mys glareolus (15), Lagurus lagurus major (34), Eolagu-
(M,) as a percentage of the total (maximal) occlusal length rus luteus antecedens (16), Dicrostonyx cf. gulielmi (6),
of the tooth, as defined by Van der Meulen (1973), and is Arvicola terrestris (1479), Microtus gregalis kriogenicus
applicable for all Late Pleistocene Arvicolidae. The SDQ (44), M. oeconomus major (138), M. cf. arvalis (43), M.
was devised by Heinrich (1978) for Arvicola and Mimomys agrestis (17), Microtus sp. (15). 236
savini. It provides a measurement of the relative thi mation of a fauna's evolutionary level, although they are
ckness of the enamel of the posterior cutting edges in the useful for other aspects of faunal analysis.
salient triangles of the Mj as a percentage of the corre Therefore, all representatives of the fauna researched
sponding anterior cutting edges. Morphotypical analysis can be arranged in the following descending sequence, in
concerns changes in the shape of the anteroconid. An accordance with their biostratigraphical importance: A.
terrestris - other arvicolids - other small mammals. individual morphotype can be defined as possessing a
distinctive pattern in this structure and it does not matter 4. Fossilisation rate. It must be noted that remains
for the purposes of a biostratigraphical study if each pat having all the colour peculiarities of the Illf, as stated
tern is discontinuous in any sense (discontinuity can be by Gromov (with completely darkened molar enamel)
caused by morphological, hereditary or functional fac occurred only among the Arvicolidae1. Other families
tors, which may differ according to taxon) or if inte were placed by us in the Illf group if they had incisors
rmediate forms exist. A qualitative approach to the study with enamel darker then bone or if they were samples
of shape variability is more convenient and more useful lacking incisors but of well-fossilised appearance, with
than measuring of entrant and re-entrant angles, which substantially coloured enamel on the molars. In this a
sometimes used for anteroconid shape describing. way, the speed of the fossilisation process and its outward
New schemes for analysing morphotypical variability effects can be slightly different for different taxa. Theref
in Arvicola and Microtus oeconomus are proposed in ore, the fossilisation groups for taxa cannot be
the present paper. Other species have been analysed by considered as of exactly the same age.
Rekovets(1994). All the aforementioned factors should be taken into
In other small mammal species, only appearance and account in the course of micromammalian analysis.
disappearance events can be used, and these were caused Before dividing all remains into the three fossilisation
mostly by climatic changes through the Late Pleistocene. groups, the samples were split into groups with approxi
These taxa are therefore not able to contribute to the mately similar numbers of diagnostic elements, percen-
0,8%
s
e e
o
o e
i m
es
«g
23% 4» a «A
m a. 4) W
1
2
Fig. 3: Schemes of morphological differentiation of M, for Microtus s o oeconomus (I), and for Arvicola (II).
Arrow shows main direction of chronoclinal variation, percentage
of each morphotype is shown in Illf, Ilf and If in M. oeconomus,
light-colored morphotypes in Arvicola - ancient structure of Pleisto
cene water voles, dark-colored morphotypes - typical for
modern water voles, those with dark background - senile morphotypes, with light background - juvenile morphotypes. Temporal dynamics of
Arvicola morphotypical composition has been presented also on fig. 4 with more details.
Fig 3 ■ Schéma de la différenciation morphologique de Ml chez Microtus oeconomus (I) et Arvicola (II) La flèche indique la direction principale de
la variation chronoclinale, le pourcentage de chaque morphotype est montré dans Illf, Ilfet If pour M oeconomus Les morphotypes faiblement colorés d' Arvicola représentent l'ancienne structure dentaire des campagnols aquatiques pleistocenes, les morphotypes foncés, typiques des campagnols
aquatiques modernes, les morphotypes senties sont entourés d'un fond gris foncé, et les morphotypes juvéniles d'un fond gris clair Les dynamiques
temporelles de la composition des morphotypes d' Arvicola sont présentées aussi dans la fig 4 avec plus de détails 237
Small mammal localities Recent channel alluvium of Middle Dnieper (upper index - average SDQ mean)
Eastern Europe complex[19] 1994)
(Agajanyian & terraces link SDQ Glushancova, 1986; or(Rekovets, Western Europe Small mammals assemblage (2q) (min, Markova, 1982; (Heinrich, 1982; Mikhailescu & (dominated taxa designated by display type) mean, Dnieper Mauled/., 1998) Faunal a. Markova, 1992; max)
2 Rekovets, 1985b;
<♦!« 1994)
Holocene M. cf. arvalfs, M. oeconomus, M. agrestis, 57,1 flood Ellobius talpinus, Clethrionomys. glareolus, -75,6- - - recent I plain Spalax microphtalmus, Cricetus cricetus, S. 83,3 suslicus, Muridae
M. oeconomus, M. gregalis, L. lagurus, M. Euerwager
Mezhyrych61, ciarvalis, E. luteus, D. guilielmi, M. Novgorod- Plisszanto84'48 Buchl83'03, 64,3 Late Paleol agrestis, C. glareolus, S. microphtalmus, C. -80,7- I II Seversky83>6Troitsa cricetus, S. suslicus, S. major, S. Kemathenhohle II80 Pleistocene 114,3 ithic superciliosus, Muridae, L. tanaiticus, L. 89'23; 89,54 Istallosko Hotylevo-2 europaeus, 0. pusilla, 0. spelaeus
Bulhary 93'31 M. oeconomus, M. gregalis, L. lagurus, M. Molodove- 1, cf. arvalis, M. agrestis, C. glareolus, E. Burgtonna299'7 Subaliuk 96'4, Late Hotylevo- 1, 66,7 luteus, D. guilielmi, Ellob. talpinus, C. Shkurla- Novonekrasovka: -92,3- II III cricetus, Spermophilus major, S. supercil upper layer 86'82, Taubach105'15 tovsky 125 iosus, S. suslicus, Muridae, Sciurus lower layer 92'4, vulgaris, Lepus europaeus, L. tanaiticus, Mikhailovka-5 Ochotona pusilla, 0. spelaeus
Tab. 1: The place of micromammalian associations from recent Dnieper channel alluvium in succession of the Late Pleistocene and Holocene
faunas of Europe.
Tab 1 Place des associations microthériologiques des alluvions actuelles du Dniepr dans la des faunes européennes du Pleistocene
supérieur et de l 'Holocene
tage of taxa representatives, biostratigraphic importance, localities with a similar faunal composition and evolu
and fossilisation rate. Thus three groups named herei tionary level, whose place within the biostratigraphical
nafter q-groups (samples for quantitative analysis)2 have framework is known. Faunas that have a similar evolutio
been obtained: nary level are considered to be similar in age. This stage
A. terrestris - lq, other arvicolids - 2q, other small of developing work in micromammalian material from
mammals - 3q. the modern channel alluvium of the Dnieper River has
The dynamics of faunal composition in time (from Illf to been previously presented in detail (Popova, 2000), and
If) have been studied on 2q and 3q material, and changes of the table 1 provides the data for only one of the most
evolutionary level indices have been studied on remains of important indices of the fauna's evolutionary level - the
lq and 2q. This is of necessity a relatively coarse approach rate of Arvicola enamel differentiation (SDQ).
but any attempt to consider all the aforementioned factors The geological age of remains attributed to Illf lies
in every single small mammal family would lead to excessi between the interval that starts with the fauna from
vely small samples that are unfit for analysis. Novonekrasovka (Lower Reaches of the Danube River)
Results. ELI analysis proves the temporal succession (Mikhailesku and Markova, 1 992) and ends with Molo
of the fossilisation groups, which was noted earlier (Topa- dove- 1 (Agadzhanyian, 1982) - (a Palaeolithic site on
chevsky, 1961) (IIIf->IIf->If from oldest to youngest). the Southern Bug River). In a stratigraphical framework
Remains attributed to Illf, compared to Ilf and If, are (Bogutsky et al, 2001), this period corresponds with
characterised by the presence of archaic features. They the Kaydatsky, Prilutsky and Udaisky horizons, or with
lack the most differentiated morphotypes and present the Eemian interglacial and Early Weichselian. Small
simple forms in morphotypical composition, which is mammal remains assigned to Illf are here considered
unusual for more recent faunal representatives (fig. 3). to fit within the Skurlatovsky (early Late Pleistocene)
The water vole's enamel differentiation is of Microtus faunal complex, in contrast to the Middle Pleistocene
type but is not yet pronounced (tab. 1). The relative length age attributed by Pidoplichko (1957) and Topachevsky
of anteroconid is, as a rule, less in Illf than in representat (1961). Ilf includes remains of the Late Palaeolithic
ives of Ilf and If. Remains of Ilf and, even more, If look complex, and generally corresponds with the Valdai
more advanced. (Weichselian) glaciation from the same framework
A search for analogues for every fossilisation group (Bogutsky et al, 2001). The age of If remains is
in situ is the next stage of analysis. These analogues are Holocene (Popova, 2000).
21 Although The pnncipal remains idea m of which such dividing enamel earlier of incisors suggested is more by intensively Maleeva (1983). coloured than bone occur in other families. 238
DISCUSSION alluvium of the Dnieper River, having been reworked from
older and higher alluvial suites of the First and Second ter
The issue of from where the remains have been derived races above the flood plain. This should be regarded as the
is still without an explanation as small mammal locali fairly often event when taphocoenoses are formed in alluvial
ties are unknown in the Late Pleistocene Dnieper alluvial conditions, hi consequence, mixed (heterochronous)
deposits in the vicinity. Small mammal remains of Late taphocoenoses in most cases will comprise redeposited older
Pleistocene age have been found only in alluvial deposits fauna together with remains that are coeval with the alluvial
of the First terrace of the river Sula (Dnieper's left tribu body that contains them. Furthermore, as has been demonst
tary) - (Markova, 1982). The loess-soil cover of the pla rated in the present study, reworked older remains can make
teaux and terraces above the flood plain are unlikely to up the greatest part of the assemblage.
have yielded such rich micromammal material because
II - ENVIRONMENTAL INFLUENCE ON VALUES of low occurrence of remains in these deposits. Moreov
er, the remains found in loessic deposits are very fra OF INDICES OF SMALL MAMMAL EVOLUTIO
gile and would be easily destroyed if transported. Thus, NARY LEVEL
the remains found on point bar beaches are considered to
be reworked from the modern channel Dnieper alluvium The geological age of the assemblages from the Dnieper
according to Gromov (1957) and Topachevsky (1961). River alluvium has been based on the ELI estimation in the
Other significant evidence of the aforementioned sug Arvicolidae, according to their fossilisation groups. Howe
gestion seems to be the finding of some small mammal ver, there exists undoubted evidence that some ELI in
remains (Arvicolidae gen., Spermophilus sp.) in sands that Pleistocene small mammals (for example, skull size, which,
have been used in the construction of refinery buildings, as a rule, increases over time - (Rekovets, 1985b) fluctuate
located 4 km south of Pekari village, in the Kaniv region. according to climate change. It is possible that some other
These sands were dredged from modern channel all biostratigraphically important features of arvicolids morphol
uvium deposits and have yielded small mammal remains ogy are effected by environmental conditions too, because,
similar to those from the point bar beaches in terms of as it had been shown for recent Myomorpha (Zagorodniuk
and Kavun, 2000), formation of morphological differences their colouring peculiarities. Thus, remains of Late Pleis
tocene age have become mixed with Holocene ones in the between close related species in many cases has been based
on the delay of ontogenetic development and on the later hereHolocene channel alluvium of the Dnieper, from where
ditary fixation of juvenile traits in the definitive state. Ontogenthey have been derived into the beach deposits.
etic changes are displayed as body size increase (especially The Late Pleistocene age of remains found in the
when the matter concerns paleontological material). It means Holocene channel alluvium is not a surprise. Naturally,
that if body size is different it is likely that the entire complex terraces that were situated directly next to the flood plain,
of taxonomically significant features is different. i.e. lower, or younger - Late Pleistocene, were the first
Therefore, modification of the complex of features linked to be washed out when the Holocene flood plain level
to ontogenesis, which occurs as an effect of environmental was forming. We cannot yet be sure of which terraces
conditions, should have an impact on the most taxonomically served as the source of the remains from the aforemen
tioned fossilisation groups. However, it is possibly at important and biostratigraphically informative characterist
the very least to exclude the alluvium of the Fourth ics of rodent morphology. And, taking into account a scale
of Pleistocene climatic oscillations, environmental changes terrace above the flood plain as the source of the secon
dary taphocoenoses described here. Its Middle Pleisto could produce noticeable inaccuracy in evaluation of the evo
cene (Holsteinian) age has been amply demonstrated. lutionary level (age) of a fauna.
The Fourth terrace above the flood plain has yielded Micromammalian material from the modern channel all
small mammals remains of the Singil complex (Markova, uvium of the Dnieper River allows to reveal the relationship
between the spectrum of morphological variation of palae- 1982) - (attributed to the Holsteinian interglacial) and
this fauna, without any doubt, is older then the oldest opopulations and past environmental conditions. The main
remains under consideration here. object of the study is the water vole. Firstly, remains of
It is important to note that remains coeval with the alluvial this species within the assemblages of the Dnieper chan
suite that contains them make up a relatively insignificant nel alluvium are numerous enough to perform quantitat
share of the composition of the taphocoenosis. hi the modern ive analyses. Secondly, the living conditions of the Late
channel alluvium of the Dnieper, it can be seen that Holocene Pleistocene water vole from the Lower Dnieper signifi
remains (If), i.e. of the age closest to the time of flood plain cantly differed from the ones of water voles from Middle
Dnieper area. Thirdly, the modern water vole is a well- formation, make up no more than 15 % of the whole fauna.
Remains assigned to the Skurlatovo fauna of the first half studied species in terms of its population ecology, there
of the Late Pleistocene are dominant (Illf, more then 60 %). fore it is possible to apply modern population ecology
When studying taphocoenoses of mixed age, it is necessary advances to the fossil material, while paying special
to take into consideration the evolutionary level of the younge attention to the ontogenetic component in morphological
st part of the fauna, which should be coeval with formation variability.
Material. The material from the Dnieper River point of the given alluvial suite, while older remains are considered
bar beaches, on which the morphotypical analysis of to be reworked.
the Late Pleistocene Arvicola terrestris populations was Conclusions. Small mammal remains collected from point
based - numbers 800M,s (sample from Middle Dnieper), bar beaches have been washed out from the modern channel 239
and 53OM,s (sample from Lower Dnieper beaches, which
have now been submerged by the Kahovka r™> I»
order to establish the ontogenetic and geographical varia specimens during Intro-posterior suchTs tional D^oup nlconid, re-sedimentation triangle - fig weakly-differentiated present often 3b). on aspect, its It showing that was inner possess of and thought alluvium. the side an development other triangles, asymmetncal (i.e., at first However, juvenile morphotypes that a of squashed morphinthere y-shaped features an add, ot are a tion present in recent water voles, 100 skulls from dif
ferent areas of Eastern Europe were studied (matenal is
hous d in the Zoological museum of «he State University
of Taras Shevchenko, and also in Shmalgauzen s Institute es with additional triangles on the unpaired loop of the
anteroconid (D and E on fig. 3b) were the result of pro-
^ of unfavourable conditions eressive morphological differentiation (Markova 1982)
However studies of recent material have shown that such
a structure is peculiar almost exclusively to juvenile and S
modern individuals have a
the same - from morphotype Bl to A3 (fig. 3b). Howe
Z Z southern sample (from the Lower Dnieper) was
«nguishedbyahigher percent ofC-groupmorpho morphotype (very rare in modern populations) also
tvnes with a mushroom-like unpaired loop (fig. 4). This Occurs (fig 3b). Thus, every ontogenet.c stage of a
SsTnat geographica. variability of «his feature may be ™tër vole as well as phylogenetic stage of
clearly observed and must therefore be explained. Tlinlge, may be distinguished by a specmim
JfcsuHsThe study of the motphotypical composition of morphotypical diversity. However, on matenal
of fte different ontogenetic stages in recent water vo es tZZ from the modern channel Dnieper alluvium
we cannot establish whether unfavourable land cape- h s shown «ha. type «C» are senile morphotypes (mor
Pleistocene W Uo photypes «hat are usual for old individuals, aged 1 year dmatic changes through the Late
^ the return of archaic morphotyp.cal *™™*r™V
f has Withtthe limits of every such group the climate
rial and are consequently not represented in fig. 4. It is repeatedly changed in a considerable way.
possible «hat «hese «ee«h were fragile and were destroyed
morphotypes: A12c2t3 B12C213 C12c2t3 D12c2t3E A12c2t3 B12c2t3 C12c2t3 Dl2c2t3 E
(Illf, Hf, If- groupes de fossilisation)
Fig 5: archa p thian, 7-8 -illustration o 240
the Mimomys-fo\d and three more have signs of the
development of this structure in previous ontogenetic
stages (namely an underdeveloped extra entrant angle
in the anteroconid). This value is even greater than in
Middle Pleistocene subspecies E. talpinus tschernojari-
cus Alexandrova, 1976. Late Pleistocene remains from
the Dnieper Holocene alluvium (Illf and Ilf) do not have
the Mimomys-fold at all. A high frequency of the Mimo-
mys- fold has also been observed in remains of molerats Senex(n=15) Ad2(n = 31) found in Holocene buried soils (Rekovets, 1985a). (7**i- momys Al 2c 2t3 Adl(n = 27) Cl 2c » 3 ——m—^^^^^tiH^m — 01 — 21) morphotypes
Discussion.
Two facts can be proposed as the start point for further Fig. 6: Dynamics of the morphotypical composition of recent water
vole (by the age groups). discussion: Fig 6 Dynamique de la composition morphotypique d'Arvicola a) The growth-rate study of recent Arvicola has shown actuels selon les groupes d'âge
that age structures of water vole populations in the tundra
and temperate zones are very different (in the first case Furthermore, analysing the possible effect of cold
population age structure is characterised by relatively stages on the morphotypical variability of water voles
high percentage of younger animals and absence of senile using material from localities of other taphonomic origin
stages during a year) (Panteleev, 2001). b) The features is also not quite effective enough because biotopes appro
of more ancient forms are displayed on the early ontopriate for Arvicola are limited in the periglacial zone (and
genetic stages in recent Arvicola (for example, the SDQ consequently so are its fossils). A sample of water voles
is greater or equal than 100 in juvenile individuals of from Novgorod-Siversky (northern Ukraine), a locality
modern A. terrestris as in extinct Middle Pleistocene that has obvious periglacial features of faunal composit
forms (Kratochvil, 1980) and morphotypical composition, has also been studied. Morphotypical analysis of
ion in sub-adult water voles is characterised by a high this sample has demonstrated relatively high frequency of
frequency of archaic structures). juvenile and ancient morphotypes. More than half of the
These phenomena (b) can be explained by the foArvicola terrestris from Novgorod-Siversky has asymm
llowing three reasons: modifications of the water vole etrical morphotypes M, (B-l, B-3) (fig. 7). In water
phenotype under climatic conditions, genetic fixation of voles from localities of comparable age (second half of
the juvenile morphology, and change of populations age the Late Pleistocene) but situated further to the south
structure. Let's note that the third reason alone was suffi- Mezhyrych (fig. 7.7, 7.8), or Ilf of the Dnieper river
cient to lead to the archaization of population morphologalluvium - these archaic features of Ml structure appear
ical structure. much more seldomly.
The same features (fig. 5.6) as well as small size are
characteristic in the recent mountain form A. sherman
Shaw. Compared to other water voles, it has an ecologi
cal peculiarity in that its bond with water bodies has been
weakened and following the hydrobiont principle (Pan-
teleev, 1968), the size of the animals has been reduced.
In contrast to A. sherman, water voles from the Novgor
od-Siversky association apparently existed exclusively
in biotopes adjacent to water, on account of the develop
ment of permafrost on the watersheds. Body size in the
Novgorod-Siversky water voles are consequently larger
(Rekovets, 1985b), although they are smaller than the
Late Pleistocene and modern forms from the Dnieper
River.
An important confirmation of the assumption concern
ing the relationship between environmental change and
morphotypical composition is given by a form that is
ecologically distinct to water voles - Ellobius talpinus
Pall. While episodes of cold climate were unfavourable
for water voles, the Holocene warming and wetting of
climate was fatal for a range of Pleistocene tundra-steppe
animals. For example, E. talpinus now resides only in
Fig. 7: A. terrestris from Late Palaeolithic sites of Ukraine: 1-6 - Crimea, though its remains are common in the assembla Novgorod-Siversky (5 - with a trace of Mimomys-fold), 7-8 - ges under consideration here. In the most recent of these Mezhyrych.
Fig 7 Structure My chez les A terrestris des stations du Paléolithique remains, If of Holocene age, the Mimomys-îo\à. is fr recent d'Ukraine 1-6 - Novgorod-Severs ky (5 - avec un pli de Mimo- equently observed. Three specimens out of six have mys), 7-8 - Mezhyrych