Preliminary notes on the mammals from the prehistoric deposits of Dieu Rock- shelter (North Vietnam) with descriptions of Aeromys sp. (Rodentia: Petauristinae) and Nesolagus cf. timminsi (Lagomorpha: Leporidae) and their importance for historical biogeography of SE Asia

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Saxa loquuntur 203
Keywords
Aeromys, Nesolagus, , Dieu Rockshelter
and Cave, Late Pleistocene, Early Holocene
Резюме
 Представени са първи резултати от
обработкатанакостнияматериалотбозайни-
ци,събранповременавиетнамско-българ-
скиархеологичниразкопки,проведенипрез
1988, 1989 и 1991 г. в скалния навес Диео
(100м над морскоторавнище, 20o24’30’’N
and 105o16’20’’E)вдолинатанарекаМъонг
Ай (ляв приток на река Ма) в областта Ба
Тхъкна провинцияТанХоа(СеверенВиет-
нам).
 Разкопките разкриха два ясно раз-
личми типа седименти. Първият тип (слой
9) е компактен, глинест, жълтеникав и съ-
държазъбиоторангутан(Pongo pygmaeus),
тапир (Tapirus sp.) и носорог ( Rhinoceros
sp.). Тези отложения не съдържат археоло-
гическиматериал.Най-вероятносеотнасят
къмранниякъсенплейстоцен. Вторияттип
наносипредставлявагорнатачастнасеквен-
цията (слоеве 1-8) и се състои от относи-
телно неуплътнени седименти, съдържащи
каменни артефакти и животински останки.
Според получените абсолютни радиовъгле-
роднидатислоеве 8-5 трябва да се отнесат
къмкъсниягоренплейстоцен,слоеве4в-4а
представляватпреходакъмхолоцена,асло-
еве3а-1принадлежаткъмраннияхолоцен.
 Животински останки от бозайници,
птици,влечуги,раци(Ranguna kimboiensis),
кактоипресноводниисухоземнимолюскисе
срещатвизобилиевархеологическитеслое-
ве(1–8).Начупванетонакоститеипризна-
цитезаизгарянепоказват,четовасаостанки
отчовешкахранаи указватнадейности за
обработканахраната.Нямасвидетелстваза
предпочитанвид,катообектналов,новсе
пакследвадасеотбележи,чесредкоститена
бозайниципреобладаваттезинамаймунии
особенонаедърмакак,мунджак(Muntiacus
cf. muntjak), дива свиня (Sus scrofa ) и се-
роу (Nemorhaedus sumatrensis ). Изобилие-
то от пресноводни молюски (главно Brotia
(Antimelania) costula)предполагасъбиране-
тоимпрезсухиясезон,докатосухоземните
охлюви,Cyclophorusspp., можебисабили
събиранипрездъждовнияпериод.Останки-
те от животни доказват, че мястото е било
обитаванопостоянноотмалкигрупипраис-
торическихораповременасухитеивлаж-
нитесезони.Населениетосеепрехранвало
чрезнеспециализиранловисъбирателство,
експлоатирайки разнообразни местообита-
ниявоколноститенаскалниянавес.Лову-
ванетовероятноебилонаслучаенпринцип,
присрещасплячка,наотносително близко
разстояниеотлагера.
 Дадено е описание на два вида бо-
зайници, които представляват специален
биогеографскиинтерес-Aeromys sp.(пласт
5) и Nesolagus cf. timminsi (пласт 2а). Тези
таксонипоказватвръзкасъс съвременнната
зондскафауна.Дватавидалетящикатерици
Preliminary notes on the mammals from the prehistoric deposits of Dieu Rock-
shelter (North Vietnam) with descriptions of Aeromys sp. (Rodentia: Petauristi-
nae) and Nesolagus cf. timminsi (Lagomorpha: Leporidae) and their importance
for historical biogeography of SE Asia
Vasil Popov*
Fig. 1.MapofSEAsia(landinblack),show-
ing the extension of Sundaland during the Last
GlacialMaximum(grey),thepositionofthe
locality and the boundaries of the Inochinese
and Sundaic biogeographic provinces(dashed
lines).

Saxa loquuntur 204
отродAeromysднессе срещат в зондската
биогеографскапровинциянаюготпровлака
Кра.Доскороотрод Nesolagus беше извес-
тенсамоединвид(N. netscheri),срещащ се
самовнякоирайонинао.Суматра.Съвсем
наскоро(през2000г.)бешеописанноввид
оттози род(N. temminsi )отСеверенВиет-
нам.Досегалипсвахапалеонтологичнидан-
ни,коитодададатинформациязаеволюци-
оннатаисториянавидоветевтезидварода.
Коментираноеприсъствиетонатезитаксо-
ни, екологично и еволюционно свързани с
дъждовнитеекваториалнигори,презкъсния
плейстоценвСеверенВиетнам,вконтекста
на палеогеографските промени (изменения
в морското ниво и палеоклиматични флук-
туации). През късноя плейстоцен климатът
на обширни райони от северните части на
индокитайскатабиогеографскапровинцияе
билзначителнопо-хладенисух,авлажните
горисабилисмалкаплощ.Разпространени-
етонаюжниформиобачеебилоулесненоот
наличието на периоди с широка сухоземна
връзка, през плиоцена и плейстоцена, през
днешнатаакватория на Зондския шелф. За-
пазванетона тези южниформипрезнебла-
гоприятнитеклиматичнипериодинакъсния
плейстоценнай-вероятноседължинаобсто-
ятелството, че източните склонове на Ана-
мититесабилирефугиумнависокостъбле-
нитропични гори, поради особеноститена
дъждовния режим – валежите вероятно са
били сравнително високи дори и през су-
хитепериодинакъснияплейстоцен.Еколо-
гичниятобликнабозайнатафаунаотархео-
логичните пластове на скалния навес Диео
потвърждаватова.
Introduction
Initially explored in 1986 by a Vietnamese
group (Cuong 1986), Dieu Rockshelter was
excavated in 1988, 1989, and 1991 by a joint
Vietnamese-Bulgarian team led by Dr. Hoang
XuanChinh(Archaeological Institute–Hanoi)
and Dr. Nikolay Sirakov (Archaeological
Institute and Museum, Bulgarian Academy
Sciences–Soa). Besides the prehistoric lithic
artifacts, site yielded a collection of a large
number of faunal remains. Although the Late
Quaternary mammalian fossil record is rela-
tively well known in Vietnam (Cuong 1985,
Olsen et Ciochon 1990, Ciochon et alli 1996;
Schwartzetalli1994,1995)everynewlocal-
itywouldcertainlyaddtoourunderstandingof
historical biogeography of this region, home
to a diverse and distinct mammalian fauna
(Surridgeetalli1999).
The Indochinese and Sundaic Provinces
are the major biogeographical regions of SE
Asia (Fig. 1). They are distinct climatically,
oristically and faunistically. The present-day
boundary between them is located at the Kra
IsthmusinpeninsularThailand.Themajority
of the mammals collected from the archeologi-
cal layers of Dieu Rockshelter are of Indochi-
neseafnity orarewidespreadinSEAsia and
stillliveinthearea.Howeverthepresenceof
twoforms,Aeromyssp.andNesolaguscf. tim-
minsi, meritsspecialattentionsincetheyshow
aSundaicafnity.Thepaperpresentsabriefde-
scription of the area and locality, a preliminary
Fig. 2.LocationofDieuRockshelter.Shaded
areamarksrivervalleysandplainsbelow200
mabovesealevel.Trianglesrepresentlocal
peakswiththeiraltitudeinmeters.
Fig. 3. Annual changes of temperature range
(shaded)andprecipitationintheareaofDieu
Rockshelter

Saxa loquuntur
205
list of mammals collected from archaeological
layers and a detailed description of Aeromyssp.
and Nesolagus cf. timminsi, recorded for the
rsttimeasfossilsinIndochinesePeninsula.
Area and present-day environment
 Dieurockshelterislocatedatca.100m
abovesealevel(20o24’30’’Nand105o16’20’’E)
in the valley of the Muong Ai River (a left tribu-
taryofMaRiver)inBaThuocdistrictofThanh
HoaProvince(Fig.2).
The area is the southeast extension of
the NW Vietnam karst range that is regarded
Fig. 4. StratigraphicproleofthedepositsofDieuRockshelter

Saxa loquuntur 206
typical of the karst peak cluster-depression
landscape. The karstied limestone belongs
totheDongGiaoandMuongTraiformations.
The slopes are often steep or sometimes are
thescarps.Elevationrangesfrom50mtomore
than 1000m and the highest summit in the area
is1046mabovesealevel(Fig.2).
The climate of this region is clearly
monsoonalwithtwodistinctseasons–wetand
dry.ThedryseasonisfromNovembertoApril,
the driest months being December and Janu-
ary(Fig.3).Onaverageitrainsmorethan200
days a year and the average annual rainfall is
ca1800mm.Theaverageannualtemperatureis
22.8 o
 C, with a Mean Temperature of Warm-
estQuarter27.5 o C and Mean Temperature of
Coldest Quarter 17 o
 C (Hijmans et al. 2005,
http://www.worldclim.org/current.htm).
The indigenous vegetation of this area is
a semi-evergreen rain forest, commonly called
monsoonforest,which hasbeendegradedand
fragmentedasa resultofhumanactivity. Rice
eldscoverthealuvialplains,whilelowerhills
andplateaus consistofarable eldsotherthan
rice and bamboo coppices. Patches of ever-
green forest still occur around the outcrops of
limestone and on the hill slopes, for example on
thehillabovethelocality.
 Accordingtolocalhuntersthefollowing
mammals inhabit the area: pygmy slow loris,
gibbon, Asiatic black bear, otter, hog badger,
cloudedleopard,leopardcat,wildpig,sambar,
barkingdeer,serow,chinesepangolin,burnese
striped tree squirrel, black giant squirrel, giant
yingsquirrel,bamboorat,rats,mice,etc.
Locality and excavations
The site represents a complex of a rock-
shelterandasmallcave.Thesitewasexcavated
inupto a totaldepthof5m (Fig.4).Thearea
was excavated in units 10cm in depth, subdi-
vided stratigraphically when possible. The
depthofthestoneartifacts,andlargeboneswas
measured before they were taken out and all
dataweredocumentedonthesheets.
 All the excavated sediment was dry-
sievedbytheworkmen,usingameshofabout3
mm.Alargenumberofsedimentsampleswere
wetscreenedin anarticialpondnear thesite
using1mmmeshbags.
The excavations in the rockshelter re-
vealedtwodistincttypesofdeposits(Fig.4).
 Thersttypeofdepositcomprisesthe
lowerpartofthesequence(Fig.4,layer9).Itis
compact,loamy,yellowishincolorandcontains
teeth of Pongo, Tapirus, and Rhinoceros.The
sediments inside of the cave correspond prob-
ably to this stratum, and beside the above men-
tioned genera, extinct in this part of the penin-
sula, they also contain another locally extinct
mammal - Ailuropoda melanoleuca.Thesesed-
imentsdonotcontainarcheologicalmaterial.A
similar fauna containing Pongo pygmaeus from
WuyunCave(SouthernChina)wasreferredto
Middle or early Late Pleistocene on the basis of
U-seriesdatings(Wangetalli2007).Dateses-
timated for the different remains of P. pygmae-
us in Vietnam range from 300–250 ka (Tham
KhuyenCave) to 23 ka (Nguom Rockshelter)
(Cuong 1992, Schwartz et alli. 1994, 1995).
According to Schwartz et alli. (1995) the age
Fig. 5. Aeromyssp.Occlusalsurfaceofright
uppercheekteeth(P3–M3),DieuRockshel-
ter,layer5.Scalebarrepresents1mm.

Saxa loquuntur 207
of layer 9 from Dieu rockshelter is compara-
blewiththose ofthenearbyLangTrangCave
which is now considered to be younger than
Middle Pleistocene. Most probably layer 9 of
Dieu Rockshelter is of early Late Pleistocene
age.
The second type of deposits (total thick-
nessof4-5m)comprisedtheupperpartofthe
sequence(layers1-8)andconsistedofrelative-
ly loose sediments containing stone artifacts
andfaunalremains.AccordingtoCuong(1986)
the upper portion of the cultural sequence up to
0.8m from the surface contains stone objects
typicaloftheHoabinianculture,whilethesedi-
mentfrom0.8 to 1.4mcontainsstoneobjects
assigned to the Son Vi culture. Radiometric
datingwascarriedoutattheGliwiceRadiocar-
bon Laboratory (Poland, Silesian University of
Technology Institute of Physics, Departament
of Radioisotopes). According to the obtained
radiocarbon dates (Fig. 4) layers 8 - 5 should
be attributed to the late Upper Pleistocene, lay-
ers4b–4arepresentsthetransitiontowardthe
Holocene,whilelayers3a-1areattributableto
theEarlyHolocene.
Faunal remains of large and medium
sizemammals,birds,reptiles,crabs(Ranguna
kimboiensis Dang, 1975) and both freshwater
and terrestrial mollusks occurs in abundance
through the archaeological sequence (layers 8
–1).Thebonefragmentationandsignsofburn-
ing suggest that they represent human food de-
bris and indicate food-processing activities at
the site. No single species was preferentially
targeted, however monkeys, and especially a
largemacaque,barkingdeer,wildpig,and se-
row appear to be predominant mammals spe-
ciesfoundatthesite.Theabundanceoffresh-
water molluscs [mainly Brotia (Antimelania)
costula (Ranesque, 1833)], suggests collec-
tioninthedryseason,whilelandsnails(Cyclo-
phorusspp.)mighthavebeencollectedduring
thewetseason.Ingeneralfaunalremainstes-
tifythatthesitewascontinuouslyoccupiedby
smallprehistoricgroupsduringthewetanddry
seasons. Faunal remains suggest that foragers
employed a generalized subsistence strategy,
exploiting a wide range of habitats through a
mixed economy including hunting and collect-
ing.Huntingwasprobablyonanencounterba-
sisatarelativelyshortdistancefromthecamp.
Mammals from prehistoric layers of
Dieu Rockshelter
The mammalian remains from the ar-
chaeological layers of the rock-shelter, form-
ing the human food remains include bones
andteethofthefollowingforms:Easternmole,
Talpa cf. micrura Hodgson,1841;red-toothed
shrew, Soriculus sp; white-toothed shrews,
Crosidura spp.; commontreeshrew, Tupaia glis
(Diard,1820); macaques, Macaca sp. (large),
Macaca sp. (small);langur, cf. Trachypithecus
sp.; gibbon, Hylobates (s. l.) sp.; Annamite rab-
bit, Nesolaguscf. timminsi; black giant squirrel,
Ratufa bicolor (Sparrman, 1778); squirrels,
Dremomys sp. and Callosciurus sp.; red giant
ying squirrel, Petaurista petaurista (Pallas,
1766); largeblackyingsquirrel, Aeromys sp.;
bamboo rat, Rhizomys pruinosus Blyth, 1851;
rats, Leopoldamys sp., Niviventer sp., Rattus sp.;
porcupine, Hystrix cf.hodgsoni (Gray,1847);
bush-tailed porcupine, Atherurus cf.macrourus
(Linnaeus,1758);Asiatic black bear, Selenarc-
tus thibetanus G.Cuvier,1832; marten, Martes
sp.; hog badger, Arctonyx collaris F. Cuvier,
1825; otter, Amblonyx cinereus (Illiger,1815),
ferret-badger, Melogale personata I.Geoffroy,
1831; Owston’s palm civet, cf. Chrotogale
owstoni Thomas, 1912; masked palm civet,
Paguma larvata (H. Smith, 1827); common
palm civet, Paradoxurus hermaphroditus (Pal-
las, 1777); spoted linsang, Prionodon pardi-
color Hodson,1814; large Indian civet, Vivera
zibetha Linnaeus,1758; Javan mongoose, Her-
pestes javanicus (E. Geoffroy, 1818); leopard
cat, Prionailurus bengalensis (Kerr, 1792);
wildpig, Sus scrofa Linnaeus,1758; barking
deer, Muntiacus cf. muntjak (Zimmermann,
1780); hog deer, cf. Axis porcinus (Zimmer-
mann,1780); sambar, Cervus (Rusa) unicolor
Kerr,1792; Chinese water deer, Hydropotes
inermis (Swinhoe,1870), serow,Nemorhaedus
sumatrensis (Bechstein, 1799).Althoughthese
taxonomic attributions are provisional, pend-
ing additional study it is clear that the fauna has
a recent character.There are no considerable
stratigraphic changes in the species composi-
tion or abundance of particular forms through
thearchaeological layers (1 – 8).As a whole,
the mammalian assemblage suggests that dense
woodland or forest existed during Late Pleis-
toceneandEarlyHoloceneinthearea.Inpar-

Saxa loquuntur
208
ticular continuous occurrence of gibbon, lan-
gur, macaques,blackgiantsquirrel,giantying
squirrel,etc.throughoutthesequence indicates
closedcanopytallevergreenforest.
Systematic paleontology
Aeromys sp.
 (Fig.5)
 Material: 1 fragment of maxilla  with
P3-M2andalveoliofM3fromlayer5.
 Measurements (mm): Alveolar length
P3-M3=15.6;P3=1.80x2.30;P4=4.15x
4.35;M1=3.60x4.60;M2=3.60x5.00.
Description: On the available upper
cheek teeth the protoloph, metaloph and cin-
gula are crenulated; the hypocone is distinct;
with a lingual cingulum; no mesostyl; poster-
olophsareverylowrelative to metalophs; the
protoloph and the metaloph are approximatelly
parallel,connectingwiththeprotoconetoform
aU-shapedpattern.
 P4islargerrelativetoM1;itsocclusal
surface is subtriangular due to the antreolabial
expansion of the large parastyl; a well devel-
oped spur extending postero-lingually connects
the parastyl with the base of the protoloph,
separatingthevalleyinintotwo fossettes(an-
tero-andparafossette)thehypoconeisindistict,
incorporated to the base of the protocone, nev-
ertheless it is separated posterolingually from
the massive  protocone by a shallow depres-
sion;metaconuleislarge.
 M1-2.Protoconuleabsents;metaconule
iswell pronounced(M1);the hypoconeisdis-
tinct,wellseparatedfromprotocone;theanter-
olophislow;thereisadistinctsmallaccessory
lophule (extra lophule) between the proloph
andthemetaloph.
 Discussion.According to the lengthof
thecheekteethrow,thespecimenunder study
is intermediate between Petaurista petaurista
and P. elegans,comparableinsize with R. bi-
color . However the available maxilla differs
from the last mentioned species in the presence
ofP3,in havingacrenulatedocclusalsurface,
andinlackingamesostyle.
From the genera Petaurista and Aeretes
[A. melanopterus(Milne-Edwards,1867)]also
showinga highlycrenulateocclusalsurfaceof
the cheek teeth the available specimen differ in
lacking a posterolingual diagonal exus. This
exus is rather sharp in the above mentioned
twogeneraandrunsanterobuccalyfromapoint
immediately posterobuccal to the hypocone
(McKenna1962). Instead,inour teeththereis
ashallowhypoexus,separatingtheprotocone
andhypocone.This valleyisespeciallypoor-
Fig. 6. Nesolaguscf. timminsi1fragmentofleftmandiblewithp3-p4fromDieuRockshelter,
layer2a.A.Labialview,B.Lingualview,C.Occlusalviewofp3-p4.

Saxa loquuntur
209
lypronounced onP4,whileinPetaurista and
Aeretestherespectiveexusiswelldeveloped.
More over Aeretesshowsashorteruppercheek
teethrow(12.8-14.4mm).
 Thecrenulatecrownpatternand indis-
tinct hypocone clearly show that  the  molars
available belong to the Petinomys -group as
denedbyMcKenna(1962).Byitslargesize,
the absence of mesostyle and crenulation of the
protoloph, metaloph and cingula the avilable
upper dentition ts the diagnosis of Aeromys
and differs from the other genera in this group
such as Petinomys and Hylopetes. Recently,
Saha(1981)describedanewgenusandspecies
ofyingsquirrelfromnorthernAssam(India),
Biswamoyopterus biswasi,whichisclosetothe
members of Aeromys,inhavingsimpliedmo-
lariformteeth,butdiffersinhavingalargeP4,
largerthan M1.According tooriginaldescrip-
tiontheenamelofcheekteethinnotwrinkled
asinotherlargeyingsquirrels,especiallyin
Petaurista and in Belomys, Trogopterus, but
CorbetandHill(1992)foundthatcheekteeth
actually did not differ greatly from those of Pe-
tauristawithsimilarwear.
 Two species of the genus Aeromys oc-
cur today in SE Asia - A.tephromelas (Gunther,
1873),distributedinMalayPeninsula,Sumatra
and Borneo, and A. thomasi (Hose, 1900), re-
strictedtoBorneo(CorbetandHill1992).The
identicationoftheavailabledentitionwithone
ofrecentspeciesisdifcultsincethedifferenc-
esintheirtoothmorphologyarepoorlyknown.
Thus, it is here referred only as Aeromyssp.
 According to Lekagul and McNeely
(1977)itispossiblethatA. tephromelas occurs
alsonorthoftheIsthmusofKra-skinshavebeen
seen in shops in Chiengmai and Fang, Chieng-
maiProvince(north-westThailand),whichmay
representanorthernpopulationofthisspecies.
ItwasalsolistedforNamHaNBCA(Laos)by
Tizard et alli (1997). However, these reports
should be taken with caution, having in mind
that, at least locally, melanistic individuals of
the genus Petaurista occur,whichcanlookuni-
formly very dark  (e.g. Duckworth 1997) and
similar to A. tephromelas.So,avoucherspeci-
menwouldbenecessarytoconrmthespecies’
presencenorthofKraIsthmus.Inthisrespect
the fossil nd of Aeromys in North Vietnam
is quite interesting, indicating that this ying
squirrelmaystilloccurnorthofKraIsthmusin
analogywiththesituationwithgenusNesola-
gus,describedbelow.
Nesolagus cf. timminsi Averianov,
Abramov&Tikhonov,2000
 (Fig.6)
 Material:1fragmentofmandiblewith
p3-p4fromlayer2a.
Description:
 p3. There is a long posterior external
reentrant fold that extends nearly across the oc-
clusal surface of the tooth (initially the trigonid
andtalonidwerejointedlinguallybyaverynar-
Fig. 7.Longitudinal(E–W)variabilityofrelief(shaded)andannualprecipitation(line)across
easternpartofIndochinaat20o24’30’’N.

Saxa loquuntur 210
rowdentineisthmus,whichwasbrokenduring
thesubsequent preparation).Theenamelwalls
of this fold are smooth. The antero-external
reentrantiswide andnotlledwitha cement.
The antero-inetrnal reentrant fold is poor, lack-
ing cement. There is no anterior reentrant an-
gle.
 p4.Theexternalreentrantfold,separat-
ing the trigonid from the talonid is deep, ex-
tending to the internal margin of the occlusal
surface.Itsenamelwallsaresmooth.
 Discussion.Inspite ofthelownumber
of remains, the possibility of their belonging
to Lepus peguensis Blyth, 1855, another spe-
cieslivinginthearea, is out of question.The
p3of L. peguensispresents awelldeveloped
anterior reentrant fold, the anterior margin of
the posterior external reentrant fold is undulat-
ed,whiletheposterioroneishighlycrenulated
(Suchentrunk,2004).Thefossilformlacksan-
terior reentrant fold and the margins of the pos-
teriorexternalfoldaresmooth.
Until recently genus Nesolagus was
knownonlyfromtheisle ofSumatra.TheSu-
matran stripped rabbit, Nesolagus netscheri
(Schlegel,1880)isamongtherarestrepresenta-
tivesof the family Leporidae.   Recentlythe
strippedrabbitwasreportedfromLaosandVi-
etnam(Surridge et al., 1999) and subsequent-
lydescribedasa separate species –Annamite
stripped rabbit, Nesolagus timminsi (Averianov
etalli2000).Moleculargeneticanalysisreveals
aconsiderabledifferencebetweentheseforms,
comparablewiththedifferencesamongthegen-
erawithinLeporidae(Surridgeetal.,1999).
 Ingeneral,theocclusalpatternofp3is
similar to those of both recent forms of the ge-
nus - N. netscheri from Sumatra, as described
byHibbard(1963),andN. temminsifromNorth
Vietnam(Averianovetalli2000).Accordingto
the shape of the trigonid the fossil specimen is
closertotherstspeciesinhavingawellpro-
nounced antero-external fold. The differences
concern the presence of a small amount of ce-
ment in this fold and the lack of an internal con-
nectionbetweenthetrigonidandtalonidinthe
Sumatranstrippedrabbit. In these respects the
fossil specimen from Dieu rockshelter is simi-
lartotheAnnamitestrippedrabbit.According
toAverianov etalli (2000) in thetype speci-
men of N. temminsi “the trigonid and talonid
ofp3havebecomejoinedbyalingualdentine
bridgeabout2mmbelowtheocclusalsurface”,
while in N. netscheri this connection “…is
completely absent …, or it appears at a very late
ontogeneticstage”.On theotherhandthe fos-
sil specimen differs from N. temminsi in hav-
ing better developed both antero-external and
antero-internalreentrant folds.Since thevari-
abilityoftheshapeoftheocclusalsurfaceofp3
intherecentspeciesisnotknown,forthetime
beingitisdifculttoevaluatethesedifferences.
The material is tentatively referred to the An-
namite stripped rabbit on the basis of the spatial
proximity to the type locality. The fossil nd
from Dieu Rockshelter documents the presence
of stripped rabbit on Indochinese peninsula at
leastsincetheEarlyHolocene.
General discussion
The occurrence of Aeromys and Nesola-
gus,formsofSundaicafnity,inthispartofthe
Indochinese Penninsula during Late Pleistocene
andEarlyHoloceneisquitesurprising.Atrst
glance it seems unlikely that these forms, being
associatedwithtropicalrainforest,wereableto
exist here taking into account that during glacial
periods(around0.28and0.24myrandaround
0.18and0.125myr)theclimatewascoolerand
drier than present causing a decaying of the
forests(vanKaars1991;ZhengandLei1999).
AccordingtoTan(1985)duringtheLatePleis-
tocene,climateinNorthVietnamwasrelatively
cold and arid. During the transition from the
LatePleistocenetoEarlyHolocenetherewasa
humidandtemperateclimate.Theclimatethan
turnedwarmerintheHolocene,reachingmod-
ern conditions and the local vegetation is domi-
natedbyseasonaltropicalenvironment.So,the
presence of Aeromys and Nesolagus deserve
special attention.  Their presence in northern
part of Indochina may be explained by large-
scale climatic and eustatic changes associated
with periodic glaciations during Pleistocene
andtheirlocalmodications.
Major oscillations in the area of land
relative to sea on the Sunda continental shelf
have changed dramatically during the Neo-
gene in response to the collision between the
Indian-Australian and Eurasian plates and in
response to changes in global sea level. The
existenceofuvialsedimentsatdepthsinex-
cessof 200mtestiesto periodswhenrelative

Saxa loquuntur 211
sea-level was considerably lower than at any
timeintheQuaternary,whileperiodsofhigher
relative sea-level in the late Pliocene may have
oodedamuchlargerproportionofSundaland
thanis the case atpresent (Bird et alli2005).
Pleistocene sea level recessions during glacials
linked the present-day offshore islands to the
mainland forming a big continental landmass
calledSundaland(Hutchison1989).Asealow-
eringof50mbelowpresent-day sea level was
sufcient to transform the Malay Peninsula,
Sumatra, Java and Borneo, the Sunda region,
a peninsular extension of the Asiatic continent
(Fig. 1). The rst marked glacio-eustatic sea
levelloweringsarethoughttohaveoccurredat
2.4myr(VandenBerghetalli1996).Between
2.4and0.8myrtheeustaticsealevelisthought
to have shown moderate uctuations with a
mean of around 70m below present day level
andlowest sealevelsataround100m (Vrbaet
alli1989).DuringandsubsequenttotheSaale
Galciation the Sunda shelf was fully emerged
and the tropical fauna of South China and Indo-
china, including Pongo,wasforcedsouthward
along with their forest habitats, reaching Java
(Punung fauna), (Van den Bergh et alli 1996,
Tougard2001).Thelowestsealevelsduringthe
lastglacialmaximum(LGM)occurredbetween
0.295and 0.183 myr ago (Scho¨ nfeld&Ku-
drass, 1993) and were c. 120m below present
daylevel(e.g.Chappell,1998).As aresultof
global cooling and drying of climate during
LGM, together with a weakening of summer
monsoonal increased the extent of seasonally
dryconditions,whichpresumablyledtoacon-
traction of the humid forest and an expansion of
the biome of savanna/dry forest on the territory
of the central and northern part of Indochina,
including the area under consideration. Tropi-
calrainforestwasshiftedsouthward,covering
theMalayPeninsulasouthofKraIsthmus,Su-
matra, Borneo, Palavan, and the land exposure
in the recent aquatory north of Borneo (Hope
etalli2004).Inparticular,pollendatafromSu-
matrawhereAeromys and Nesolagus occur to-
day, indicate the possible presence of a refuge
for montane rain forest during the later stages
ofthelastglacial(Maloney1980,1981).
These large scale environmental chang-
eswereaccompaniedbyvariationsinlocalcli-
mate, humidity and precipitation due to latitude,
topography,andrainshadoweffects(Kershaw
etal.2001).Accordingly,theexistenceoffor-
est refugia during glacial periods has been pos-
tulated for the Annamite Mts (Brandon-Jones
1996). It can be supposed that, as today, the
eastern side of the Anamite Mts has more rain-
fallthanthewesternside(Fig.7),andforestsof
broadleaf evergreens may have persisted dur-
ing last glaciation along the eastern slopes of
theAnnamiteRange(SchallerandVrba,1996),
providingabridgebetweensouthernandnorth-
easternpartsoftheSundaland.Inthisrespectit
is important to note that today southern Yunan
hastropicallowlandevergreenrainforestsimi-
lar to that found in Malaysia, even though the
rainfall is decidedly seasonal and the climate is
cooler(Whitmore,1984).
 Itcanbehypothesizedthattheoccur-
rence forest refugia and the land exposure in
the recent aquatory of the southern Sunda shelf
during Pleistocene glaciations fascilated the
north-south faunal exchange and explains the
occurrence of Aeromys and Nesolagus in north-
ern part of Indochinese peninsula. During the
Holocene break-up of the Sundaland the north-
ern and southern portions of the range became
isolated. As a result from this fragmentation,
and the onset of a more seasonal climate dur-
ing the mid-Holocene Aeromys probably has
gradually extinct in the east-northern part of
Indoshina,whilethenorthern form ofNesola-
gusstillexistsinsomeareasofformerrefugia.
The large genetic distance indicates that both
Nesolagus species have been geographically
isolated in refugia for millions of years (Sur-
ridgeetalli1999). Most probablytherewasa
deephistoryofvicariantevolutionbetweenthe
various populations of these species on Sunda-
land.   Hewitt (1996) and others have argued
thatEarlyPlioceneenvironmentaleventswere
a major impetus to speciation, and that cycli-
cal Pleistocene changes have had more impact
onsubspecicpatterningandextinctions.Most
probably marine transgressions during the Mi-
ocene and Pliocene that have separated Indo-
chineseandSundaicprovinceswereafactorfor
faunal isolation (Hughes et alli, 2003). Latter
on, the Gulf of Thailand and the associated river
systemwhensea levels werelow(SiamRiver
system),(Voris2000,Birdetalli2005)served
as barriers preventing the mixing of these sepa-

Saxa loquuntur 211
ratepopulations.
The ecological appearance of the mam-
malian fauna from the archeological layers of
Dieu rockshelter (layers 1 – 8) corresponds
fairly well with this scenario. In general, due
to the absence of Pongo and Tapirus it can be
supposedthat theclimatewassomewhatcool-
er and drier than that during Middle and early
LatePleistocene. Nevertheless the appearance
of the mammalian assemblage from the archae-
ological layers is similar to the recent one in
thearea,indicatingarelativelywetclimateand
widedistributionofforestinthearea.Although
the middle part of the sediment sequence (lay-
ers7–5)coverstheperiodsknownascooler
anddrier(seeabove),thestructureofthefos-
silmammalianassemblagesdoesnotchange.It
canbesupposedthattheareawasastableforest
refugiumatleastduringtheLatePleistocene.
The above interpretation is conrmed by the
factthat the area under study is located with-
in the territory of a present-day biodiversity
hotspot,identied onthebasis ofdistributions
ofendemicbirds(Longetalli1996)andcolo-
binae monkeys (Brandon-Jones 1996). Biodi-
versity hotspsots are usually considered as an
imprintofpastaswellaspresentenvironmen-
tal conditions, indicating the location of refuges
for a formerly more continuous rain forest biota
(Brandon-Jones1996).
Acknowledgements
 Mysincerest  thanks to Dr N. Sirakov
without whose insight and energy Bulgarian
Quaternarypaleontologywouldbeamuchless
rewardingsubject.Theeldworksimplycould
not have been accomplished without the help
ofDrsS.Sirakova,S.Ivanova,Ts.Tsonev,and
I.GatsovfromtheArchaeologicalInstituteand
Museum, Soa. I am immensely grateful for
theirfriendship,goodhumourandunwavering
attention to detail in what were very difcult
conditions at times. My special thanks to the
staff of the Institute of Archaeology - Hanoi,
RepublicofVietnam,andespeciallytoProf.H.
X.ChinandDr.N.V.Binh,forintroducingus
to their country and providing every opportu-
nitytopursueourresearchandmadeeldwork
enjoyable. Dr Vu The Long  (Institute of Ar-
chaeology- Hanoi, Republic of Vietnam) in-
troduced me to the mammalian Late Quatenary
paleontologyofNorthVietnamandhelpedme
gain access to many collections of fossil and re-
centmammals.Ihopethisreportmakesacon-
tributiontohisresearchinthisregion.Thanks
also to the late Prof. Cao Van Sung (Institute
ofEcologyandBiologicalResources- Hanoi)
whoofferedstimulatingdiscussionsabouttax-
onomy and biogeography of small mammals in
SEAsia.TheoriginalofFig.4wasdrawnbyS.
Ivanova.
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