Mammals from the Age of Dinosaurs: Origins, Evolution, and Structure

649 Pages·2004·6.14 MB·English

by  Zofia Kielan-Jaworowska

Distribution: Mesozoic Mammals in Space and Time 59
TABLE 2.14. Early Cretaceous Mammals ofNorth America (see figures 2.10,2.14,2.15;locality numbers do not correspond
between table and maps).Localities:1,Paluxy Church (Twin Mountains Formation,Aptian);2,Pecan Valley Estates (Paluxy
Formation,Albian);3,Greenwood Canyon;4,Butler Farm;5,Willawalla;6,Umsted Farm;7,McLeod Honor Farm (all Antlers
Formation,Aptian–Albian);8,Bridger (two sites,undifferentiated here);9,Cashen Ranch;10,Cottonwood Creek;11,Crooked
Creek;12,Ninemile Hill (all Cloverly Formation,Aptian–Albian);13,Coalville (Kelvin Formation,Aptian–Albian);14,Muirkirk
(Arundel Clay,Aptian)
Mammalia incertae sedis(11,12,13) Stem Boreosphenida (“tribotherians”)
Eutriconodonta Family incertae sedis
Gobiconodontidae Comanchea hilli(2)
Gobiconodon ostromi(8,9) Slaughteria eruptens(4)
Triconodontidae Gen.et sp.indet.(1,7,9,10,11)
Gen.et sp.indet.(10,11) Kermackiidae
Arundelconodon hottoni(14) Kermackia texana(3)
Astroconodon denisoni(1,3,4,7) Trinititherium slaughteri(4)
Astroconodoncf.denisoni(5,6) Pappotheriidae
cf.Astroconodonsp.(8,9) Gen.et sp.indet.(7)
Corviconodon montanensis(9) Holoclemensia texana(3,4)
Multituberculata Pappotherium pattersoni(4)
Family incertae sedis ?Deltatheroida
Gen.et sp.indet.(1,7,9) Family incertae sedis
?Paracimexomys crossi(7) Atokatheridium boreni
cf.Paracimexomyssp.(3,4,11) cf.Atokatheridium boreni
Stem Trechnotheria (“symmetrodontans”) Eutheria
Spalacotheriidae Family incertae sedis
Gen.et sp.indet.(10) Montanalestes keeblerorum(10)
Spalacotheroides bridwelli(3)
cf.Spalacotheroidessp.(7,10,11)
Eutheria (Pappotherium) were present in the fauna, but Wyoming,is well known for its dinosaur fauna (Ostrom,
evidence for this is tenuous (Butler,1978a;Jacobs et al., 1970).Age constraints on the unit are imprecise;it is older
1989; Cifelli,1999b),and they are treated later (chapter than the overlying Thermopolis Shale,which is estimated
11) as “tribotherians.”Both Greenwood Canyon and But- on the basis of marine invertebrates to be early late Al-
ler Farm are reportedly no longer accessible (Winkler et bian (Jacobs et al.,1991;Jacobs and Winkler,1998).The
al.,1989),but ongoing investigations at other localities of Cloverly is generally assigned an Aptian–Albian age based
the Trinity Group ofTexas are being carried out by Louis on the similarity ofits vertebrate assemblage with that of
L.Jacobs,Dale A.Winkler,and associates,also at Southern the Trinity Group (see,e.g.,Brinkman et al.,1998).The
Methodist University (e.g.,Jacobs et al.,1989;Jacobs and Cloverly consists of fluvially deposited claystones, silt-
Winkler,1998;Winkler et al.,1990). stones, and occasional sandstones, with color banding
The Antlers Formation also crops out in a narrow band suggestive of paleosol development. Three units of the
along southern Oklahoma.Field parties led by Richard L. Cloverly Formation, V–VII, are recognized in Ostrom’s
Cifelli have recovered mammals from two sites,Umsted (1970) stratigraphic sequence, and each of these has
Farm and the McLeod Honor Farm, both in Atoka yielded mammals. Though fewer taxa are known than
County (figure 2.14).Mammals described thus far include from the Trinity Group,the Cloverly Formation is signif-
the multituberculate ?Paracimexomyscrossi;an unidenti- icant because it has yielded some rather complete speci-
fied (probably new) tribosphenic mammal (Cifelli,1997a); mens through surface prospecting and quarrying proce-
and a possible deltatheroidan, Atokatheridium boreni dures,as well as isolated teeth obtained through bulk rock
(see Kielan-Jaworowska and Cifelli,2001,and chapter 12). processing.
Several other mammals and a host of other microverte- Field parties led by Farish A.Jenkins,ofHarvard Uni-
brates are known from the sites (Cifelli, Gardner, et al., versity, made the initial discovery of mammals in the
1997),and work is continuing. Cloverly Formation in the 1970s,and work by Cifelli and
The Cloverly Formation, exposed along the margins associates is in progress.Lewis Pocket,southeast ofBridger
of the Bighorn Basin and other areas of Montana and (figure 2.10),yielded a remarkable series ofa triconodon-
60 DISTRIBUTION: MESOZOIC MAMMALS IN SPACE AND TIME
tid similar to Astroconodon, represented by nearly com- Lower Cretaceous unit known primarily for its dinosaurs.
plete skulls and postcranial elements (Jenkins and Most such fossils were collected in the nineteenth century,
Crompton,1979; Crompton and Sun,1985).The site is while the clay was being mined for the sedimentary iron
near the famous Yale Deinonychus Quarry (Ostrom, ore contained within it (Kranz,1996),and consist ofiso-
1970);fossils occur in limonitic nodules in unit V.About lated,largely indeterminate elements (see,e.g.,Gilmore,
2 km to the east,a second site in the Bridger area yielded 1921).The Arundel Clay is considered to be a facies within
jaws and postcrania of the large eutriconodontan Gobi- the Potomac Group and appears to represent swamp de-
conodon ostromi(see Jenkins and Schaff,1988).The site is posits in a system offluvial oxbows (Kranz,1998).The Po-
in the base ofunit VII. tomac Group is well known for its fossil flora; paly-
Fossil mammals have also been recovered from the nomorphs suggest an Aptian,probably middle Aptian,age
vicinity ofCashen Ranch (figure 2.10),southern Montana, for the Arundel Clay (Doyle, 1992). The only mammal
in the base ofunit VII ofthe Cloverly Formation.In addi- known from the Arundel Clay is the triconodontid Arun-
tion to Gobiconodon (see Jenkins and Schaff, 1988), the delconodon hottoni,based on a dentary found by Thomas
triconodontid Corviconodon (see Cifelli et al.,1998) and R. Lipka at a site near Muirkirk, Maryland (a second,
several undescribed taxa are present (RLC,unpubl.data). edentulous dentary from the same site is tentatively re-
A third area for mammals in the Cloverly Formation is ferred to the same species, see Rose et al., 2001). This
in the Cottonwood Creekdrainage,east of Edgar,Mon- species clearly belongs to an endemic North American
tana (figure 2.10).The productive zone,again in the base clade ofthe group,but is more primitive than other taxa
ofunit VII,has thus far yielded jaws ofseveral undescribed known from the Early Cretaceous of this continent
taxa,as well as the tribosphenic mammal Montanalestes (Cifelli,Lipka,et al.,1999).
keeblerorum(see Cifelli,1999b).Montanalestesappears to The Cedar Mountain Formation,Utah (figure 2.10),is
be a eutherian,which are known elsewhere in the Early of interest because it appears to include rocks spanning
Cretaceous only from Asia (Averianov and Skutschas, the Barremian through the uppermost Albian. Several
2000a; Ji et al., 2002). Eutheria are otherwise unknown superposed dinosaur faunas are known (Kirkland et al.,
from North America until the early Campanian (Fox, 1997) but,thus far,mammals are only known from the
1984b;Cifelli,1990e),which may not be surprising con- uppermost part ofthe Cedar Mountain Formation.Field
sidering the sparseness ofthe fossil record from the early studies by Jeffrey G.Eaton and Michael Nelson in 1983 led
Late Cretaceous. A second mammal from Cottonwood to recovery of the first mammals known from the unit
Creek is a spalacotheriid symmetrodontan similar to Spala- (Nelson and Crooks,1987;Eaton and Nelson,1991).Later
cotheroidesfrom the Antlers Formation ofTexas.The fos- investigations by Cifelli and colleagues, still continuing,
sil from Cottonwood Creek is a remarkably complete den- have resulted in a large,well-sampled collection,including
tary,including the canine and all postcanine teeth (Cifelli some 80 taxa ofvertebrates (Cifelli,Kirkland,et al.,1997).
et al.,2000). The fossil assemblage is from a restricted stratigraphic
A small microvertebrate assemblage,obtained through level in the Mussentuchit Member ofthe Cedar Mountain
screenwashing,is known from unit V ofthe Cloverly For- Formation and is termed the Mussentuchit local fauna
mation at Crooked Creek, northern Wyoming (figure (Cifelli,Nydam,Weil,et al.,1999).Mammals,known from
2.10).Two mammals are known from this site; one is a eight sites, were collected mainly through bulk matrix
triconodontid otherwise unknown from the Cloverly processing,though some well-preserved specimens were
Formation, so it documents a considerable diversity of found through quarrying.Most of the sites are in fluvial
these primitive mammals from the unit—at least four overbank deposits.A radiometric date of98.39 ±0.07 Ma
eutriconodontans are known from the Cloverly (Cifelli places the Mussentuchit local fauna at the Albian-
et al.,1998).A single mammalian tooth,a lower premolar, Cenomanian (Early–Late Cretaceous) boundary (Cifelli,
has been recovered from beds presumed to represent Kirkland,et al.,1997).
the Cloverly Formation at Ninemile Hill, Como Bluff, The fauna of some 28 mammal taxa (table 2.15) in-
Wyoming (Trujillo,1999). cludes at least three triconodontids (two genera,Astrocon-
A single mammal specimen, an unidentified petrosal, odonand Corviconodon,are shared with the Aptian–Albian
has been recovered from a site near Coalville,Utah (figure faunas of North America) and four “symmetrodontans”
2.10).The specimen is from the Kelvin Formation,reported (one genus, Spalacotheridium, is shared with younger
to be ofAptian–Albian age (Prothero,1983).The site has North American faunas),indicating a surprising diversity
also yielded dinosaur eggshell material (Jensen,1970). of these archaic groups.Both the triconodontids and the
The Arundel Clay,exposed in Maryland (figure 2.15) “symmetrodontans”belong to endemic North American
and adjacent parts ofthe U.S.Eastern Seaboard,is another clades and are distantly related to those known from else-
Distribution: Mesozoic Mammals in Space and Time 61
TABLE 2.15. Albian-Cenomanian Mammals ofthe chapter 8);Bryceomys,otherwise known from the Turon-
Mussentuchit Local Fauna,Utah (see figure 2.10) ian ofUtah,makes its first appearance in this fauna.Also
notable is the first appearance ofNeoplagiaulacidae,in the
Eutriconodonta
form of?Mesodma,a genus otherwise known from Aquilan
Triconodontidae
and younger assemblages in the Late Cretaceous ofNorth
Astroconodon delicatus
Corviconodon utahensis America.The Mussentuchit local fauna includes six boreo-
Jugulator amplissimus sphenidan mammals,four of which are marsupials:Ade-
Multituberculata lodelphys,Kokopellia,Pariadens,and Sinbadelphys(Cifelli,
?“Plagiaulacida,”family incertae sedis 1993a;Cifelli and Muizon,1997;Cifelli,2004).Pariadens,
Ameribaatar zofiae a possible stagodontid,is also known from the Cenoman-
Janumys erebos ian ofUtah (Cifelli and Eaton,1987;Eaton,1993b).Despite
cf.Janumys erebos
the fact that they dominate the therian component of
Gen.et sp.indet.
the Mussentuchit local fauna, marsupials of the Cedar
Cimolodonta,family incertae sedis
Mountain Formation are rare and low in diversity (both
Bryceomys intermedius
taxonomic and morphologic) compared to Campanian–
Bryceomyscf.intermedius
Maastrichtian faunas of North America.Currently,these
Cedaromys bestia
four taxa are the oldest known marsupials.Their primi-
Cedaromyscf.bestia
Cedaromys parvus tiveness,low diversity,and modest morphologic differen-
Cedaromyscf.parvus tiation suggest that they may lie near the base of North
?Paracimexomys perplexus America’s Cretaceous marsupial radiation (Cifelli,2004).
?Paracimexomyscf.perplexus There is as yet no definitive evidence for Eutheria in the
?Paracimexomys robisoni Mussentuchit local fauna, despite their earlier (Aptian–
?Paracimexomyscf.robisoni Albian) presence in North America.Curiously,while the
Neoplagiaulacidae
mammals seem to represent North American clades with
?Mesodmasp.
no obvious close ties to groups known from elsewhere,
Stem Trechnotheria (“symmetrodontans”)
other taxa in the Mussentuchit local fauna, particularly
Spalacotheriidae
dinosaurs, suggest a proximal origin from Asia (Cifelli,
Spalacolestes cretulablatta
Kirkland,et al.,1997).
Spalacolestes inconcinnus
Two footprints attributed to a mammal,Duquettichnus
Spalacotheridium noblei
Family incertae sedis kooli, have been described from the Early Cretaceous of
Gen.et sp.indet. the Peace River Canyon,British Columbia.They are re-
Stem Boreosphenida (“tribotherians”) ported to show syndactyly ofpedal digits II and III,so they
Picopsidae have been referred to the Marsupialia (Sarjeant and Thul-
Gen.et sp.indet. born,1986).Additional tracks from the Gates Formation,
Family incertae sedis Alberta (Albian),are believed to represent several types of
Gen.nov.,sp.A
mammals (Sarjeant,2000).
Gen.nov.,sp.B
Marsupialia
?Stagodontidae LATE CRETACEOUS
Pariadens mckennai
As with the Early Cretaceous,the past two decades have
Family incertae sedis
witnessed a remarkable improvement in the record of
Adelodelphys muizoni
Kokopellia juddi Late Cretaceous mammals.Specimens or faunas are now
Sinbadelphys schmidti known from most major landmasses,Australia and Africa
being the most notable and most unfortunate exceptions.
Advances in knowledge have been particularly welcome
where in the world (Cifelli and Madsen,1998,1999).As from the pre-Campanian,or early Late Cretaceous,part of
many as 15 taxa of multituberculates, collectively repre- the record.Twenty years ago only two known occurrences
sented by more than 1,000 specimens,are known from the —both consisting of practically indeterminate specimens
Mussentuchit local fauna (Eaton and Cifelli,2001).Several from North America—fell within this time interval
may represent surviving “plagiaulacidans.” Most of the (Clemens et al.,1979).Significant early Late Cretaceous
multituberculates ofthe Mussentuchit local fauna belong specimens and faunas are now known from both Asia and
to the Paracimexomysgroup of basal cimolodontans (see North America.
62 DISTRIBUTION: MESOZOIC MAMMALS IN SPACE AND TIME
Eutherians (and, in North America, marsupials) and plex mixed pattern involving both Laurasian and Gond-
multituberculates underwent diversification on the north- wanan elements,some ofwhich may have been inherited
ern continents. Late Cretaceous records now available from earlier faunal continuity ofthe landmasses.
from Western and Central Europe suggest some degree of Champ-Garimond,Gard,France (figure 2.9),yielded
endemicity during this epoch (Ra˘dulescu and Samson, a lower molar first described by Ledoux et al.(1966).Long
1997; Gheerbrant and Astibia, 1999). The existing pre- known as the “Champ-Garimond molar,”the specimen
Maastrichtian record for South America lacks boreo- was formally referred to its own species,Labes garimondi,
sphenidan mammals, which apparently did not arrive by Sigé (in Pol et al.,1992).Labes,also known from the
there until the end of the Cretaceous. Instead, endemic Late Cretaceous (Maastrichtian) of Spain,is believed to
groups or derived members of taxa more typical of the represent a eutherian group that is endemic to Europe and
Jurassic are present (Bonaparte,1990). is related to “zhelestids”ofmiddle Asia (Gheerbrant and
Astibia, 1999). “Zhelestids” are of importance because
WESTERN EUROPE they are believed to be basal members ofthe ungulate ra-
diation (Nessov,Archibald,and Kielan-Jaworowska,1998,
Late Cretaceous mammals of Western Europe are now see chapter 13). More recently collected material from
known from France,Spain,and Portugal (table 2.16).Most Champ-Garimond, including another lower molar, is
sites or occurrences are listed as being of Campanian– mentioned by Pol et al.(1992) and Sigé et al.(1997).
Maastrichtian or Maastrichtian age,with the exception of Work by Emmanuel Gheerbrant and colleagues has re-
Champ-Garimond,France,which is believed to be Cam- sulted in the discovery of two additional Late Cretaceous
panian.As summarized by Le Loeff(1991),Europe during mammal sites in France,both in the Petites Pyrénées (figure
the Late Cretaceous was an archipelago. Of the four 2.9).Barrage Filleit(figure 2.9) is in the Grès de Labarre
major noninundated areas,Late Cretaceous mammals are Formation, which is placed in the upper Campanian to
known from the Ibero-Armorican and Transylvanian lower Maastrichtian.The Barrage Filleit site includes both
landmasses.As a whole,the European fauna shows a com- macrovertebrates and microvertebrates,deposited in a flu-
vial setting.The only mammal specimen is the distal meta-
tarsal ofa primitive eutherian or metatherian (Gheerbrant
TABLE 2.16. Late Cretaceous mammals ofWestern
Europe (see figure 2.9;locality numbers do not correspond et al., 1997). The site of Peyrecave (figure 2.9) is in the
between map and table).Localities:1,Champ-Garimond Marnes d’Auzas Formation,which is upper Maastrichtian.
(Campanian,France);2,Barrage Filleit (Grès de Labarre
It includes paleoenvironments ranging from marginal
Formation,Campanian–Maastrichtian,France);3,
marine to lagoonal to continental, with paleosols and
Peyrecave (Marnes d’Auzas Formation,Maastrichtian,
France);4,Taveiro (Late Cretaceous,Portugal);5,Quintanilla fluvial deposits.Microvertebrates were recovered by screen-
del Coco (Calizas de Lynchus Formation,Maastrichtian, washing and acid-bathing matrix. The Peyrecave site has
Spain);6,Laño (Maastrichtian,Spain)
yielded fragmentary mammal teeth from two levels, the
?Marsupialia1 “marnes rousses”and the “lumachelle à huîtres”(Gheer-
?Alphadontidae brant et al.,1997).
cf.Alphadonsp.(4) A site at the clay quarry ofthe Cerâmica de Montego,
?”Pediomyidae” Taveiro, Portugal (figure 2.9), has yielded five mammal
cf.“Pediomys”sp.(4) teeth or tooth fragments ofLate Cretaceous age (Antunes
Eutheria et al.,1986).An insectivore said to be similar to Leptacodon
?Nyctitheriidae
(otherwise known from the early Tertiary ofNorth Amer-
cf.Leptacodonsp.(4)1
ica and Europe) is present;at least two possible marsupial
?Palaeoryctidae
taxa,one said to be similar to Alphadonand the other to
Gen.et sp.indet.A (5)1
“Pediomys,” have also been reported (Antunes et al.,
Gen.et sp.indet.B (5)1
1986).Both of these are otherwise known only from the
Family incertae sedis
Late Cretaceous ofNorth America and,ifthe records from
Labes garimondi(1)
Labes quintanillensis(5) Taveiro are verified,they will be ofgreat biogeographic in-
?Labessp.(6) terest.Gheerbrant and Astibia (1999) indicate that one of
Lainodon orueetxebarriai(6) the tribosphenic mammals from Taveiro may represent
Lainodonsp.nov.(6) the endemic eutherian clade that includes Lainodonand
Gen.and sp.indet.(2,3) Labes.A report ofa possible “symmetrodontan”from the
site is based on a lower tooth that is now lost.Its identity
1 Occurrences ofextraordinary interest ifconfirmed;presently consid-
ered highly dubious. is not determinable;from the available figure (Antunes et
Distribution: Mesozoic Mammals in Space and Time 63
al.,1986),we tentatively suggest that the tooth represents EASTERN EUROPE
a lower premolar ofa eutherian.
Two other sites on the Iberian Peninsula,both in Spain Only one region in Eastern Europe has thus far yielded
(figure 2.9),have yielded Late Cretaceous mammals.Quin- mammals ofLate Cretaceous age,the Hat‚eg Basin,Roma-
tanilla del Coco, Burgos Province, is in the Calizas de nia (figure 2.16,table 2.17).A useful account ofthe geo-
Lynchus Formation and is reported to be ofMaastrichtian logic setting and microvertebrate fauna in general is given
age (Pol et al.,1992).Three mammals are known from the by Grigorescu et al.(1999).As noted,Europe assumed the
site;two are reported to be possible “palaeoryctid”eutheri- form of an archipelago during parts of the Late Creta-
ans and the third was named as Labes quintanillensis. As ceous.Theropods known from Transylvania are generally
noted earlier, Labes is also known from France and is small,and this seems to be true ofother dinosaurs as well,
thought to be related to Asiatic “zhelestids”and,ultimately, suggesting that the region was,indeed,insular (Weisham-
ungulates (Gheerbrant and Astibia,1994,1999).The site of pel et al., 1991; Csiki and Grigorescu, 1998). Mammals
Laño,in the Basque region,has also yielded at least three are known from five sites in the Hat‚eg Basin.Two are near
mammal taxa, all represented by isolated teeth, through Sînpetru (also called the Sibis¸el Valley) and are in the Sîn-
screenwashing. The stratigraphic unit for the site is not petru Formation.The locality ofDupa˘Râu(figure 2.16)
given, but it lies above a Campanian marine unit and is has yielded an unidentified cimolodontan (Grigorescu,
thought to be late Campanian or early Maastrichtian in age 1984;Grigorescu and Hahn,1987).A partial skull is known
(Astibia et al.,1991;Gheerbrant and Astibia,1999).Lain- from the nearby site of Tamas¸el.Kogaionon ungureanui,
odon orueetxebarriaiis the best-represented member ofthe based on this specimen, is referred to its own family,
fauna,which includes another possible species ofthis genus Kogiaononidae, known only from Europe (Kielan-
and one possibly referable to Labes (Gheerbrant and Jaworowska and Hurum,2001,see chapter 8).Also in the
Astibia,1994,1999).Interestingly,all ofthe mammal spec- Sînpetru Formation,the locality of Pui (figure 2.16),in
imens from this site—and, for that matter, other Late the eastern part of the Hat‚eg Basin, has yielded three
Cretaceous sites of Western Europe—represent therians. multituberculate taxa (Grigorescu et al.,1985;Ra˘dulescu
This is quite unlike the situation encountered in North and Samson, 1986, 1997). The only named species is
America,where there are abundant multituberculates,or in Barbatodon transylvanicum,which is a basal cimolodon-
Romania,where the limited record thus far includes only tan referred to the so-called Paracimexomys group (see
multituberculates. chapter 8).
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bbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbdddddddddddddddddddaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbaaaaaaaaaaaaaaabbbddddddddddddddddddddaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbb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FIGURE 2.16. Late Cretaceous (Maastrichtian) mammal localities in the Hat‚eg Basin,Romania.Localities:1, Pui; 2, Dupa˘ Râu;
3,Tamas¸el(Sînpetru Formation);4,Tus¸tea;5,Fântânele(Densus¸-Ciula Formation).Source:redrawn from an illustration provided by
Z.Csiki.
64 DISTRIBUTION: MESOZOIC MAMMALS IN SPACE AND TIME
TABLE 2.17. Late Cretaceous Mammals ofRomania. leagues.The mammal assemblages of middle Asia (table
Localities (all in the Hat‚eg Basin,Romania;see figure 2.16; 2.18) are noteworthy for several reasons.First,the fossils
locality numbers do not correspond between map and table):
are reasonably complete,including many jaws and,in one
1,Dupa˘ Râu;2,Tamas¸el;3,Pui (Sînpetru Formation,
Maastrichtian);4,Tus¸tea;5,Fântânele (Densus¸-Ciula case,a skull.Second,they sample an important time in-
Formation,Maastrichtian) terval—the early part of the Late Cretaceous, which is
otherwise poorly represented by mammalian fossils.
Multituberculata
Finally,the assemblages are important zoogeographically
Family incertae sedis
(see Nessov,1992).The mammals are quite different from
Barbatodon transylvanicum(3)
those to the east, in the Late Cretaceous of Mongolia,
Gen.et sp.indet.(“ptilodontoid”) (3)
Gen.et sp.indet.(“taeniolabidoid”) (3)1 which are presumed to be arid-adapted and are in this
Gen.et sp.indet.(1,4,5) sense specialized. Among others, the mammal assem-
Kogaionidae blages ofmiddle Asia appear to include primitive relatives
Haininasp.A (5) of ungulates (Archibald,1996b)—eutherians that would
Haininasp.B (5) not flourish or radiate widely until the early Tertiary.
Kogaionon ungureanui(2) Most of the Late Cretaceous mammals of middle Asia—
1 Occurrence ofgreat significance ifconfirmed;presently considered Kazakhstan,Uzbekistan,Tadjikistan,and Kirghizia—are
highly dubious. included in several recent summary papers (Nessov,
Sigogneau-Russell,and Russell,1994;Nessov,1997;Nessov,
Archibald, and Kielan-Jaworowska, 1998; Averianov,
The remaining two sites are in the northwest part ofthe
2000).We review the occurrences in stratigraphic order.
Hat‚eg Basin (see Csiki and Grigorescu, 2000). They are
Three mammal localities are known from the Khod-
both in the Densus¸-Ciula Formation,which is believed to
zhakul Formation, Karakalpakistan, Uzbekistan (figure
be a correlative ofthe Sînpetru Formation.A single inci-
2.11).The mammal localities are in the upper part ofthe
sor of an unidentified cimolodontan is known from the
unit,which is believed to be lower Cenomanian based on
site ofTus¸tea.The Fântânelelocality,west ofTus¸tea and
correlation with a marine regressive phase and on some of
near Va˘lioara,has yielded three multituberculate taxa,two
the lower vertebrate fauna (Averianov,2000).Undescribed
of which are referable to Hainina.This genus appears to
specimens, consisting largely of edentulous jaws of un-
be related to Kogaionon; its occurrence in the Densus˘-
identified therians, are known from the site of Khod-
Ciula Formation is notable because Haininais otherwise
zhakulsay (figure 2.11),which is interpreted to represent
known from the Paleocene of Western Europe (Vianey-
a channel connecting two brackish reservoirs (Nessov,Si-
Liaud,1979,1986).
gogneau-Russell,and Russell,1994).Unidentified mam-
mal remains have also been reported from the Chelpyk
ASIA
locality,which may be slightly higher in the section than
the other sites.Sheikhdzheili,to the northeast of Khod-
Middle Asia
zhakulsay,is the source for three mammals;a large possi-
The vast area ofRussia and adjacent countries formerly ble deltatheroidan and two eutherians,which are among
included in the Soviet Union was long a complete blank the oldest representatives ofthis group.
for Cretaceous mammals.A single specimen ofa Late Cre- A single specimen,belonging to the eutherian Sorlestes
taceous eutherian from Kazakhstan was described by kara,was recovered from a drill core at the Ashikol“lo-
Bazhanov (1972), but it remained for Lev A. Nessov to cality,”east ofthe Ashikol lakes,Chimkent District,Kaza-
more fully exploit middle Asia for fossil mammals in a se- khstan (figure 2.11).The unit for the fossil horizon (500
ries of expeditions beginning in 1978. Nessov must be m underground) is unnamed,but the specimen is believed
given the greatest credit for his remarkable contributions to be at least as old as early Turonian, based on paly-
to knowledge ofearly mammals.His achievements are all nomorphs recovered from an overlying unit (Nessov,
the more impressive in light ofthe harsh field conditions Sigogneau-Russell,and Russell,1994).
and virtual lack ofsupport he endured;among other dif- The vast majority of the mammals known from the
ficulties,his team occasionally had to hitchhike to the field Late Cretaceous ofmiddle Asia are from the Bissekty For-
area and dig 3-m-deep holes to find drinking water (see, mation,Kizylkum Desert,Uzbekistan (figure 2.11).Fossil
e.g., Averianov, 2000). Nessov described more than 25 mammals have been recovered from several horizons in
species ofCretaceous mammals,and part ofthe collection this unit at Dzharakuduk (figure 2.11).The oldest mam-
has not yet been published;research is being continued by mal-yielding level may be late Turonian,based on sharks
Alexander O. Averianov, J. David Archibald, and col- (Nessov, Sigogneau-Russell, and Russell, 1994). Six or
TABLE 2.18. Late Cretaceous Mammals ofRussia and the Commonwealth ofIndependent States (see figure 2.11);locality
numbers do not correspond between map and table).Localities:1,Sheikhdzheili;2,Khodzhakulsay;3,Chelpyk (Karakalpakistan,
Uzbekistan;Khodzhakul Formation,early Cenomanian);4,Ashikol (Chimkent District,Kazakhstan;early Turonian);5,
Dzharakuduk (Kizylkum Desert,Uzbekistan;Bissekty Formation,Turonian);6,Dzharakuduk (Bissekty Formation,Coniacian);
7,Dzharakuduk (Aitym Formation,Santonian);8,Zhalmauz Well (Kyzyl-Orda District,Kazakhstan;Bostobe Formation,
Santonian);9,Kansay (Khodzant District,Tadzhikistan;Yalovach Formation,Santonian);10,Yantardakh (Yakutia,Russia;Khets
Formation,Santonian);11,Grey Mesa (Chimkent District,Kazakhstan;Darbasa Formation,early Campanian)
CENOMANIAN “Zhelestidae”
Mammalia Eoungulatum kudukensis(6)
Family incertae sedis cf.Eoungulatum kudukensis(6)
Gen.et sp.indet.(2,3) Kumsuperus avus(6)
?Deltatheroida Ortalestes tostak(6)
Family incertae sedis Parazhelestes minor(6)
Oxlestes grandis(1) Parazhelestes robustus(6)
Eutheria Sorlestes budan(6)
Otlestidae Zhelestes temirkazyk (6)
Otlestes meiman(1) Gen.et sp.indet.(6)
“Zhelestidae” Family incertae sedis
Eozhelestes mangit(1) Bulaklestes kezbe(6)
TURONIAN Daulestes nessovi(6)
Stem Trechnotheria (“symmetrodontans”) Daulestes kulbeckensis(6)
Spalacotheriidae “Sazlestes tis”(6)
?Shalbaatar bakht(5) SANTONIAN
Eutheria Mammalia
Zalambdalestidae Family incertae sedis
Kulbeckia rara(5) Gen.et sp.indet.(10)
“Zhelestidae” Multituberculata
Aspanlestes aptap(5) Family incertae sedis
Sorlestes kara(4) Uzbekbaatar wardi(7)
Family incertae sedis Eutheria
Daulestes kulbeckensis(5) Zalambdalestidae
Daulestes inobservabilis(5) Kulbeckia kansaica(9)
CONIACIAN ?Zalambdalestidae
Multituberculata Beleutinus orlovi(8)
Family incertae sedis “Zhelestidae”
Uzbekbaatar kizylkumensis(6) Gen.et sp.indet.(7)
Gen.et sp.indet.(6) Family incertae sedis
Deltatheroida Gen.et sp.indet.(8,9)
Deltatheridiidae EARLY CAMPANIAN
Deltatherus kizylkumensis(6) Multituberculata
Sulestes karakshi(6) Family incertae sedis
Sulestessp.(6) Bulganbaatarsp.(11)
Gen.et sp.indet.(6) Deltatheroida
Marsupialia Deltatheridiidae
Asiatheriidae Deltatheridium nessovi(11)
Marsasia aenigma(6) Eutheria
Marsasiasp.(6) Kennalestidae
Eutheria Gen.et sp.indet.(11)
Kennalestidae Zalambdalestidae
?Kennalestes uzbekistanensis(6) Alymlestes kielanae(11)
Sailestes quadrans(6) ?Alymlestessp.(11)
“Nyctitheriidae” “Zhelestidae”
Paranyctoides aralensis(6) ?Aspanlestessp.(11)
Zalambdalestidae
Kulbeckia kulbecke(6)
66 DISTRIBUTION: MESOZOIC MAMMALS IN SPACE AND TIME
more mammals are known from this level.One ofthese, by the oldest reasonably complete skull of a eutherian
Shalbaatar bakht (named but not figured by Nessov, mammal (McKenna et al.,2000).
1997),appears to be a “symmetrodontan”;the remainder Fossil mammals have recently been reported from the
are eutherians,including the “palaeoryctid”-like Daulestes Aitym Formation at Dzharakuduk (Averianov, 1999;
and one of the oldest of the “Zhelestidae”(Aspanlestes), Archibald and Averianov,2001b).This unit,which over-
which are thought to be related to ungulates. lies the Bissekty Formation,is ofprobable Santonian age
A dozen or more localities of Coniacian age have and includes a fauna dominated by marine taxa,including
yielded mammals from the Bissekty Formation at Dzhara- chondrichthyans,plesiosaurs,turtles,and molluscs.Three
kuduk(figure 2.11,table 2.18).For convenience,we treat mammals are known thus far from the Aitym Formation:
them collectively here,though several separate levels are a large eutherian represented by an edentulous jaw frag-
recognized (see Nessov, Sigogneau-Russell, and Russell, ment, an insectivoran Paranyctoides sp., and the multi-
1994;Averianov,2000).Some 25 or more kinds ofmam- tuberculate Uzbekbaatar wardi(known from a p4),which
mals have been reported from these sites.The multituber- may be a descendant ofU.kizylkumensisfrom the Bissekty
culate Uzbekbaatar (see Kielan-Jaworowska and Nessov, Formation (Averianov,1999).
1992) is assigned to Cimolodonta incertae sedis(see chap- Two additional sites ofSantonian age are known from
ter 8).Deltatheroida,a predominantly Old World group middle Asia.Zhalmauz Well,Kyzyl-Orda Province,Kaza-
that may be related to Marsupialia (chapter 12),are repre- khstan (figure 2.11),is in the lower Bostobe Formation,
sented by at least three taxa (Kielan-Jaworowska and with a Santonian correlation based on turtles and chon-
Nessov,1990;Nessov,1997).Ofspecial interest among the drichthyans (Averianov, 2000). Beleutinus orlovi, de-
fauna is Marsasia, which appears to be a true marsupial scribed from this site by Bazhanov (1972),may be related
and thus is the earliest representative ofthat group in Asia to a peculiar eutherian group known from Mongolia,the
(Averianov and Kielan-Jaworowska, 1999). Marsupialia Zalambdalestidae (Nessov, Sigogneau-Russell, and Rus-
had long been thought to be of North American origin, sell, 1994). The only other mammal specimen known
not reaching the Old World until the Tertiary. Asia- from this site is a large, unidentifiable cervical vertebra
therium,mentioned later,and Marsasiachallenge this in- (Nessov and Khisarova,1988).The Kansaysite,Khodzant
terpretation and suggest a much earlier presence in Asia District,Tadzhikistan (figure 2.11),has also yielded two
than previously envisaged (see chapter 12).Some of the mammal specimens.The occurrences are in the Yalovach
dentally primitive eutherians from the Coniacian of Formation,believed to be early Santonian on the basis of
Dzharakuduk also have interesting biogeographic impli- fishes and turtles (Nessov,Sigogneau-Russell,and Russell,
cations. One is possibly referable to Kennalestes, known 1994).The only described mammal from Kansay is Kul-
from the Campanian ofMongolia;another,Paranyctoides beckia kansaica(see Nessov,1993);this genus is also rep-
aralensis,belongs to an insectivoran genus otherwise re- resented in older horizons (Turonian and Coniacian,Bis-
stricted to the Campanian–Maastrichtian ofNorth Amer- sekty Formation) ofmiddle Asia.
ica (Fox,1979d,1984b; Cifelli,1990e; see detailed treat- Another Santonian mammal occurrence, well out of
ment by Archibald and Averianov, 2001b). Most of the the region under discussion but mentioned here for con-
eutherians from the Coniacian of Dzharakuduk are re- venience,is in the Khets Formation at Yantardakh,Siberia
ferred to the “Zhelestidae.” These are especially note- (not figured).The specimen consists ofmammalian hair
worthy because they are believed to be related to ungulates embedded in amber,and is notable for its high (70° N)
(Archibald, 1996b; Nessov, Archibald, and Kielan- paleolatitudinal occurrence (Nessov, Sigogneau-Russell,
Jaworowska,1998).As such,they represent the most com- and Russell,1994).
pelling evidence for early Late Cretaceous radiation of a The youngest Late Cretaceous mammals of middle
modern placental group (Archibald,1999).Additionally, Asia are from Grey Mesa,near the Alymtau Range,Kaza-
most eutherian groups from the Cretaceous of Asia lack khstan. The mammals, including some six taxa, come
obvious ties with more recent taxa,particularly those from from the lower part of the Darbasa Formation,which is
North America (Novacek et al.,1997;Cifelli,1999a).These believed to be early Campanian (Nessov,1993;Averianov
ungulate-like “zhelestids”are the best known exception to and Nessov,1995;Averianov,2000).The fauna is thus im-
this rule and thus provide a viable source for the later ra- portant because it is close to the age of the oldest Late
diation of ungulates in North America. A final note- Cretaceous mammals known from Mongolia,which oc-
worthy occurrence in the Coniacian of Dzharakuduk is cur in the Djadokhta Formation and presumed equiva-
that ofDaulestes nessovi(the genus is also known from the lents.Two genera,the multituberculate Bulganbaatarand
Turonian part ofthe Bissekty Formation),which is known the deltatheroidan Deltatheridium, are also known from
Distribution: Mesozoic Mammals in Space and Time 67
the Djadokhta Formation,and the placental families Ken- Cretaceous mammal sites and specimens,not a single rea-
nalestidae and Zalambdalestidae are also represented in sonably complete skull ofthis age has yet been published
both the Grey Mesa and Mongolian faunas (see Averianov from anywhere on the continent. The extraordinary
and Nessov,1995;Averianov,1997,2000;Archibald et al., preservation ofthe Mongolian specimens is due to an un-
2001). usual depositional setting characterized by arid condi-
tions and extensive dune systems (see later).
Mongolia
Initial discoveries in Late Cretaceous strata ofthe Gobi
Without doubt,the best known ofall Mesozoic mam- Desert were made in the 1920s by the Central Asiatic Ex-
mals come from the Late Cretaceous ofthe Gobi Desert, peditions of the American Museum of Natural History,
Mongolia (table 2.19).Skulls and,commonly,articulated led by Roy Chapman Andrews (see informative and read-
skeletons are the rule,and isolated fragments the excep- able account by Andrews,1932).The major fossil area for
tion.This is in stark contrast with the record from the Late Late Cretaceous mammals (e.g., Gregory and Simpson,
Cretaceous of North America (and virtually everywhere 1926;Simpson,1928d) and dinosaurs discovered by these
else),where fossils generally consist of jaw fragments or expeditions is near the so-called Flaming Cliffs,at a place
isolated teeth,usually recovered through screenwashing. then called Shabarakh Usu and now termed Bayan Zag
Indeed, though North America boasts many more Late (spelled Bayn Dzak in most recent literature).The fossil-
TABLE 2.19. Late Cretaceous Mammals ofMongolia,China,and Japan (see figures 2.4,2.17;locality numbers do not correspond
between maps and table).Localities or local faunas:1,Bayan Zag (Djadokhta Formation,Campanian);2,Tögrög (Tögrög Beds,
equivalent ofthe Djadokhta Formation,Campanian);3,Ukhaa Tolgod (“Ukhaa Tolgod Beds,”not formally named ,Campanian);
4,Khulsan (Baruungoyot Formation,Campanian);5,Nemegt (Baruungoyot Formation,Campanian);6,Hermiin Tsav (Red Beds
ofHermiin Tsav,Campanian);7,Udan Sayr (unnamed unit,Campanian);8,Khaichin Uul (?Nemegt Formation,?Maastrichtian);
9,Guriliin Tsav (?Nemegt Formation,?Maastrichtian),Mongolia;10,Tsondolein-Khuduk,Gansu,China (unit uncertain;
?Cenomanian);11,Bayan Mandahu,Inner Mongolia,China (Bayan Mandahu Formation,Campanian);12,Amagimi Dam,
Kiyushu,Japan (“Upper Formation”ofthe Mifune Group,late Cenomanian or early Turonian)
Multituberculata Deltatheroides cretacicus(1)
Family incertae sedis Khuduklestes bohlini(10)
Bulganbaatar nemegtbaataroides(1) Gen.et sp.nov.(9)
Bulganbaatarcf.nemegtbaataroides(3) Marsupialia
Chulsanbaatar vulgaris(4,5,6) Asiatheriidae
Chulsanbaatarcf.vulgaris(3) Asiatherium reshetovi(7)
Nemegtbaatar gobiensis(3,4,5,6) Eutheria
Gen.nov.,sp.A (3) Family incertae sedis
Gen.nov.,sp.B (3) Hyotheridium dobsoni(1)
?Cimolomyidae cf.Hyotheridiumsp.(3)
Buginbaatar transaltaiensis(8) Asioryctidae
Djadochtatheriidae Asioryctes nemegetensis(4,5,6)
Catopsbaatar catopsaloides( 4,6) cf.Asioryctessp.(3)
Djadochtatherium matthewi(1,2,11) Ukhaatherium nessovi(3)
?Djadochtatherium matthewi(3) Kennalestidae
Kryptobaatar dashzevegi(1,2,3,6) Kennalestes gobiensis(1)
Kryptobaatar mandahuensis(11) Kennalestescf.gobiensis(3)
Tombaatar sabuli(3,?11) Kennalestessp.(11)
Sloanbaataridae Zalambdalestidae
Kamptobaatar kuczynskii(1) Barunlestes butleri(5,6)
Kamptobaatarcf.kuczynskii(3) Zalambdalestes lechei(1,2,3)
Nessovbaatar multicostatus(6) Zalambdalestessp.(11)
Sloanbaatar mirabilis(1) “Zhelestidae”
Sloanbaatarcf.mirabilis(3) Sorlestes mifunensis(12)
Deltatheroida
Deltatheridiidae
Deltatheridium pretrituberculare(1,3,6)
68 DISTRIBUTION: MESOZOIC MAMMALS IN SPACE AND TIME
yielding unit is the Djadokhta Formation.This unit and the excellent summaries of Gradzin´ski et al. (1977),
many other geographic and stratigraphic terms of the Jerzykiewicz and Russell (1991),and Jerzykiewicz (1995).
region are variously spelled and referenced (see, e.g., Correlation ofthe Upper Cretaceous strata ofthe Gobi
Gradzin´ski et al.,1968;Gradzin´ski and Jerzykiewicz,1974; Desert with vertebrate sequences from elsewhere is also
Novacek et al., 1994). Polish-Mongolian Expeditions problematic. Marine strata are lacking, so that it is not
(1963–1971), led by Zofia Kielan-Jaworowska, worked possible to establish correlation on the basis of standard
these exposures and discovered many additional fossils at marine stages. Similarly, there are currently no radio-
Bayan Zag and at some nearby newer sites.They also dis- metric,paleomagnetic,or other data to establish a chrono-
covered a number ofother exposures,most notably those stratigraphic framework.Historically,age estimates have
to the west ofthe Nemegt Basin.These are significant in varied widely—with the Djadokhta mammals,for exam-
that they include mammals from younger horizons—the ple,being considered as old as Cenomanian or as young as
Baruungoyot Formation and its presumed equivalents Tertiary (see the excellent summary and references cited
(see,e.g.,Jerzykiewicz and Russell,1991).Fossil mammals by Lillegraven and McKenna,1986).Comparisons based
collected by the Polish-Mongolian Expeditions have been on the vertebrates themselves are fraught with difficulty
described in a long list ofpublications,most ofwhich are because the Mongolian taxa are arid adapted and highly
cited later.The region was also worked by Soviet-Mongo- endemic (see,e.g.,Osmólska,1980).Based on the stage of
lian Expeditions,mainly in the late 1960s and 1970s (see evolution (e.g., Fox, 1978) and inferred climatological
review by Kurochkin and Barsbold,2000).New sites for changes in the sequence (Jerzykiewicz and Russell,1991),
Late Cretaceous mammals were discovered but, to our we follow Lillegraven and McKenna (1986) in considering
knowledge,specimens from only three ofthese have been the faunas ofthe Djadokhta and Baruungoyot formations
published (see Kielan-Jaworowska and Sochava, 1969; to correlate with the Campanian.We also tentatively ac-
Kielan-Jaworowska and Nessov, 1990; Szalay and Trofi- cept the early Campanian age for the Djadokhta and late
mov,1996).Several other institutions have sent field par- Campanian for the Baruungoyot Formation.Similarity in
ties to the Gobi Desert in search ofLate Cretaceous mam- the mammalian assemblages of the Djadokhta and Dar-
mals, the most notable of these being the current basa (Kazakhstan,discussed earlier) formations led Averi-
American Museum–Mongolian Academy Expeditions, anov (1997) to propose a lower Campanian correlation for
which began in 1990. The most significant discovery of the Djadokhta Formation.This correlation would imply
these expeditions to date is a new locality,Ukhaa Tolgod, that the Baruungoyot Formation is also ofearly Campan-
in the Nemegt Basin, where literally hundreds of skulls ian or,more probably,late Campanian age.The Nemegt
and,in many cases,associated skeletons were discovered Formation is generally considered to be Maastrichtian,
(Dashzeveg et al.,1995).The assemblage,which includes perhaps middle Maastrichtian (Jerzykiewicz and Russell,
a few previously unknown taxa (Novacek et al., 1997; 1991),in age.
Rougier et al.,1997,see also Wible and Rougier,2000),ap- The stratotype ofthe Djadokhta Formation is at Bayan
pears to be similar to that ofthe Djadokhta Formation,al- Zag (see Gradzin´skiet al.,1977) in the Ulan Nur Basin.The
though it also contains the elements previously known unit consists mainly of fine poorly cemented and mostly
only from the Baruungoyot Formation and its equivalent aeolian sandstones with interbedded conglomerates and
the Red Beds ofHermiin Tsav (see later). caliche horizons.The depositional environment is inter-
The Gobi Basin includes three major subbasins.For the preted to have included extensive dune systems with spo-
Upper Cretaceous rocks,syndepositional block faulting, radic and ephemeral lakes and the occasional development
discontinuous sedimentation, lack of laterally extensive ofarid paleosols (see,e.g.,Loope et al.,1998).The Baruun-
marker horizons,and discontinuity ofexposures,among goyot Formation was defined on the basis ofexposures at
other features,make lithostratigraphic correlation among Khulsan in the Nemegt Basin,nearly 200 km west ofBayan
geographically widespread fossil localities problematic. Zag (Gradzin´ski and Jerzykiewicz, 1974). Its superposi-
Three units are central to a discussion ofthe Late Creta- tional relationship with the Djadokhta Formation cannot
ceous fossil vertebrate sequence in the Gobi Desert (lower be determined directly.The lower boundaries ofboth units
to higher):the Djadokhta,Baruungoyot,and Nemegt for- are covered in their type areas;the Djadokhta is overlain
mations.The type area ofeach unit includes one or more unconformably by Tertiary rocks (Khashaat,or “Gashato”
localities with significant assemblages offossil vertebrates. Formation), whereas the Cretaceous Nemegt Formation
Correlation offossiliferous strata outside the type areas is overlies the Baruungoyot. However, the Djadokhta For-
based on similarity in lithology,inferred depositional fa- mation is generally believed to be lower,at least in part,
cies,fauna,and other considerations.We refer readers to than the Baruungoyot Formation (contraDashzeveg et al.,