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Stratigraphy and fossil assemblages of the Upper Cretaceous System in the Makarov area, southern Sakhalin, Russian Far East

Authors:
  • University of the Philippines – Diliman
Introduction
A continuous succession of the Cretaceous
Yezo Group is well exposed along the middle
course of the Makarova River and four of its
tributaries: the Victoria R., the Rechitsa R., the
Acacia R., and the Grudzovka R. (Figs. 1, 2).
As in the Naiba section, it is worthy of con-
sideration as one of the reference sections for
Cretaceous stratigraphy in Sakhalin. The re-
Stratigraphy and Fossil Assemblages of the Upper Cretaceous System in
the Makarov Area, Southern Sakhalin, Russian Far East
Haruyoshi Maeda1, Yasunari Shigeta2, Allan Gil S. Fernando3and Hisatake Okada3
1Department of Geology and Mineralogy, Graduate School of Science, Kyoto University,
Kitashirakawa-Oiwake-cho, Sakyou-ku, Kyoto 606–8502, Japan
E-mail: maeda@kueps.kyoto-u.ac.jp
2Department of Geology and Paleontology, National Science Museum, 3–23–1
Hyakunin-cho, Shinjuku-ku, Tokyo 169–0073, Japan
E-mail: shigeta@kahaku.go.jp
3Department of Earth and Planetary Sciences, Graduate School of Science,
Hokkaido University, N10 W8 Kita-ku, Sapporo 060–0810, Japan
E-mail: agsfernando@yahoo.com; oka@ep.sci.hokudai.ac.jp
Abstract The stratigraphy and paleontology of the Cretaceous Yezo Group in the Makarov area has
been thoroughly investigated. Exposures of the group in this area range in age from Santonian to
Maastrichtian, and attain a total thickness of 2,500m. The group is divided into the Bykov and Kras-
noyarka formations in ascending order. The Bykov Formation consists mostly of offshore mudstones,
and is lithologically subdivided into four lithostratigraphic units designated as B1–B4, while the
Krasnoyarka Formation is composed mainly of nearshore sandstones and deltaic deposits, and is sub-
divided into five units: K1–K4b.
Except for the uppermost part of the Krasnoyarka Formation, the remaining Cretceous strata are
very fossiliferous. Among the fossil fauna, pachydiscid, tetragonitid, and gaudryceratid ammonoids
are especially abundant. Sphenoceramus schmidti, of Middle Campanian age, also occurs frequently,
and forms the characteristic S. schmidti Zone, which is widely traceable throughout the area. It is
noteworthy that a nearly complete faunal succession of Campanian and Maastrichtian age can be con-
tinuously observed even though internationally recognized, stage-diagnostic taxa are few.
The relatively uniform sedimentary features of the mudstone deposits as well as the faunal com-
position of the Yezo Group are similar throughout southern Sakhalin and Hokkaido. Although the
datum planes of a few fossil zones extend across some lithostratigraphic boundaries, almost identical
lithofacies and biofacies extend over 1,200km in a north to south direction. Such depositional and
faunal uniformity, which reflects the marine environment in the North Pacific during this portion of
Upper Cretaceous time, is a remarkable characteristic of the Yezo Group.
Twenty-five species of ammonoids, distributed among fourteen genera, are described, two of
which, Hypophylloceras (Neophylloceras) victriense and Gaudryceras makarovense, are new species.
Key words: ammonoids, Makarov, Sakhalin, stratigraphy, Upper Cretaceous
The Cretaceous System in the Makarov Area, Southern Sakhalin, Russian Far East,edited by Y. Shigeta and H. Maeda,
National Science Museum Monographs, 31: 25–120, 2005
gional geology of the area has already been
outlined, and Cretaceous megafossils have
been partly described by previous authors
(Sasa & Koiwai, 1960; Vereshchagin 1970,
1977; Salnikova, 1980; Poyarkova 1987;
Zonova et al., 1993; Yazikova, 1994 etc.).
In order to achieve precise stratigraphic cor-
relation between Sakhalin and Hokkaido, a
Japanese–Russian Joint Research Program
was begun in 1990 (Kodama et al., 2000,
2002). Scientific expeditions to the Makarov
area were successfully carried out by geolo-
gists from both countries in 1993, 1994 and
1996. Utilizing satellite photography for de-
tailed mapping, we investigated distinctive
sedimentary features of the Cretaceous se-
quence, and carefully observed modes of fossil
occurrence as well as the biostratigraphy of
megafossils.
In an effort to investigate calcareous nanno-
fossil biostratigraphy, we have examined a
total of 31 samples (001 to 031) (Appendices
6, 7; locality maps). Smear slides were pre-
pared from the samples and examined under a
light microscope using both cross-polarized
light and phase contrast methods at 1,000
magnification. In order to determine the rela-
tive abundance of species, more than 350
fields of view (FOV) were observed per sam-
ple. Relative abundance categories were adapt-
ed from Bown et al. (1998) and Burnett
(1998). Additional FOVs were observed to
check for the presence of rarely occurring, but
biostratigraphically important species.
The results of the field survey and laborato-
ry investigations as well as pertinent discus-
sions are included in this paper.
Repository of specimen:The following ab-
breviations are used to indicate fossil reposito-
ries: NSM, National Science Museum, Tokyo;
DGMKU, Department of Geology and Miner-
alogy, Kyoto University, Kyoto. Smear slides
26 Haruyoshi Maeda et al.
Fig. 1. Map showing the study area in the Makarov area, southern Sakhalin.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 27
Fig. 2. Satellite photograph of the Makarov area, southern Sakhalin.
and original digital images of calcareous nan-
nofossils are stored at Hokkaido University.
All fossils and samples utilized herein were
collected during the field expeditions and were
transported from Russia to Japan with permis-
sion from the Russian Government, the State
Government of Sakhalin, and other concerned
authorities.
Geologic setting
In general, the Cretaceous System dips
20–45° west, and its strike varies between a
N–S direction and N30°E. It is in fault contact
with Neogene volcaniclastic deposits in the
eastern part of the area, and is unconformably
overlain by Paleogene coal measures in the
west (see satellite photography). A few diorite
sills, extending in a N–S direction, intrude into
the Cretaceous mudstone (Locs. MK2002,
3001, 5003; Fig. 3). At a few localities in the
western part of the area, Cretaceous strata are
repeatedly exposed by fault displacement and
folding. However, such tectonic influences are
generally slight, and continuous successions
are easily observable (Appendices 1–8; route
maps).
Stratigraphy
In the Makarov area, the Cretaceous System
is stratigraphically equivalent to the Yezo
Group (Supergroup) in Hokkaido, Japan. The
group is generally represented by an extremely
thick clastic marine sequence, which can be
interpreted as having been deposited in a fore-
arc basin (Okada, 1979, 1983).
Although only the upper part of the group is
exposed in the Makarov area, it exceeds
2,500m in thickness, and is lithologically sim-
ilar to sediments of the stratotype section in
the Naiba area. It is similarly divided into the
Bykov and Krasnoyarka formations in ascend-
ing order. (Figs. 3–6).
Bykov Formation (Vereshchagin, 1961)
Only the uppermost part of the Bykov For-
mation is exposed in the Makarov area. It con-
sists mainly of monotonous mudstone and is
subdivided into lithostratigraphic units desig-
nated as B1–B4.
Stratotype:Naiba area, southern Sakhalin
(see Matsumoto 1942d, 1954; Zakharov et al.,
1984; Poyarkova, 1987; Kodama et al., 2002).
B1 Unit
Exposures:Middle course of the Makaro-
va River.
Thickness:Greater than 100m.
Stratigraphic relationship:The basal part
is not exposed. The B1 Unit conformably un-
derlies the B2 Unit.
Lithology:The B1 Unit consists of dark
gray, massive, fine mudstone. Its detailed sedi-
mentological features are uncertain because of
poor exposures.
Megafossils:A few lenticular calcareous
nodules were observed in the mudstone but no
megafossils were found in the Makarov area.
In the Lesnaya area, which is about 8km south
of the Makarov area, Damesites sp., Tetrago-
nites glabrus (Jimbo), and Gaudryceras
denseplicatum (Jimbo) occur in calcareous
nodules which are derived from mudstone in
the B1 Unit. This ammonoid assemblage is of
Coniacian or Santonian age.
B2 Unit
Exposures:Loc. MK5002, along the lower
course of the Rechitsa River (typical section);
lower course of the Gruzdovka River.
Thickness:20–60m.
Stratigraphic relationship:The B2 Unit
conformably overlies the B1 Unit, and con-
formably underlies the B3 Unit.
Lithology:The B2 Unit consists of light
gray, massive, fine to medium-grained, thickly
bedded sandstone. Unlike the sandstones of
the Krasnoyarka Formation, the sandstones of
the B2 Unit contain few volcanic fragments.
The unit extends laterally over adjacent
28 Haruyoshi Maeda et al.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 29
Fig. 3. Geological map of the Makarov area, southern Sakhalin.
areas. In the Lesnaya area, the sandstones of
the B2 Unit coarsen and display slumping
structures.
The B2 Unit is often intruded by diorite
sills. The contact between the diorite and sand-
stone is distinct and a thin chilled margin
about 1cm thick, can be observed (Loc.
MK2002).
Megafossils:No fossils were found in the
B2 Unit.
B3 Unit
Exposures:Locs. MK2005–2008 along
the lower course of the Acacia River (typical
section); lower course of the Victoria R. and
Rechitsa R.
Thickness:600m.
Stratigraphic relationship:At Loc. MK-
2003 along the Acacia River, the basal part of
the unit is in direct contact with an intruded
diorite sill. At other localities, the B3 Unit
conformably overlies the B2 Unit and con-
formably underlies the B4 Unit.
Lithology:The B3 Unit consists mainly of
dark gray, intensely bioturbated, fine mud-
stone. Laminations or bedding planes are bare-
ly observable in the mudstone. Poorly sorted
sandstone beds varying in thickness from 10
to 30cm are occasionally intercalated, and the
thinner beds are usually mottled and penetrat-
ed by burrows. Ellipsoidal calcareous nodules,
30–60cm diameter, are commonly embedded
in the mudstone.
At Loc. MK2003, mudstone beds adjacent
to the contact plane with a diorite sill are horn-
felsed.
Microfossils:Repagulum parvidentatum
(Deflandre and Fert), Prediscophaera ar-
khangelskyi
(Reinhardt) and Biscutum mag-
num Wind and Wise occur rarely in the upper
part of the B3 Unit (Figs. 7, 8; Table 1).
Megafossils:Many ammonoids and inoce-
ramids are found in ellipsoidal calcareous nod-
ules as well as in the host mudstone (Table 2),
but the faunal components change stratigraph-
icaly within the unit. Menuites naumanni
(Yokoyama) (Fig. 11) is common in the upper
part, while Eupachydiscus haradai (Jimbo)
and Sphenoceramus orientalis (Sokolov) (Fig.
16) are abundant in the uppermost part. Usual-
ly, these pachydiscids are adult macroconchs
that attain a diameter of 30cm.
In addition, Tetragonites glabrus (Fig. 42)
and Gaudryceras striatum (Jimbo) (Fig. 25) as
well as plant remains are common in the cal-
careous nodules in the uppermost part.
B4 Unit
Exposures:Locs. MK2009–2014 along
the lower course of the Acacia River (typical
section); lower course of the Victoria R., Re-
chitsa R., and Gruzdovka R.
Thickness: 300–400m.
Stratigraphic relationship:The B4 Unit
conformably overlies the B3 Unit, and con-
formably underlies the Krasnoyarka Forma-
tion.
Lithology:The unit consists mainly of
dark gray, intensely bioturbated, massive or
mottled sandy mudstone interbedded with
white vitric tuff layers that vary in thickness
from 5–20cm. Usually, the basal beds are not
exposed, but the more resistant main part
of the unit is well exposed. Several shell-
beds comprised of Sphenoceramus schmidti
(Michael) are intercalated in the lower part of
the unit (Loc. MK2009). The S. schmidti
Zone, consisting of such composite type shell-
30 Haruyoshi Maeda et al.
Fig. 4. Lithological symbols in columnar sections
(Figs. 5, 6, 19).
Stratigraphy of the Upper Cretaceous System in the Makarov Area 31
Fig. 5. Columnar sections of the Cretaceous Yezo Group at four major localities in the Makarov area. Shaded
part in the B4 Unit represents the traceable Sphenoceramus schmidti Zone.
32 Haruyoshi Maeda et al.
Fig. 6. Lithology and faunal succession of the Cretaceous deposits along the Acacia River.
beds (Ando & Kondo, 1999), attains a thick-
ness of 100m, and is traceable throughout the
Makarov area.
Richly fossiliferous spherical and lenticular
calcareous nodules, 30–60cm in diameter, are
common particularly in the upper part of the
unit.
Microfossils:Reinhardtites anthophorus
(Deflandre), R. levis Prins and Sissingh and
Arkhangelskiella cymbiformis Vekshina occur
rarely in the B4 Unit (Figs. 7, 8; Table 1). Cal-
careous nannofossil assemblages are few and
their respective abundance values are general-
ly very low. Their preservation is poor to mod-
erate. With the exception of three samples
(008, 009 and 013) that contain a few Repagu-
lum parvidentatum, nannofossil abundance
values are less than 10 specimens per 100
FOV.
Megafossils:The entire unit is fossilifer-
ous (Table 2). In the lower part, Sphenocera-
mus schmidti (Figs. 17, 18) is abundant in cal-
careous nodules as well as in the surrounding
sandy mudstone. Specimens of S. schmidti,
20–50cm in length, are typically preserved
with their valves in the closed position, and
are embedded horizontally in the intensely
bioturbated, sandy mudstone. Some specialists
argue for taxonomic division of the S. schmidti
group (e.g., Michael, 1899; Nagao & Matsu-
Stratigraphy of the Upper Cretaceous System in the Makarov Area 33
Table1. List of calcareous nannofossils from the Bykov Formation along the Acacia River. Relative abundance cate-
gories were adopted from Bown et al. (1998) and Burnett (1998). F (few): 1 specimen/2–50 FOV. R (rare): 1
specimen/50 FOV.
B3 Unit B4 Unit
Species 001 002 003 004 005 006 007 008 009 010 011 012 013 014 015
Reinhardtites anthophorus (Deflandre) R R
Reinhardtites levis Prins & Sissingh R
Staurolithites zoensis Burnett R R
Tranolithus orionatus (Reinhardt) R
Zeugrhabdotus praesigmoides Burnett R
Zeugrhabdotus spiralis (Bramlette & Martini) R
Zeugrhabdotus trivectis Bergen R R
Chiastozygus litterarius (Górka) R
Chiastozygus synquadriperforatus Bukry R
Chiastozygus sp. A R
Eiffellithus eximius (Stover) R
Eiffellithus turriseiffelii (Deflandre) R
Helicolithus trabeculatus (Górka) R
Cribrosphaerella ehrenbergii (Arkhangelsky) R
Biscutum coronum Wind & Wise R
Biscutum ellipticum (Górka) R R R
Biscutum magnum Wind & Wise R
Discorhabdus ignotus (Górka) R R R
Prediscophaera arkhangelskyi (Reinhardt) R R
Prediscospaera cretacea (Arkhangelsky) R R
Prediscospaera grandis Perch-Nielsen R
Prediscophaera incohatus (Stover) R
Cyclagelosphaera rotaclypeata Bukry R
Watznaueria barnesae (Black) R R R
Watznaueria spp. R R R R
Arkhangelskiella cymbiformis Vekshina R R
Repagulum parvidentatum (Deflandre & Fert) R R R F F R R R F
Braarudosphaera bigelowii (Gran & Braarud) R
Micula staurophora (Gardet) R R
34 Haruyoshi Maeda et al.
Fig. 7. Optical micrographs of calcareous nannofossils under cross-polarized light from the B3 and B4 units,
Bykov Formation, along the Acacia River. Scale bar1
m
m. 1–3, Arkhangelskiella cymbiformis Vekshina,
sample 013. 4, Biscutum coronum Wind and Wise, sample 008. 5, Braarudosphaera bigelowii (Gran and
Braarud), sample 008. 6, Chiastozygus litterarius (Górka), sample 013. 7, Chiastozygus synquadriperforatus
Bukry, sample 013. 8–9, Chiastozygus sp. A, sample 013, a species of Chiastozygus with a small cross super-
imposed over the symmetrical, central cross. The arms of the smaller cross are approximately half as long and
appear to be parallel to the arms of the larger cross. 10, Cyclagelosphaera rotaclypeata Bukry, sample 005. 11,
Eiffellithus eximius (Stover), sample 005. 12, Helicolithus trabeculatus (Górka), sample 013. 13, Micula stau-
rophora (Gardet), sample 008. 14–15, Prediscosphaera arkhangelskyi (Reinhardt), sample 005. 16, Predis-
cosphaera cretacea (Arkhangelsky), sample 013.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 35
Fig. 8. Optical micrographs of calcareous nannofossils under cross-polarized light from the B4 Unit, Bykov For-
mation, along the Acacia River. Scale bar1
m
m. 1, Prediscosphaera grandis Perch-Nielsen, sample 013. 2–3,
Reinhardtites anthophorus (Deflandre), sample 013. 4–5, Reinhardtites levis Prins and Sissingh, sample 013.
6–7, Repagulum parvidentatum (Deflandre and Fert), sample 013. 8–9, Staurolithites zoensis Burnett. 8, sam-
ple 013. 9, sample 008. 10, Tranolithus orionatus (Reinhardt), sample 013. 11–12, Watznaueria barnesae
(Black). 11, sample 008. 12, sample 013. 13, Zeugrhabdotus praesigmoides Burnett, sample 008. 14, Zeu-
grhabdotus spiralis (Bramlette and Martini), sample 013. 15–16, Zeugrhabdotus trivectis Bergen, sample 013.
moto, 1940; Tanabe, 1973; Zonova et al., 1993
etc.), but we regard S. schmidti as one, highly
variable species.
In the lower part of the S. schmidti Zone,
morphotypes occur with diagnostic divergent
ribs that are typical for the adult stage. In con-
trast, smooth morphotypes, in which divergent
ribs appear only in the early growth stage, be-
come dominant in the upper part of the zone
(discussed later). Canadoceras kossmati Ma-
tsumoto (Fig. 12) is also abundant in this hori-
zon. The lowermost shell bed is intercalated in
predominately sandy matrix and yields Gigan-
tocapulus giganteus (Schmidt) (Locs. MK-
3003, 4005; Fig. 17). This species is restricted
to the basal part of the zone with the divergent
ribbed morphotypes of S. schmidti.
Krasnoyarka Formation (Vereshchagin, 1961)
Stratotype:Naiba area, southern Sakhalin
(see Matsumoto 1942d, 1954; Zakharov et al.,
1984; Poyarkova, 1987; Kodama et al., 2002).
The Krasnoyarka Formation consists mainly
of various types of sandstone as well as sandy
mudstones, and is divided into four lithostrati-
graphic units (K1–K4), which become pro-
gressively finer in an ascending sequence ex-
cept for the K4. The formation conformably
overlies the Bykov Formation, but the top por-
tion is cut by a fault, and is not exposed in the
area.
36 Haruyoshi Maeda et al.
Table2. List of ammonids, inoceramids and other invertebrates from the Bykov Formation in the Makarov area.
Species B3 Unit B4 Unit
Ammonoids
Phyllopachyceras ezoense (Yokoyama) 2062 2015
Gaudryceras striatum (Jimbo) 2062
Gaudryceras mamiyai Matsumoto & Miyauchi 2009
Gaudryceras cf. mamiyai Matsumoto & Miyauchi 2015
Anagaudryceras nanum Matsumoto 2062
Tetragonites glabrus (Jimbo) 2062
Tetragonites popetensis Yabe 4004, 2015
Baculites sp. 2015
Damesites cf. sugara (Forbes) 2062
Eupachydiscus haradai (Jimbo) 2062, 4049, 4102
Menuites naumanni (Yokoyama) 2008, 4508, 4515, 5014,
5015, 5020
Canadoceras kossmati Matsumoto 2009, 2010, 2011, 2012, 2014,
2015, 3012, 3013, 4001, 4002,
4003, 4004, 4007, 4008, 4009,
4112, 5035, 5036
Inoceramids
Sphenoceramus nagaoi (Matsumoto & Ueda) 2008
Sphenoceramus orientalis (Sokolov) 2062, 4049, 4101, 4102,
4103
Sphenoceramus schmidti (Michael) 2009, 3003, 3006, 3007, 3008,
3009, 3010, 4000, 4001, 4002,
4003, 4004, 4005, 4006, 4007,
4103, 4104, 4105, 4106, 4107,
4108, 4109, 4110, 4112, 4115,
5026, 5029, 5030, 5033, 5035
Gastropods
Anisomyon cassidarius (Yokoyama) 2008
Gigantocaplustransformis (Dundo) 2062, 4102
Gigantocaplus giganteus (Schmidt) 2009, 3003, 4000, 4001, 4005,
4006, 4104, 5026, 5029
K1 Unit
Exposures:Locs. MK2014–2019 along the
middle course of the Acacia R. (typical sec-
tion); middle course of the Victoria R.,
Rechidtsa R., and Gruzdovka R.
Thickness: 250–270m.
Stratigraphic relationship:The K1 Unit
conformably overlies the B4 Unit of the Bykov
Formation, and conformably underlies the K2
Unit.
Lithology:The lowermost part of the K1
Unit consists of greenish gray, intensely bio-
turbated or mottled muddy sandstone, which
contains many large calcareous concretions
(Loc. MK2014; Fig. 9). It grades upward into
greenish gray, dark poorly sorted, coarse,
sandstone interbedded with gray, mottled,
sandy mudstone in the main part of the K1
Unit (Locs. MK2014–2019). The sandstone
varies in thickness from 50 to 500cm, and is
rich in andesitic volcanic rock fragments. Phy-
cosiphon occurs in the sandy mudstone as well
Stratigraphy of the Upper Cretaceous System in the Makarov Area 37
Table3. List of ammonoids, inoceramids and other invertebrates from the Krasnoyarka Formation in the Makarov area.
Species K1 Unit K2 Unit K3 Unit
Ammonoids
Hypophylloceras victriense sp. nov. 4016, 4018
Hypophylloceras cf. nera (Forbes) 4016
Gaudryceras crassicostatum (Jimbo) 2014
Gaudryceras tombetsense Matsumoto 2022, 4014, 4015
Gaudryceras cf. tombetsense Matsumoto 4016
Gaudryceras hamanakense Matsumoto & Yoshida 2023, 4019
Gaudryceras makarovense sp. nov. 2023, 2025, 2029,
2031, 4030
Anagaudryceras seymouriense Macellari 4016
Anagaudryceras matsumotoi Morozumi 2021, 2022, 4014, 2029p
4015, 4016, 4018
Zelandites varuna (Forbes) 3031p
Tetragonites popetensis Yabe 2014 2021, 4014
Saghalinites teshioensis Matsumoto 2014
Pseudophyllites indra (Forbes) 4014, 4015, 4016, 2031
4018
Schlueterella kawadai Matsumoto & Miyauchi 2014
Diplomoceras cf. notabile Whiteaves 4030
Glyptoxoceras sp. 2036
Desmophyllites diphylloides (Forbes) 2014
Canadoceras kossmati Matsumoto 2014, 2015
Canadoceras multicostatum Matsumoto 2014, 4010
Menuites soyaensis (Matsumoto & Miyauchi) 2014, 2017
Pseudomenuites sp. 2014
Pachydiscus gracilis Matsumoto 4017, 4018
Pachydiscus flexuosus Matsumoto 2023 2029, 2031, 2036,
4025, 4028, 4029,
4030, 4032, 4033,
4035
Inoceramids
Sphenoceramus hetonaianus (Matsumoto) 2021, 3029, 4014,
4015, 4016, 4018
Shahmaticeramus shahmati (Salnikova & Zonova) 2021, 4016, 4018
4016, 4018
Shahmaticeramus kusiroensis (Nagao & Matsumoto) 4018
Crustacea
Linuparus sp. 4018 2030, 2036, 4035
as much larger burrows oriented obliquely to
the bedding plane. The sandy mudstone also
contains huge (50–100cm in diameter) spheri-
cal calcareous nodules, some of which are fos-
siliferous. A few vitric tuff beds varying in
thickness from 2 to 5cm are intercalated in the
upper part (Locs. MK2018, 2019).
Microfossils:Cyclagelosphaera sp. and
Watznaueria biporta Bukry occur in samples
018 and 017, respectively.
Megafossils:Canadoceras multicostatum
Matsumoto (Fig. 12) is the characteristic am-
monoid in the lower part of the K1 Unit, but
Tetragonites popetensis Yabe (Fig. 44), Menu-
ites soyaensis (Matsumoto and Miyauchi)
(Fig. 13), and Pseudomenuites sp. (Fig. 13) are
also common (Table 3). Relatively few fossils
were found in the upper part of the K1 Unit.
K2 Unit
Exposures:Locs. MK4012–4019 along
the middle course of the Victoria R. (typical
section); middle course of the Acacia R., and
Gruzdovka R.
Thickness: 200–500m.
Stratigraphic relationship:The K2 Unit
conformably overlies the K1 Unit, and con-
formably underlies the K3 Unit.
Lithology:The lower part of the K2 Unit
consists of gray to light greenish gray, cross-
stratified, coarse to medium grained sandstone.
Most of the cross-stratification can be classi-
fied as trough-type displaying a gentle angle,
while a few beds exhibit features that are char-
acteristic of hummocky cross-stratification
(HCS). Occasionally, the top-most beds of
these structures show current ripples suggest-
ing a north to south paleocurrent (Loc.
MK4013). A key, widely traceable 30cm
thick, yellowish gray, vitric tuff bed occurs in
the basal part of the unit (Loc. MK4013).
The upper part of the K2 Unit becomes fine
grained and is mainly comprised of dark gray,
intensely bioturbated coarse mudstone, con-
taining ellipsoidal calcareous concretions
20–40cm in diameter.
Microfossils:No nannofossils were found
in the K2 Unit.
Megafossils:The basal sandstone yields
no fossils, but the overlying sandy mudstone is
quite fossiliferous (Table 3). Gaudryceras
tombetsense Matsumoto (Figs. 26–31) is the
characteristic ammonoid in the lower part of
the unit, but Pseudophyllites indra (Forbes)
(Figs. 46–50) and Anagaudryceras matsumotoi
Morozumi (Fig. 39) are also common in the
lower and middle parts. Sphenoceramus heton-
aianus (Matsumoto) (Fig. 18) is frequently
found in the lower and middle parts. A form of
Pachydiscus gracilis Matsumoto (Fig. 14) that
is much more compressed than the holotype,
frequently occurs in the middle part of the
unit. A lobster (Linuparus sp., Fig. 10) and
Cidaris sp. are also common in the middle
part. Gaudryceras hamanakense Matsumoto
and Yoshida (Fig. 32) is found in the upper
part. A specimen of Zelandites varuna
(Forbes) (Fig. 38) was obtained from a float
calcareous nodule at Loc. MK3031 along the
Gruzovka River. Although the exact horizon
from which the nodule came is uncertain,
judging from the locality and lithology, it al-
most without doubt came from the upper part
o the unit.
K3 Unit
Exposures:Locs. MK2023–2040 along the
middle course of the Acacia R. (typical sec-
tion); middle course of the Victoria R., and
Gruzdovka R.
Thickness: 400–500m.
Stratigraphic relationship:The K3 Unit
conformably overlies the K2 Unit, and con-
formably underlies the K4a Subunit.
Lithology:The lower part of the K3 Unit
consists of gray, coarse to medium grained,
bedded sandstone varying in thickness from
50 to 250cm. Relatively few mudstone inter-
calations are present in this sandstone. Alter-
nating beds of sandstone and sandy mudstone
comprise the middle part of the unit. The
sandstone beds sometimes show parallel lami-
38 Haruyoshi Maeda et al.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 39
Fig. 9. 1, A distant view of Loc. MK2014 along the Acacia River. The exposure is the Upper Campanian bedded
muddy sandstone of the K1 Unit, Krasnoyarka Formation. 2, A view of Loc. MK2036 along the Acacia River.
Maastrichtian muddy sandstone of the K3 Unit yields many calcareous nodules. The second author (Y.S.) is
shown trying to excavate one of the nodules. 3, A calcareous nodule, found in the river at Loc. MK 2025, con-
taining a 15 cm in diameter specimen of Pachydiscus flexuosus Matsumoto. Specimen deposited in DGMKU.
40 Haruyoshi Maeda et al.
Fig. 10. A large calcareous nodule containing Linuparus sp. from the K2 Unit at Loc. MK4018. Note that the an-
tennae and appendages are preserved in situ even though the carapace is crushed. Specimen deposited in
DGMKU. Scale bar5cm.
nations. In the upper part of the unit, dark
greenish gray, intensely bioturbated sandstone
is dominant. Spherical calcareous nodules are
common in the sandy mudstone (Fig. 9).
In addition, a key, widely traceable, 90 to
120cm thick, yellowish gray, fine grained,
vitric tuff bed, displaying parallel laminations,
is intercalated in the sandy mudstone (Loc.
MK2027).
Microfossils:No nannofossils were found
in the K3 Unit.
Megafossils:Pachydiscus flexuosus Matsu-
moto (Fig. 15) and Gaudryceras makarovense
Shigeta and Maeda sp. nov. (Figs. 15, 33–37)
are abundant in the middle part of the K3
Unit. An identical assemblage is typically
found in the Pugachevo area (see Maeda &
Shigeta, 2005; another article in this volume).
P. flexuosus, Glyptoxoceras sp. (Fig. 51),
Nanonavis sp. and Linuparus sp. occur spo-
radically in the upper part of the unit.
K4 Unit
The sedimentological features of the K4
Unit, which is the uppermost lithostratigraphic
unit of the Krasnoyarka Formation, are some-
what different from those of the three underly-
ing units. Unlike the lower units of the forma-
tion, the K4 Unit exhibits a coarsening-upward
sequence, which resembles a deltaic sequence
(Walker & James, 1992). The K4 Unit is sub-
divided into two distinct subunits, K4a and
K4b, which are described separately.
K4a Subunit
Exposures:Locs. MK2041–2049 along the
upper course of the Acacia R. (typical sec-
tion); upper course of the Victoria R.
Thickness: 200–500m.
Stratigraphic relationship:The K4a Sub-
unit conformably overlies the K3 Unit, and
conformably underlies the K4b Subunit.
Lithology:The K4a Subunit consists
mainly of gray to light gray, cross-stratified,
medium to fine grained sandstone. For the
Yezo Group, the sandstone is exceptionally
well-sorted, thus indicating probable deposi-
tion under relatively strong wave action and/
or currents. Low-angle cross-stratified, fine
grained sandstones, whose margins converge
on the surrounding beds, are dominant in the
lower part (Loc. MK2044). The distinctive
features of these beds suggest that they can be
classified as hummocky cross-stratified sand-
stone (HCS) formed by storm events. In the
upper part of the unit, medium-grained sand-
stones displaying trough-type cross-stratifica-
tion are dominant (Loc. MK2048).
In the section along the Victoria River, the
lithology is highly variable, and many different
sediment types are intercalated in the K4a
Subunit. These include dark gray sandy mud-
stone (Loc. MK4040), a pebble conglomerate
bed 10–30cm thick (Loc. MK4045 etc.), a
medium-grained sandstone displaying tabu-
lar cross-stratification (Loc. MK4046), coal
seams 5–12cm thick (Loc. MK4048), and
andesitic volcanic breccia 10m thick (Loc.
MK4042).
Microfossils:No nannofossils were found
in the K4a Subunit.
Megafossils:No fossils were found in the
cross-stratified sandstones. Only rare speci-
mens of Nanonavis sp. were found in the
sandy mudstone in the Victoria section.
K4b Subunit
Exposures:Locs. MK2050–2061 along
the upper course of the Acacia River (typical
section).
Thickness:Greater than 450m.
Stratigraphic relationship:The K4b Sub-
unit conformably overlies the K4a Subunit.
The top portion is in fault contact with the
Bykov Formation, which is again exposed
along the axis of an anticline in the western
part of the area.
Lithology:The unit consists mainly of
poorly sorted, mottled, sandy mudstone inter-
calated in thin sandstone beds and beds of vit-
ric tuff.
Microfossils:No nannofossils were found
Stratigraphy of the Upper Cretaceous System in the Makarov Area 41
in the K4b Subunit.
Megafossils:No fossils were found except
allochthonous shell fragments of bivalves
which have accumulated as debris in the sand-
stone along with pebbles and patches of shale.
Correlation
We propose a provisional stratigraphic cor-
relation of the Cretaceous deposits in the
Makarov area based on the biostratigraphy of
ammonoids, inoceramids and calcareous nan-
nofossils. Then, once all currently ongoing in-
vestigations have been completed, the results
as well as a comprehensive discussion of our
conclusions will be published elsewhere. In-
vestigations still in progress include mag-
netostratigraphy, and oxygen and carbon iso-
tope stratigraphy.
The Cretaceous deposits in the Makarov
area are similar lithologically to those of the
stratotype section in the Naiba area. More
specifically, the Bykov Formation is equivalent
to the Upper Yezo Group, while the Krasno-
yarka Formation can be correlated with the
Hakobuchi Group in Hokkaido, Japan (Matsu-
moto, 1942d, 1954; Shigeta et al., 1999; Ko-
dama et al., 2002).
Based on ammonoid assemblages (Matsu-
moto, 1942d, 1954, 1959a; Poyarkova, 1987;
Zonova et al., 1993; Toshimitsu et al., 1995
etc.), the B1 Unit of the Bykov Formation is
supposed to be of Coniacian or Santonian
age, whereas the occurrence of Gaudryceras
tenuiliratum Yabe in the lower and middle part
of the B3 Unit indicates that these sediments
are of Santonian age.
A change in the fossil assemblage in the
upper part of the B3 Unit, in which Menuites
naumanni and Sphenoceramus orientalis are
common, suggests that this portion of the unit
is correlated to the uppermost Santonian or
lowermost Campanian stage (Matsumoto,
1959a; Kanie, 1966). The overlying B4 Unit
yields Sphenoceramus schmidti, the index fos-
sil of the widely traceable, 100m thick S.
schmidti Zone, which is the Lower Campanian
stage.
Based on the occurrence of nannofossil
species Reinhardtites anthophorus, R. levis
and Arkhangelskiella cymbiformis, the B4 Unit
ranges from the Lower to Upper Campanian
stage, which is equivalent to nannofossil zones
NC17–20 of Roth (1978), CC17–22 of Siss-
ingh (1977, 1978) and UC13–15 of Burnett
(1998). Both A. cymbiformis and R. levis have
their FOs in the Lower Campanian (UC13 and
UC14, respectively), while R. anthophorus has
its LO in the Upper Campanian (upper bound-
ary marker for UC15). According to Burnett
(1998), the Campanian–Santonian boundary
occurs slightly below the FO of A. cymbi-
formis (lower boundary marker for UC13).
Therefore, the occurrence of A. cymbiformis in
the lower part of the B4 Unit suggests that the
Campanian–Santonian boundary should lie
within the basal part of the B4 Unit or the
upper part of the B3 Unit.
The overlying K1 Unit of the Krasnoyarka
Formation is the Upper Campanian stage as
indicated by the presence of Canadoceras
multicostatum and associated fauna, e.g., Me-
nuites soyaensis. This assemblage is also
known as the “Soya Fauna” (see Matsumoto &
Miyauchi, 1984). Although one of the diag-
nostic species, Metaplacenticeras subtilistria-
tum (Jimbo), has not yet been reported from
Sakhalin, the “Soya Fauna” is widely traceable
throughout Hokkaido and southern Sakhalin
(Shigeta et al., 1999; Kodama et al., 2002).
Lower Maastrichtian faunas first appear in
the K2 Unit. Among these, Sphenoceramus
hetonaianus, Gaudryceras tombetsense, and
Pachydiscus gracilis are also known from the
Hakobuchi Group of Hokkaido (Matsumoto
1984b; Matsumoto et al., 1979, 1985; Toshim-
itsu et al., 1995). The K3 Unit frequently
yields Pachydiscus flexuosus and Gaudryceras
makarovense sp. nov., an assemblage that typi-
cally can be found in the Pugachevo area,
about 50km south of the Makarov area (see
another paper in this volume). P. flexuosus is
42 Haruyoshi Maeda et al.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 43
Fig. 11. Menuites naumanni (Yokoyama) from the B3 Unit, Bykov Formation, along the upper course of the Vic-
toria River. 1–2, NSM PM17268. 3, NSM PM17269. 4, NSM PM17270. Different views of the same speci-
men are linked by the white line (same as in Figs. 12, 13, and 15). Scale bar5cm.
44 Haruyoshi Maeda et al.
Fig. 12. 1–2, Canadoceras kossmati Matsumoto, NSM PM17271, from the uppermost part of the B4 Unit at
Loc. MK4008. 3–4, Canadoceras multicostatum Matsumoto, NSM PM17272, from the basal part of the K1
Unit at Loc. MK2014. Scale bar5cm.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 45
Fig. 13. 1–2, Menuites soyaensis (Matsumoto and Miyauchi), NSM PM17273, from the basal part of the K1 Unit
at Loc. MK2014. 3–5, “Pseudomenuites” sp. from the same locality as Menuites soyaensis. 3, NSM
PM17274. 4–5, NSM PM17275. Scale bar5cm.
46 Haruyoshi Maeda et al.
Fig. 14. Comparison of three Maastrichtian species of Pachydiscus from Sakhalin. 1, 4, Pachydiscus gracilis
Matsumoto, NSM PM17276, from the K2 Unit at Loc. MK4017. 2, 5, Strongly ribbed morphotype of Pachy-
discus flexuosus Matsumoto, NSM PM17277, from the Krasnoyarka Formation at Loc. PC1002 along the Pu-
gachevka River, Pugachevo area (Maeda & Shigeta, 2005). 3, 6, Pachydiscus subcompressus Matsumoto,
DGMKU specimen, from the Krasnoyarka Formation at Loc. NB7024 along the Seim River, Naiba area (this
specimen is figured in Kodama et al., 2002, p. 378, fig. 8H). Note that P. subcompressus has a compressed dis-
coidal shell whose sides are flat and parallel, and fine costae which are independent of the umbilical bullae. P.
flexuosus shows a wide morphological variation. The strongly ribbed morphotype in the middle growth stage
(2, 5) could be mistakenly identified as Canadoceras. Scale bar5cm.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 47
Fig. 15. Upper Maastrichtian ammonoids from the K3 Unit along the Victoria River. 1, 2, 4, 5, Pachydiscus flex-
uosus Matsumoto. 1, NSM PM17278, from Loc. MK4029. 2, DGMKU specimen, from Loc. MK4028. 4–5,
NSM PM17279, from Loc. MK4030. 3, Gaudryceras makarovense Shigeta and Maeda, sp. nov., NSM
PM17206, paratype, from Loc. MK4030. Each scale bar5cm. Upper scale bar—1, 2, 4 and 5; lower scale
bar—3.
normally indicative of the lower Upper Maas-
trichtian stage (Matsumoto et al., 1979;
Toshimitsu et al., 1995), but its stratigraphic
range is apparently much greater than we for-
merly anticipated.
The geological age of the K4a and K4b sub-
units remains uncertain because no direct, age
diagnostic evidence has been found. The Sine-
gorsk Fauna, which would apparently suggest
a Danian age (Kalishevich & Posylny, 1958;
Kalishevich et al., 1981; Poyarkova, 1987),
was not found during this study.
Among the calcareous nannofossils found
in the B3 and B4 units, Repagulum parviden-
tatum is the most common. The occurrence of
this normally high latitude index species sug-
gests that the B3 and B4 units were deposited
during Campanian time under the influence of
cold water conditions (Crux, 1991).
Discussion
The significance of the Cretaceous section
in the Makarov area (Makarov section) can be
summarized as follows.
1) A fossiliferous section in the northern
part of southern Sakhalin, ranging in age from
Santonian to Maastrichtian has been discov-
ered.
2) A complete succession of the Spheno-
ceramus schmidti Zone, which is rarely found
in other areas, is documented.
3) The mode of occurrence of a character-
istic Maastrichtian fossil assemblage repre-
sented by Pachydiscus flexuosus is document-
ed.
The Position of the Makarov section in the
“Yezo Basin”
The sedimentary features of the Cretaceous
Yezo Group (Supergroup) are similar
throughout southern Sakhalin and the eastern
central zone of Hokkaido: e.g., Wakkanai
(Matsumoto & Miyauchi, 1984), Nakaton-
betsu (Matsumoto et al., 1980; Ando et al.,
2001), Hidaka (Obata et al., 1973; Kawaguchi
& Kanie, 1985) and Urakawa areas (Kanie,
1966). Monotonous mudstone facies, indica-
tive of a deep offshore environment, predomi-
nate throughout the main part of the group.
Then, the mudstone facies gradually give way
to a shallowing-upward sequence in both
Sakhalin and Hokkaido. Such remarkable sed-
imentary continuity and uniformity are charac-
teristic of the deposits in the extensive “Yezo
Basin” (see Shigeta & Maeda, 2005 in this
volume).
Although slight differences exist at certain
localities, a regressive deltaic facies finally ap-
pears in the uppermost part of the group (ap-
prox. the Lower Campanian stage) at many
places in Hokkaido (Matsumoto, 1954;
Maeda, 1986; Takahashi et al., 2003 etc.).
Sedimentation becomes intermittent because
of erosion by strong wave and current action,
and certain fossil zones of the Cam-
panian–Maastrichtian stage are not recorded
there.
In contrast, the typical deltaic facies con-
sisting of a series of coarsening-upward se-
quences does not appear in the Krasnoyarka
Formation except in the uppermost part in
southern Sakhalin. In this area, marine sedi-
mentation appears to be continuous even in the
regressive phase of Campanian–Maastrichtian
age. This facies may be the result of deposi-
tion under a much deeper and quieter environ-
ment than that in Hokkaido. Therefore, strati-
graphic and faunal successions are exception-
ally well preserved in southern Sakhalin (Mat-
sumoto, 1942d, 1954; Poyarkova, 1987; Shige-
ta et al., 1999; Kodama et al., 2002).
The lithology of the Cretaceous strata in the
Makarov area is similar in detail to that of the
type section in the Naiba area (Poyarkova,
1987; Kodama et al., 2002). For example, in
the Naiba section the lithological transition
from the Bykov Formation to the overlying
Krasnoyarka Formation is identical to that in
the Makarov section located 200km to the
north. The succession consists of, in ascending
order: 1) massive mudstone, 2) greenish gray,
48 Haruyoshi Maeda et al.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 49
Fig. 16. 1, Sphenoceramus nagaoi (Matsumoto and Ueda), NSM PM17280, from the B3 Unit at Loc. MK2008,
1.0. 2, Anisomyon cassidarius (Yokoyama), NSM PM17281, from the B3 Unit at Loc. MK2008, 1.0. 3,
Gigantocaplustransformis (Dundo), NSM PM17282, from the uppermost part of the B3 Unit at Loc.
MK2062, 1.0. 4–5, Sphenoceramus orientalis (Sokolov), from the uppermost part of the B3 Unit at Loc.
MK2062. 4, NSM PM17283, 1.0. 5, NSM PM17284, 1.0.
50 Haruyoshi Maeda et al.
Fig. 17. 1, 2, 4, Sphenoceramus schmidti (Michael), from the B4 Unit at Loc. MK2009. 1, NSM PM17285, from
the upper part of the S. schmidti Zone, 0.4. 2, NSM PM17286, from the upper part of the S. schmidti Zone,
0.4. 4, NSM PM17288, from the basal part of the S. schmidti Zone, 0.4. 3, Gigantocaplus giganteus
(Schmidt), NSM PM17287, from the basal part of the B4 Unit (basal part of the S. schmidti Zone ) at Loc.
MK2009, 0.4.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 51
Fig. 18. 1–3, Sphenoceramus schmidti (Michael), from the basal part of the B4 Unit at Loc. MK2009. 1, NSM
PM17289, 1.0. 2, NSM PM17290, 1.0. 3, NSM PM17291, 1.0. 4–6, Sphenoceramus hetonaianus (Ma-
tsumoto), from the K2 Unit at Loc. MK2021. 4, NSM PM17292, 1.0. 5, NSM PM17293, 1.0. 6, NSM
PM17294, 1.0. 7–12, Shahmaticeramus shahmati (Salnikova and Zonova) from the K2 Unit. 7, NSM
PM17295 from Loc. MK2021, 1.0. 8, NSM PM17296 from Loc. MK2021, 1.0. 9. NSM PM17297 from
Loc. MK4016, 1.0. 10. NSM PM17298 from Loc. MK4018, 1.0. 11. NSM PM17299 from Loc. MK4018,
1.0. 12. NSM PM17300 from Loc. MK4018, 1.0. 13, 14, Shahmaticeramus kusiroensis (Nagao and
Matsumoto) from the K2 Unit at Loc. MK4018. 13, NSM PM17301, 1.0. 14, NSM PM17302, 1.0.
mottled muddy sandstone containing many
calcareous nodules, 3) dark greenish-gray,
poorly sorted, bedded coarse sandstone com-
posed of andesitic volcaniclasts, and 4) alter-
nating beds of greenish gray sandstone and
sandy mudstone in an upward sequence. One
of the remarkable characteristics of the Yezo
Group is its uniformity and continuity of litho-
facies and biofacies, extending over a distance
of 200km or more along an active plate mar-
gin.
However, in spite of the lithological similar-
ity of the Cretaceous System throughout
southern Sakhalin, it is obvious that the datum
planes of a few fossil zones extend across
some lithostratigraphic boundaries. For exam-
ple, in the Naiba section, the Lower Campan-
ian Sphenoceramus schmidti Zone is interca-
lated in the basal part of the Krasnoyarka For-
mation (Matsumoto, 1942d; Zakharov et al.,
1984; Poyarkova, 1987; Kodama et al., 2002).
On the other hand, in the Makarov section, the
S. schmidti Zone exists within the sandy mud-
stone of the B4 Unit of the Bykov Formation.
More specifically, in the Makarov area, the
FAD of S. schmidti is about 150 m below the
base of the Krasnoyarka Formation (Figs. 5,
6). These features aptly demonstrate the im-
portant problems inherent with chronological
correlation between lithofacies and biofacies.
A Complete succession of the Sphenocera-
mus schmidti Zone
Sphenoceramus schmidti is a well known
and a long established fossil taxon within the
Yezo Group. It usually occurs in traceable
shellbeds which represent the S. schmidti
Zone. Many workers have been interested in
the various aspects of this species because of
its abundant occurrence and peculiar morphol-
ogy of divergent ribs, e.g., biostratigraphy
(Pergament, 1974), taxonomy (Zonova, 1987;
Zonova et al., 1993; Tashiro et al., 1995), and
paleoecology (Hayami & Kanie, 1980; Tashiro
et al., 1995).
However, the S. schmidti Zone is incomplete
in nearly all sections in Hokkaido and south-
ern Sakhalin because of an increasing influx of
sands during the regressive phase (discussed
above). The FAD of S. schmidti, or the basal
part of the S. schmidti Zone, is observable in
various sections. However, the LAD of S.
schmidti, or upper part of the S. schmidti Zone,
is rarely preserved. The top part is not clearly
recognizable, even in the Naiba section. Our
studies reveal that in most cases, the so-called
S. schmidti Zone” discussed in various litera-
ture, actually represents only the basal part of
the zone.
In contrast, the Makarov section is a rare ex-
ample in which a complete, 100m thick, suc-
cession of the S. schmidti Zone is preserved
(Figs. 5, 6, 19). In the basal part of the S.
schmidti Zone, the morphotype possessing di-
agnostic divergent ribs in the adult stage is
abundant. At this level, Gigantocapulus gigan-
teus is closely associated with this particular
morphotype (Fig. 17; Locs. MK3003, 4005).
This association of S. schmidti and G. gigan-
teus has led us to, hypothesize that the two
species lived in a symbiotic relationship, with
the latter species attached to the shell-surface
of the former (Hayami & Kanie, 1980). This
hypothesis still appears to be valid, and our
observations reveal the following two points,
which will be utilized to test the principle in
further studies.
1) G. giganteus only occurs in the basal
part of the zone in association with the mor-
photype possessing divergent ribbing. G. gi-
ganteus completely disappears above the basal
part of the S. schmidti Zone (Fig. 19).
2) Without exception, G. giganteus attach-
es itself to the lower valve of S. schmidti, and
is always in the upside down position.
In the upper part of the S. schmidti Zone,
smooth morphotypes, in which the divergent
ribs appear only in the early growth stage, be-
come dominant (Figs. 17, 19; discussed later).
Several morphotypes, including the smooth
type, were needlessly divided into several
species by some authors (Pergament, 1974;
52 Haruyoshi Maeda et al.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 53
Fig. 19. Columnar section showing detailed occurrences of key species of the Sphenoceramus schmidti Zone in
the B4 Unit of the Bykov Formation along the Victoria River. A complete succession of the S. schmidti Zone
is well observable. Solid circle: occurrence of morphotype possessing divergent ribs in adult shells; open cir-
cle: morphotype possessing smooth adult shells. Note that Gigantocapulus giganteus (solid triangle) is associ-
ated only with the former morphotype, and occurs restrictedly from the basal part of the S. schmidti Zone.
Zonova, 1987; Zonova et al., 1993). However,
it is now known that S. schmidti exhibits
a very wide range of morphological varia-
tion. The successive change of morphotypes
shown in Fig. 19 can also be explained by
heterochrony within a single evolutional
biospecies, i.e., the timing of the appearance
of divergent ribs has been ontogenetically ac-
celerated. Therefore, we herein include all of
the morphotypes within the synonymy of S.
schmidti.
The discovery of a complete succession of
the S. schmidti Zone in the Makarov area is
very important for further research. Further-
more, Japanese workers must be mindful that a
complete succession of the S. schmidti Zone
does not exist on Hokkaido. For this reason,
we attach even greater importance to the
Makarov section. Failure to recognize that the
S. schmidti Zone in Hokkaido consists of only
partial successions, will merely lead to false
assumptions and conclusions about the zone.
Aspects of the Maastrichtian faunas
The Maastrichtian assemblages in the
Makarov area, which consist of Pachydiscus,
Gaudryceras, Linuparus, and Cidaris, resem-
ble those in the Pugachevo, Manui, and
Kril’on areas in southern Sakhalin (Zonova et
al., 1993; Yazikova, 1994; Shigeta et al., 1999)
and the Nakatonbetsu and Hobetsu areas in
Hokkaido (Matsumoto et al., 1979, 1980;
Ando et al., 2001). The faunal contents are
also similar to those of the Izumi Group in
southwest Japan (Matsumoto & Morozumi,
1980; Morozumi, 1985). Among the various
pachydiscid species, P. flexuosus (Fig. 15) fre-
quently occurs in the Makarov area. Our ob-
servations reveal that P. flexuosus is widely
distributed in Maastrichtian successions
throughout southern Sakhalin and Hokkaido.
P. flexuosus may be indigenous to the North
Pacific Realm, and it has several related
species.
In contrast, the well-known species Pachy-
discus subcompressus Matsumoto occurs in
the Krasnoyarka Formation in the Naiba and
Sinegorsk areas (Fig. 14; Matsumoto, 1942d,
1954; Kodama et al., 2002, table 3, fig. 8).
However, it is not found in the Makarov area,
even though several specimens mistakenly
identified as P. subcompressus have been listed
in various papers.
P. subcompressus is clearly distinguishable
morphologically from P. flexuosus and its re-
lated species. P. subcompressus has very com-
pressed whorls, whose flanks are nearly flat,
and shell ornamentation is clearly distin-
guished by umbilical bullae and short, sepa-
rate ventrolateral ribs (Fig. 14). These features
closely resemble those of the European type
species, P. neubergicus (Hauer) and the Indian
species: P. compressus Spath (Kossmat,
1895–1898).
In the Naiba section, P. subcompressus is
usually associated with Zelandites varuna, an-
other important element of the Indian Maas-
trichtian fauna (Kodama et al., 2002, fig. 8).
This volume of evidence suggests that P. sub-
compressus is not indigenous to the North Pa-
cific Realm, but is actually a “foreign species”,
which migrated northward from the Indian
province.
Systematic Paleontology
(By Y. Shigeta and H. Maeda)
Abbreviations:Dshell diameter; Uum-
bilical diameter; Hwhorl height; Bwhorl
width.
Suborder Phylloceratina Arkell, 1950
Superfamily Phylloceratoidea Zittel, 1884
Family Phylloceratidae Zittel, 1884
Genus Hypophylloceras Salfeld, 1924
Subgenus Neophylloceras Shimizu, 1934
Type species:Ammonites (Scaphites?) ramo-
sus
Meek, 1857.
Remarks:Neophylloceras was established
by Shimizu (1934, p. 61 in Shimizu and
54 Haruyoshi Maeda et al.
Obata), and has been regarded as either within
the synonymy of Hypophylloceras, as a sub-
genus of Hypophylloceras or Phylloceras, or
an independent genus. We herein follow
Wright et al. (1996) and treat Neophylloceras
as a subgenus of Hypophylloceras.
Hypophylloceras (Neophylloceras)
victriense sp. nov.
Figs. 20–23
Type:Holotype, NSM PM17171, is from
Loc. MK4018 along the Victoria River, and
consists mostly of the phragmocone of a large
shell.
Material (Paratypes): Three specimens,
NSM PM17172–17174, from Loc. MK4016,
and three specimens, NSM PM17175–17177,
from Loc. MK4018 along the Victoria River.
Diagnosis:Very involute, large-sized Neo-
phylloceras with compressed whorl section
and nearly smooth or very weak ribs on later
whorls. Suture is as for Neophylloceras.
Dimensions:See Table 4.
Description:Early whorls (up to 20mm in
diameter). Involute shell characterized by a
very narrow umbilicus with a very steep um-
bilical wall, and a compressed oval whorl sec-
tion with gently rounded flanks and rounded
venter, with the greatest width occurring at
mid-flank. Ornamentation consists of fine,
dense, lirae, which arise at the umbilical seam,
sweep gently forward across the inner flank,
and then pass straight across the mid-flank and
venter.
Middle and later whorls (over 20mm in di-
ameter). As size increases, the whorl section
becomes more compressed, with nearly paral-
lel flanks and rounded venter, with the greatest
width occurring at mid-flank. The umbilicus is
narrow with a very steep wall and abruptly
rounded shoulder. On later whorls the lirae
gradually become distant, barely raised ribs,
while the internal mold becomes almost
smooth. The suture is barely visible, but obvi-
ously consists of numerous deeply incised ele-
ments with phylloid terminals.
Comparison:Hypophylloceras (Neophyllo-
ceras)
victriense sp. nov. closely resembles
some Maastrichtian species of Hypophyllo-
ceras such as H. (N.) nera (Forbes, 1846, p.
106), H. (N.) surya (Forbes, 1846, p. 106) and
H. (N.) groelandicum (Birkelund, 1965, p. 23),
but it is distinguished from the latter by having
very weak lirae or a nearly smooth shell sur-
face at middle to later growth stages.
Etymology:This species is named for the
Victoria River, which is the type locality.
Occurrence:The described specimens were
collected from a bed in which Sphenoceramus
hetonaianus and Shahmaticeramus kushiroen-
sis occur, in the K2 Unit of the Krasnoyarka
Formation in the Makarov area, Sakhalin. This
level is upper Lower to lower Upper Maas-
trichtian.
Hypophylloceras (Neophylloceras)
cf. nera (Forbes, 1846)
Fig. 24.1–24.4
cf. Ammonites Nera Forbes, 1846, p. 106, pl. 8, fig. 7.
cf. Phylloceras nera (Forbes). Kossmat, 1895, p. 109, 160,
pl. 16, fig. 2.
cf. Phylloceras (Neophylloceras) nera (Forbes). Kennedy
and Henderson, 1992, p. 389, pl. 1, figs. 10–12, pl. 15,
figs. 1–2, text-fig. 3A; Matsumoto and Toshimitsu,
1996, p. 3, pls. 1–2.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 55
Tabe 4. Measurements (in mm) of Hypophylloceras victriense Shigeta and Maeda sp. nov. at the last preserved septum.
Specimen D U H B U/D B/H
NSM PM17171 147.7 8.4 83.8 36.0 0.06 0.43
NSM PM17176 93.0 6.5 52.4 23.8 0.07 0.45
NSM PM17175 74.1 4.6 43.1 19.7 0.06 0.46
NSM PM17173 50.0 3.3 29.2 15.0 0.07 0.51
56 Haruyoshi Maeda et al.
Fig. 20. Hypophylloceras (Neophylloceras) victriense Shigeta and Maeda, sp. nov. 1–4, NSM PM17171, holo-
type, from Loc. MK4018. Scale bar5cm.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 57
Fig. 21. Hypophylloceras (Neophylloceras) victriense Shigeta and Maeda, sp. nov. 1–2, NSM PM17172,
paratype, from Loc. MK4016, 1.0. 3–4, NSM PM17173, paratype, from Loc. MK4016, 1.0. 5–7, NSM
PM17174, paratype, from Loc. MK4016, 1.0. 8–10, NSM PM17175, paratype, from Loc. MK4018, 1.0.
58 Haruyoshi Maeda et al.
Fig. 22. Hypophylloceras (Neophylloceras) victriense Shigeta and Maeda, sp. nov. 1–4, NSM PM17176,
paratype, from Loc. MK4018, 1.0.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 59
Fig. 23. Hypophylloceras (Neophylloceras) victriense Shigeta and Maeda, sp. nov. 1–3, NSM PM17177, paratype, from Loc. MK4018, 0.7.
Material:Two specimens, NSM PM17178,
17179, from Loc. MK4016 along the Victoria
River.
Description:Very involute shell distin-
guished by a compressed oval whorl section
with nearly parallel flanks and rounded venter,
with the greatest width occurring at mid-flank.
The umbilicus is narrow with a very steep wall
and rounded shoulder. Ornamentation consists
of fine, dense lirae, which arise at the umbili-
cal seam, sweep gently forward across the
inner flank, and then pass straight across mid-
flanks to the venter. Flanks of inner whorls are
ornamented by broad undulations.
Although the suture is not completely ex-
posed on the present specimens, the visible
portions are deeply incised and finely divided.
Discussion:Hypophylloceras (Neophyllo-
ceras) nera was established for a small, appar-
ently immature specimen from the Maastricht-
ian of southern India. However, Matsumoto
and Toshimitsu (1996) provided a revised di-
agnosis for the species based on three larger
specimens and a smaller one collected from
the Sphenoceramus hetonaianus-Pachydiscus
gracilis Zone (upper Lower Maastrichtian) in
the Hobetsu area, central Hokkaido. Conse-
quently, the distinctive features of the present
specimens enable us to identify them with rea-
sonable confidence as H. (N.) nera.
Occurrence:The described specimens were
found in the same bed in which Sphenocera-
mus hetonaianus occurs in the K2 Unit of the
Krasnoyarka Formation in the Makarov area,
Sakhalin. This level is upper Lower to lower
Upper Maastrichtian.
Genus Phyllopachyceras Spath, 1925
Type species:Ammonites infundibulum
d’Orbigny 1841.
Phyllopachyceras ezoense (Yokoyama, 1890)
Fig. 24.5–24.11
Phylloceras ezoense Yokoyama, 1890, p. 178, pl. 19, fig.
2; Yabe and Shimizu, 1921, p. 54, pl. 8, fig. 2.
Phyllopachyceras ezoense (Yokoyama). Matsumoto,
1942c, p. 674; Matsumoto and Obata, 1955, pl. 30, fig.
3; Matsumoto and Miyauchi, 1984, p. 38, pl. 10, figs.
3–4; Alabushev and Wiedmann, 1997, p. 6, pl. 1, figs.
3–5.
Type:Repository of the holotype (Yokoya-
ma, 1890, p. 178, pl. 19, fig. 2), from the Yezo
Group in the Urakawa area, south central
Hokkaido, is the Bavarian State Collection of
Palaeontology and Geology in Munich, Ger-
many. Its exact collection locality and horizon
are unknown.
Material:Two specimens, NSM PM17180,
17181, from Loc. MK2062 along the Acacia
River. NSM PM17182, from Loc. MK2015
along the Acacia River.
Description:Very involute shell, charac-
terized by a very narrow, deep, funnel-shaped
umbilicus and a slightly inflated, sub-circular
whorl section with a moderately arched venter.
The greatest width occurs at mid-flank. Orna-
mentation consists of dense, very fine prorsira-
diate lirae that cross the flanks and then be-
come slightly sinuous on the ventrolateral
shoulders, before crossing the venter in a
broad convex arch. Mature whorls are orna-
mented by frequent, strong, rounded, prorsira-
diate ribs which originate low on the flank and
cross the venter in a moderately broad convex
arch. The suture line is not exposed.
Occurrence:The described specimens were
collected in the Sphenoceramus orientalis and
Canadoceras kossmati bearing beds in the B3
and B4 units of the Bykov Formation, in the
Makarov area, Sakhalin. These levels are
equivalent to the upper Lower Campanian, but
the species is abundant in beds of Turonian to
Campanian age in Hokkaido and Sakhalin
(Toshimitsu & Hirano, 2000).
60 Haruyoshi Maeda et al.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 61
Fig. 24. 1–4, Hypophylloceras (Neophylloceras) cf. nera (Forbes). 1–2, NSM PM17178, from Loc. MK4016,
1.0. 3–4, NSM PM17179, from Loc. MK4016, 1.0. 5–11, Phyllopachyceras ezoense (Yokoyama). 5–7,
NSM PM17180, from Loc. MK2062, 1.0. 8–9, NSM PM17182, from Loc. MK2015, 1.0. 10–11, NSM
PM17181, from Loc. MK2062, 1.0.
Suborder Lytoceratina Hyatt, 1889
Superfamily Tetragonitoidea Hyatt, 1990
Family Gaudryceratidae Spath, 1927
Genus Gaudryceras de Grossouvre, 1894
Type species:Ammonites mitis Hauer, 1866.
Gaudryceras striatum (Jimbo, 1894)
Fig. 25.1–25.3
Lytoceras striatum Jimbo, 1894, p. 181, pl. 22, fig. 6.
Gaudryceras striatum (Jimbo). Yabe, 1903, p. 31, pl. 4,
fig. 5; Haggart, 1989, p. 189, pl. 8.2, figs. 1–11.
Gaudryceras striatum (Jimbo) var. picta Yabe, 1903, p.
33, pl. 4, fig. 6.
Type:Holotype, UMUT. MM7493 (Jimbo,
1894, p. 181, pl. 22, fig. 6), is from the Yezo
Group in the Nakagawa area, northern
Hokkaido. Its exact collection locality and
horizon are unknown.
Material:NSM PM17183, from Loc.
MK2062 along the Acacia River.
Description:Very evolute shell, character-
ized by a rounded but slightly depressed whorl
section, with the greatest width occurring
slightly below mid-flank, and a wide, shallow
umbilicus with a rounded wall. The whorl
sides and venter are rounded. Ornamentation
consists of fine, dense lirae, which arise at the
umbilical seam and become quite sinuous, ap-
proaching a sigmoidal pattern, before culmi-
nating on the venter in a broad, convex arch.
Most of these lirae arise at, or just above the
umbilical seam but a few are intercalated on
the inner flanks. In addition to the lirae, nar-
row, rounded, variable close or distant, collar-
like ribs, parallel to the lirae, occur on all
whorls. The suture line, with large, incised,
bifid lobes and saddles, is typical of gaudry-
ceratids.
Remarks:Jimbo (1894, p. 181) provided a
diagnosis of the species based on a single
specimen 47mm in diameter, and then Yabe
(1903, p. 31) revised and supplemented the di-
agnosis with an additional specimen, 72mm in
diameter, from the type locality. The present
specimen exhibits no appreciable differences
from the holotype or from the inner whorl of
Yabe’s specimen, and it also closely matches
the specimens described as Gaudryceras stria-
tum by Haggart (1989) from British Columbia.
As Haggart (1989) noted, Yabe’s variety of
Gaudryceras striatum var. picta is nearly iden-
tical to G. striatum in most details of morphol-
ogy and ornamentation, and therefore, he in-
cluded it within Gaudryceras striatum.
G. striatum closely resembles G. tenuilira-
tum Yabe (1903, p. 19), which occurs in
Coniacian to lower Lower Campanian sedi-
ments of Hokkaido and Sakhalin, in size,
shape and general pattern of ornamentation,
but it is distinguished by its finer and denser
lirae. This species is also very similar to the
phragmocones of the Upper Campanian
species Gaudryceras crassicostatum (Jimbo,
1894, p. 182) and the three Maastrichtian
species Gaudryceras hamanakense Matsumo-
to and Yoshida (1979, p. 68), Gaudryceras
tombetsense Matsumoto (1984b, p. 2) and
Gaudryceras venustum Matsumoto (1984b, p.
5) from Hokkaido, in having not only fine
lirae, but the lirae on the younger species are
bifurcated and intercalated with finer and
denser lirae on the outer flank and venter.
Also, the lirae of the Maastrichtian species is
distinctly coarser in the area of the umbilical
shoulder than in G. striatum.
Occurrence:The described specimen was
found in a bed with Sphenoceramus orientalis
(upper Lower Campanian), just below the
Sphenoceramus schmidti bearing bed (upper
Lower Campanian) in the B3 Unit of the
Bykov Formation in the Makarov area,
Sakhalin. The exact horizon from which the
holotype of Gaudryceras striatum was collect-
ed is unknown, but the species is common in
the S. orientalis and S. schmidti bearing beds
in Hokkaido and Sakhalin (Matsumoto, 1995).
This species also occurs in the S. schmidti
bearing bed in British Columbia, Canada.
62 Haruyoshi Maeda et al.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 63
Fig. 25. 1–3, Gaudryceras striatum (Jimbo), NSM PM17183, from Loc. MK2062, 1.0. 4–6, Gaudryceras cf.
mamiyai Matsumoto and Miyauchi. 4, NSM PM17184, from Loc. MK2015, 1.0. 5–6, NSM PM17185, from
Loc. MK2015, 1.0. 7–10, Gaudryceras crassicostatum (Jimbo). 7–8, NSM PM17186, from Loc. MK2014,
1.0. 9–10, NSM PM17187, from Loc. MK2014, 1.0.
Gaudryceras mamiyai Matsumoto and
Miyauchi, 1984
Fig. 26.1, 26.2
Gaudryceras mamiyai Matsumoto and Miyauchi, 1984, p.
55, pl. 24, fig. 1.
Type:Holotype, GK. H5974 (Matsumoto
& Miyauch, 1984, p. 55, pl. 24, fig. 1), is from
the Upper Campanian beds around the fishing
harbor of Kiyohama-II in the Soya area, north-
ern Hokkaido.
Material:NSM PM17188, from Loc. MK-
2009
along the Acacia River. This specimen,
consisting of a somewhat crushed phragmo-
cone and a portion of the body chamber, is
107mm in diameter at the last preserved sep-
tum. If complete it would approach 160mm in
diameter.
Description:During the early growth
stage the shell is evolute with slowly expand-
ing whorls and a rounded, slightly depressed
whorl section, but as growth approaches matu-
rity it becomes moderately evolute with rapid-
ly expanding whorls and a somewhat com-
pressed whorl section. The umbilicus is of
medium size with a steep umbilical wall.
Ornamentation on the phragmocone con-
sists of fine, slightly distant, raised ribs, which
originate just above the umbilical seam and
become moderately sinuous, approaching a
sigmoidal pattern, before culminating on the
venter in a moderately broad, convex arch. A
few of these ribs branch and intercalate at a
point low on the umbilical shoulder. Body
chamber ornamentation also consists of sinu-
ous ribs that tend toward a sigmoidal form, but
they are more distinct and slightly more dis-
tant than those on the phragmocone. Most of
the ribs are sharply raised with a gently slop-
ing adoral face and an abrupt, very steep
adapical face, and quite frequently some of
them are of such size and intensity that they
have the appearance of major ribs.
The suture line is only partly exposed but
large, incised, bifid lobes and saddles typical
of gaudryceratids are visible.
Remarks:Gaudryceras mamiyai closely
resembles Gaudryceras denmanense White-
aves (1901, p. 32) from the Upper Campanian
of British Columbia and southeast Alaska in
having narrowly raised ribs, but it is distin-
guished from the latter by having more fre-
quent major ribs on the adult body chamber.
This species is also similar to Gaudryceras
tenuiliratum Yabe (1903, p. 19), of Coniacian
to Campanian age from Hokkaido and
Sakhalin, in shell shape and general configura-
tion of ornament, but it is clearly distinguished
from the latter by having coarser ribs.
Occurrence:The described specimen was
found in a bed associated with Spenoceramus
schmidti (upper Lower Campanian) in the B4
Unit of the Bykov Formation in the Makarov
area, Sakhalin, while the holotype of Gaudry-
ceras mamiyai was found in a calcareous nod-
ule of greenish, dark grey, sandy siltstone, in a
pile of dredged rocks immediately northeast of
the fishing harbor of Kiyohama-II in the Soya
area, northern Hokkaido. The exact horizon
from which the nodule came is uncertain, but
judging from its locality and lithology, the
holotype probably came from the bed in which
Schlueterella kawadai (Upper Campanian) oc-
curs. Shigeta et al. (1999) reported the occur-
rence of Gaudryceras cf. mamiyai from the S.
schmidti bearing bed along the Kura River in
the Kril’on Peninsula, southern Sakhalin.
Gaudryceras cf. mamiyai Matsumoto and
Miyauchi, 1984
Fig. 25.4–25.6
cf. Gaudryceras mamiyai Matsumoto and Miyauchi, 1984,
p. 55, pl. 24, fig. 1.
Material:Two specimens, NSM PM17184,
17185, from Loc. MK2015 along the Acacia
River. Both specimens are partly deformed.
Description:Evolute shell, with a some-
what depressed whorl section during early
growth stage but becoming slightly com-
pressed as diameter increases. The umbilicus
is broad and shallow, with a steep initial wall
64 Haruyoshi Maeda et al.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 65
Fig. 26. 1–2, Gaudryceras mamiyai Matsumoto and Miyauchi, NSM PM17188, from Loc. MK2009, 0.75. 3,
Gaudryceras tombetsense Matsumoto, NSM PM17196, from Loc. MK4015, 0.75.
and broadly rounded shoulder. Flanks are
slightly rounded and venter is broadly round-
ed. Ornamentation consists of fine, dense lirae,
which arise at the umbilical seam, become sin-
uous, approaching a sigmoidal pattern, and
sweep across the venter in a broad, convex
arch. A few lirae branch at or just above the
umbilical seam, while several intercalate on
the flank. The suture line is not exposed.
Discussion:Although the present speci-
mens are partly deformed, their distinctive fea-
tures enable us to identify them with reason-
able confidence as Gaudryceras mamiyai.
Occurrence:The present specimens were
collected from a bed in which Canadoceras
kossmati (upper Lower Campanian) occurs,
just below the Schlueterella kawadai bearing
bed (Upper Campanian) in the uppermost part
of the B4 Unit of the Bykov Formation in the
Makarov area, Sakhalin.
Gaudryceras crassicostatum (Jimbo, 1894)
Fig. 25.7–25.10
Lytoceras crassicostatum Jimbo, 1894, p. 182, pl. 22, fig.
7.
Gaudryceras crassicostatum (Jimbo). Yabe, 1903, p. 29,
pl. 4, fig. 4; Matsumoto, 1984b, p. 6, pl. 4, figs. 1–3, pl.
5, figs. 1–2; Matsumoto et. al., 1985, p. 20, pl. 1, figs.
1–3, pl. 2, figs. 1–4, pl. 3, figs. 7–10.
Type:Holotype, UMUT. MM7492 (Jimbo,
1894, p. 182, pl. 22, fig. 7), is from the Yezo
Group in the Soya area, northern Hokkaido. Its
exact collection locality and horizon are un-
known.
Material:Two specimens, NSM PM17186,
17187, from Loc. MK2014 along the Acacia
River. Both specimens are slightly crushed and
deformed.
Description:Evolute shell with slowly ex-
panding whorls and a slightly compressed, but
somewhat inflated whorl section. The umbili-
cus is broad and shallow with a steep wall and
a broadly rounded shoulder. Ornamentation
consists of very fine flexuous lirae, which arise
at the umbilical seam and sweep over the shell
in a near sigmoidal form and culminate on the
venter in a broad convex arch. In addition, the
ventrolateral shoulder and venter are covered
with extremely fine, dense lirae resulting from
multiple branching and intercalation of the
normal lirae. All whorls bear moderately
strong, variable close or distant, fold-like ribs
that parallel the lirae. The suture lines are not
preserved.
Remarks:The phragmocone of Gaudry-
ceras crassicostatum is very similar to G.
striatum (Jimbo, 1894, p. 181) from the upper
Lower Campanian of Hokkaido and Sakhalin
in having fine lirae and periodic ribs, but is
distinguished from the latter by having numer-
ous, much finer lirae on the venter.
Occurrence:The present specimens were
associated with Schlueterella kawadai (Upper
Campanian) in a bed in the lower part of the
K1 Unit of the Krasnoyarka Formation in the
Makarov area, Sakhalin. Gaudryceras crassi-
costatum has also been reported from the S.
kawadai bearing bed in the Naiba area, south-
ern Sakhalin, and the Soya area, northern
Hokkaido.
Gaudryceras tombetsense Matsumoto, 1984b
Figs. 26.3, 27–31
Gaudryceras tombetsense Matsumoto, 1984b, p. 2, pl. 1,
figs, 1–2, pl. 2, figs. 1–4; Shigeta et al., 1999, pl. 6, fig.
1.
Gaudryceras hamanakense Matsumoto and Yoshida.
Yazykova, 1992, p. 196, pl. 111, figs. 1–2; Yazikova,
1994, p. 292, pl. 3, figs. 2–3.
Gaudryceras denmanense Whiteaves. Yazykova, 1993, p.
153, pl. 88, fig. 2; Yazikova, 1994, p. 291, pl. 6, fig. 3.
Type:Holotype, GK. H5991 (Matsumoto,
1984b, p. 2, pl. 1, figs. 1–2), is from the Yezo
Group in the Nakatombetsu area, northern
Hokkaido.
Material:NSM PM17262, from Loc. MK-
2022 along the Acacia River. Seven speci-
mens, NSM PM17189–17195, from Loc. MK-
4014, and seven specimens, PM17196–
17202, from Loc. MK4015 along the Victoria
River.
66 Haruyoshi Maeda et al.
Description:Early whorls (up to 50mm).
Very evolute shell, characterized by a moder-
ately inflated whorl section with rounded sides
and venter, and a wide, shallow umbilicus with
a rounded wall. Ornamentation consists of
very fine, dense, slightly sinuous lirae, which
arise at the umbilical seam and pass over the
venter in a broad convex arch. Bifurcation and
intercalation of the lirae occurs on the umbili-
cal shoulder and lower flank. Each whorl has
variable close or distant, rounded, collar-like
or fold-like ribs, running parallel to the lirae,
and each rib is immediately followed by a
shallow constriction. The collar-like ribs and
constrictions are covered with very fine lirae.
Middle whorls (50–100mm in diameter).
As size increases, the whorl section tends to
become slightly compressed, and the umbilical
width becomes smaller. The lirae gradually de-
velop into slightly more distant, narrowly
raised ribs, which increase in strength as diam-
eter increases. These ribs follow the same pat-
tern as on the earlier whorls but they tend to
become more sinuous as diameter increases. A
few ribs bifurcate at or just above the umbili-
cal seam and a few intercalatory ribs arise on
the flanks. Shallow, periodic constrictions are
present, and each constriction is accompanied
by an adjacent, parallel collar-like or fold-like
rib.
Later whorls (over 100mm in diameter). As
the shell grows larger the whorl expansion rate
increases and the whorl section becomes more
compressed while the umbilical width be-
comes progressively smaller. As the shell ma-
tures the ribs generally become much coarser
and more distant, with alternating ribs varying
somewhat in intensity, and the collar-like ribs
become more frequent. The suture line with its
large, incised and bifid lobes and saddles is
typical of gaudryceratids.
Remarks:The morphology of Gaudry-
ceras tombetsense is now recognized as being
distinctly different during the early, middle
and later growth stages. Yazykova (1992) and
Yazikova (1994) assigned a small gaudrycer-
atid from the Maastrichtian of the Makarov
area to Gaudryceras hamanakense Matsumoto
and Yoshida (1979, p. 68), but this specimen is
identical to the juvenile shell of G. tombe-
tsense. Yazykova (1993) and Yazikova (1994)
also assigned a large gaudryceratid of Maas-
trichtian age from the Nerpichya area, eastern
Sakhalin, to Gaudryceras denmanense White-
aves (1901, p. 32), but this specimen closely
matches the adult shell of G. tombetsense.
Occurrence:The present specimens were
collected from a bed in which Sphenoceramus
hetonaianus occurs in the K2 Unit of the Kras-
noyarka Formation in the Makarov area,
Sakhalin. The holotype of Gaudryceras
tombetsense was obtained from the lower
course of the Kikusui-gawa River, a tributary
of the Tombetsu River, while the paratype was
collected from a float calcareous nodule in the
Heitaro-zawa River, a tributary of the Tombe-
tsu River. Both localities are in the
Nakatombetsu area, northern Hokkaido. Al-
though the exact horizon which yielded the
type specimens is uncertain, judging from
their respective localities and matrix lithology,
they probably came from the bed in which S.
hetonaianus (Ando et al., 2001) occurs. Shige-
ta et al. (1999) reported the occurrence of this
species from the S. hetonaianus bearing bed
along the Naycha River in the Kril’on Penin-
sula, southern Sakhalin. S. hetonaianus is di-
agnostic of the upper Lower to lower Upper
Maastrichtian.
Gaudryceras cf. tombetsense Matsumoto,
1984b
Fig. 40.1–40.3
cf. Gaudryceras tombetsense Matsumoto, 1984b, p. 2, pl.
1, figs. 1–2, pl. 2, figs. 1–4.
Material:NSM PM17251, from Loc. MK-
4016
along the Victoria River.
Description:Very evolute shell, character-
ized by a slightly depressed and rounded whorl
section, with the greatest width at mid-flank,
and a wide, shallow umbilicus with a broadly
Stratigraphy of the Upper Cretaceous System in the Makarov Area 67
68 Haruyoshi Maeda et al.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 69
Fig. 28. Gaudryceras tombetsense Matsumoto. 1–2, NSM PM17199, from Loc. MK4015, 1.0. 3–4, NSM
PM17200, from Loc. MK4015, 1.0.
Fig. 27. Gaudryceras tombetsense Matsumoto. 1–2, NSM PM17189, from Loc. MK4014, 1.0. 3, NSM
PM17190, from Loc. MK4014, 1.0. 4, NSM PM17197, from Loc. MK4015, 1.0. 5, NSM PM17198, from
Loc. MK4015, 1.0. 6, NSM PM17191, from Loc. MK4014, 1.0.
70 Haruyoshi Maeda et al.
Fig. 29. Gaudryceras tombetsense Matsumoto. 1–2, NSM PM17202, from Loc. MK4015, 0.85. 3, NSM
PM17201, from Loc. MK4015, 0.85.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 71
Fig. 30. Gaudryceras tombetsense Matsumoto. 1, NSM PM17192, from Loc. MK4014, 0.85. 2, NSM
PM17193, from Loc. MK4014, 0.85.
72 Haruyoshi Maeda et al.
Fig. 31. Gaudryceras tombetsense Matsumoto. 1, NSM PM17195, from Loc. MK4014, 0.5. 2, NSM PM17194, from Loc. MK4015, 0.5.
rounded wall. Ornamentation consists of very
fine, dense, moderately sinuous lirae, which
arise at the umbilical seam and approach a sig-
moidal pattern before passing over the venter
in a broad convex arch. Although they are in-
visible to the naked eye, extremely fine, dense
lirae resulting from multiple branching and in-
tercalation of the normal lirae, cover the flanks
and venter. In addition, periodic, narrow,
rounded collar-like ribs, parallel to the lirae,
occur on all whorls. The sutures are not fully
exposed.
Discussion:Even though the present spec-
imen is an immature shell, its distinctive orna-
mentation and shell shape enable us to identify
it with probable confidence as Gaudryceras
tombetsense.
Occurrence:The present specimen was
collected from a bed in which Sphenoceramus
hetonaianus (upper Lower to lower Upper
Maastrichtian.) occurs in the K2 Unit of the
Krasnoyarka Formation in the Makarov area,
Sakhalin. This horizon is just above the
Gaudryceras tombetsense bearing bed.
Gaudryceras hamanakense Matsumoto and
Yoshida, 1979
Fig. 32.1–32.3
Gaudryceras hamanakense Matsumoto and Yoshida, 1979,
p. 68, pl. 10, figs. 1–3, pl. 11, figs. 1–2, text-fig. 2.
Type:Holotype, GK. H5873 (Matsumoto
& Yoshida, 1979, p. 68, pl. 10, fig. 1), came
from the main part of the Akkeshi Formation
of the Nemuro Group in the Hamanaka area,
eastern Hokkaido.
Material:NSM PM17203, from Loc. MK-
4019 along the Victoria River. NSM PM17204,
from Loc. MK2023 along the Acacia River.
Description:Very evolute shell, with a
low expansion rate, wide, shallow umbilicus,
and a somewhat depressed whorl section in the
younger stage, but becoming slightly com-
pressed as diameter increases. Ornamentation
consists of fine, dense lirae, which arise at the
umbilical seam and sweep forward over the
umbilical wall and shoulder, but then become
slightly flexuous on the lower flank, before
passing straight across the upper flank and
venter. At about mid-flank they subdivide into
numerous, extremely fine, dense lirae that are
almost invisible to naked eye. In addition, pe-
riodic, narrow, rounded collar-like ribs parallel
to the lirae, occur on all whorls. The suture
line with its large, incised, bifid lobes and sad-
dles is typical of gaudryceratids.
Remarks:Two specimens, described as
Gaudryceras hamanakense by Yazikova (1994,
p. 292, pl. 3, figs. 2–3, pl. 6, figs. 2–3) from
the Makarova area, are referred by us to
Guadryceras tombetsense Matsumoto (1984b,
p. 2).
Occurrence:Gaudryceras hamanakense
has been reported from the Pachydiscus flexu-
osus bearing bed, of late Maastrichtian age, in
the Nakatombetsu area, northern Hokkaido
(Ando et al., 2001) and the Hamanaka area,
eastern Hokkaido. The present specimens
were collected from the P. flexuosus bearing
bed in the uppermost part of the K2 Unit of
the Krasnoyarka Formation in the Makarov
area, Sakhalin.
Gaudryceras makarovense sp. nov.
Figs. 15.3, 32.4, 33–37
Gaudryceras denmanense Whiteaves. Yazykova, 1992, p.
195, pl. 111, fig. 3; Yazykova, 1993, p. 153, pl. 102, fig.
2; Yazikova, 1994, p. 291, pl. 8, fig. 2.
Gaudryceras hamanakense Matsumoto and Yoshida.
Yazykova, 1992, p. 196, pl. 110, figs. 1–2; Yazykova,
1993, p. 154, pl. 88, fig. 1, pl. 99, fig. 2, pl. 104, fig. 2;
Yazikova, 1994, p. 292, pl. 4, figs. 1–3.
Gaudryceras venustum Matsumoto. Yazykova, 1993, p.
152, pl. 87, fig. 1, pl. 102, fig. 1, pl. 103, fig. 3, pl. 104,
fig. 1; Yazikova, 1994, p. 292, pl. 14, pl. 5, fig. 2.
Gaudryceras izumiense Matsumoto and Morozumi. Mo-
rozumi, 1985, p. 24, pl. 8, fig. 2.
Type:Holotype, NSM PM17205, is from
Loc. MK4030 along the Victoria River.
Material (Paratypes): NSM PM17206,
from Loc. MK4030 along the Victoria River.
NSM PM17207, from Loc. MK2023, two
specimens, NSM PM17208, 17209, from Loc.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 73
74 Haruyoshi Maeda et al.
Fig. 32. 1–3, Gaudryceras hamanakense Matsumoto and Yoshida. 1–2, NSM PM17203, from Loc. MK4019,
1.0. 3, NSM PM17204, from the mudstone of the uppermost part of the K2 Unit of the Krasnoyarka Forma-
tion at Loc. MK2023, 1.0. 4–5, Gaudryceras makarovense Shigeta and Maeda, sp. nov., NSM PM17207,
paratype, from the sandstone of the lowest part of the K3 Unit of the Krasnoyarka Formation at Loc. MK2023,
1.0.
MK2025, three specimens, NSM PM17210–
17212, from Loc. MK2029, and four speci-
mens, NSM PM17213–17216, from Loc.
MK2031 along the Acacia River.
Diagnosis:Large-sized Gaudryceras with
fine lirae on early whorls, narrowly raised ribs
with gently sloping adoral face and nearly ver-
tical adapical face on middle whorls, and
dense ribbing with frequent collar-like ribs
that are adjacent to constrictions, on later
whorls.
Dimensions:See Table 5.
Description:Early whorls (up to 50mm).
Very evolute shell, with slowly expanding
whorls, a slightly depressed whorl section,
rounded whorl sides and venter, and a wide,
shallow umbilicus with an abruptly rounded
shoulder. Ornamentation consists of fine,
dense lirae, which arise at the umbilical seam
and become flexuous, approaching a sigmoidal
pattern, before crossing over the venter in a
broad, convex arch. The ventrolateral shoul-
ders and venter are also covered with extreme-
ly fine, dense lirae resulting from multiple
branching and intercalation of the regular
lirae. In addition, periodic, strengthened, fold-
like ribs, parallel to the lirae, occur on all
whorls.
Middle whorls (50–100mm in diameter).
As the shell grows, the whorl expansion rate
increases, the whorl section become progres-
sively less depressed, and the umbilicus be-
comes smaller in width and somewhat deeper.
Lirae become narrowly raised ribs, which in-
crease in strength with increasing diameter,
and they are distinguished by a gently sloping
adoral face and nearly vertical adapical face.
These ribs follow the same flexuous, near sig-
moidal pattern as those on the earlier whorls,
and they culminate on the venter in a broad,
convex arch. A few of the ribs branch and in-
tercalate at the umbilicus. Periodic constric-
tions, parallel to the lirae, are present but are
occasionally invisible to the naked eye.
Later whorls (over 100mm in diameter). As
the shell matures, the whorl expansion rate
continues to increase and the whorl cross sec-
tion becomes slightly more compressed, re-
sulting in an umbilicus that becomes progres-
sively deeper and smaller in width. Ribs be-
come denser, and collar-like ribs become fre-
quent.
The suture line, with large, incised, bifid
lobes and saddles, is typical of gaudryceratids.
Comparison:Gaudryceras makarovense sp.
nov. closely resembles Gaudryceras denma-
nense Whiteaves (1901, p. 32) from the Upper
Campanian of British Columbia and southeast
Alaska, and Gaudryceras mamiyai Matsumoto
and Miyauchi (1984, p. 55) from the Campan-
ian of Hokkaido and Sakhalin, in having nar-
rowly raised ribs with a gently sloping adoral
face and nearly vertical adapical face on the
middle whorls. It is distinguished from the lat-
ter by having denser ribs and more frequent
collar-like ribs on the adult body chamber.
Yazykova (1992, 1993) and Yazikova (1994)
described several gaudryceratids from the
Maastrichtian of the Makarov and Pugachevo
areas, and assigned them to Gaudryceras
venustum Matsumoto (1984b, p. 5), Gaudry-
ceras hamanakense Matsumoro and Yoshida
(1979, p. 68) or G. denmanense Whiteaves
(1901, p. 32), but these specimens are identi-
cal to G. makarovense sp. nov., with respect to
whorl section, mode of coiling, and ornamen-
tation.
Etymology:This species is named for
Stratigraphy of the Upper Cretaceous System in the Makarov Area 75
Tabe 5. Measurements (in mm) of Gaudryceras makarovense Shigeta and Maeda sp. nov. at the last preserved septum.
Specimen D U H B U/D B/H
NSM PM17205 108.0 38.2 46.0 36.0 0.35 0.78
NSM PM17213 39.0 17.0 13.8 14.4 0.44 1.04
NSM PM17215 35.4 17.7 10.3 12.0 0.50 1.17
76 Haruyoshi Maeda et al.
Fig. 33. Gaudryceras makarovense Shigeta and Maeda, sp. nov., NSM PM17205, holotype, from Loc. MK4030.
Scale bar5cm.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 77
Fig. 34. Gaudryceras makarovense Shigeta and Maeda, sp. nov. 1–4, Inner whorls of the holotype (NSM
PM17205, Fig. 33), from at Loc. MK4030. Scale bar2cm.
78 Haruyoshi Maeda et al.
Fig. 35. Gaudryceras makarovense Shigeta and Maeda, sp. nov. 1–2, Inner whorls of NSM PM17213, paratype,
from Loc. MK2031, 1.0. 3, NSM PM17213, paratype, from Loc. MK2031, 1.0. 4–5, NSM PM17214,
paratype, from Loc. MK2031, 1.0. 6–7, NSM PM17215, paratype, from Loc. MK2031, 1.0. 8–10, NSM
PM17216, paratype, from Loc. MK2031, 1.0.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 79
Fig. 36. Gaudryceras makarovense Shigeta and Maeda, sp. nov. 1–2, NSM PM17210, paratype, from Loc.
MK2029, 1.0. 3, NSM PM17208, paratype, from Loc. MK2025, 1.0. 4, NSM PM17209, paratype, from
Loc. MK2025, 1.0.
80 Haruyoshi Maeda et al.
Fig. 37. Gaudryceras makarovense Shigeta and Maeda, sp. nov. 1–2, NSM PM17211, paratype, from Loc.
MK2029, 0.5. 3–4, NSM PM17212, paratype, from Loc. MK2029, 0.5.
Makarov, its type locality.
Occurrence:The present specimens were
associated with Pachydiscus flexuosus in a bed
in the K3 Unit (Upper Maastrichtian) of the
Krasnoyarka Formation in the Makarov area,
Sakhalin. Specimens referable to Gaudryceras
makarovense sp. nov. were collected from the
Maastrichtian of the Pugachevo area, southern
Sakhalin, and from a float nodule probably de-
rived from the Shimonada Formation of Maas-
trichtian age on Awaji Island, southwest Japan.
Genus Anagaudryceras Shimizu 1934
Type species:Ammonites sacya Forbes, 1846.
Anagaudryceras nanum Matsumoto, 1985
Fig. 38.5–38.8
Anagaudryceras nanum Matsumoto, 1985, p. 25, pl. 5,
figs. 1–4.
Type:Holotype, GK H3124 (Matsumoto,
1986, p. 25, pl. 5, figs. 1–4), is from the Cam-
panian of the Urakawa area, central Hokkaido.
Material:NSM PM17218, from Loc.
MK2062 along the Acacia River.
Description:Very evolute shell, with a
whorl section that varies from slightly de-
pressed during the early growth stage to slight-
ly compressed as the shell matures, and a
wide, shallow umbilicus with a rounded shoul-
der. Flanks are rounded during the early
growth stages, but tend to flatten during later
growth stages, and the venter remains broadly
rounded throughout shell growth. Ornamenta-
tion consists of very fine lirae which arise at
the umbilical seam and become sinuous, ap-
proaching a slightly sigmoidal form, before
crossing over the venter in a broad, convex
arch. In addition, the last whorl is ornamented
with low, broad, gently flexed band-like ribs
which are separated by narrow constrictions.
The suture lines are not exposed.
Occurrence:The holotype of Anagaudry-
ceras nanum was found in the Sphenoceramus
schmidti Zone, of late Early Campanian age,
in the Urakawa area, central Hokkaido. The
present specimen was obtained from the Sphe-
noceramus orientalis bearing bed, just below
the Sphenoceramus schmidt bearing bed, in the
B3 Unit of the Bykov Formation in the
Makarov area, Sakhalin.
Anagaudryceras matsumotoi Morozumi, 1985
Fig. 39
Anagaudryceras matsumotoi Morozumi, 1985, p. 29, pl. 9,
fig. 1, text-fig. 7; Matsumoto, 1985, p. 27, pl. 4, figs.
1–10; Matsumoto, 1988, p 183, pl. 51, fig. 3.
Zelandites varuna (Forbes). Yazikova, 1994, p. 289, pl. 1,
fig. 8.
Type:Holotype, GK. H6882 (Morozumi,
1985, p. 29, pl. 9, fig. 1), is from the Upper
Maastrichtian on Awaji Island, southwest
Japan.
Material:NSM PM17219, from Loc.
MK2021 and NSM PM17263, from Loc.
MK2022 along the Acacia River. NSM
PM17264, from Loc. MK4014, NSM PM-
17265, from Loc. MK4015, four specimens,
NSM PM17220–17223, from Loc. MK4016,
and NSM
PM17266, from Loc. MK4018 along
the Victoria
River. Three specimens, NSM
PM17224–17226, from a float calcareous nod-
ule in the upper course of a small tributary
flowing into the Acatia River at MK2029.
Description:Species is distinguished by a
small sized mature shell, less than 60mm in
diameter. Moderately involute shell, character-
ized by a slightly depressed, rounded whorl
section during earlier growth stages, with the
greatest width occurring some distance below
mid-flank. The umbilicus is of moderate width
with a rounded umbilical wall. As growth pro-
ceeds the whorl section tends to become
slightly compressed with the last whorl being
moderately compressed. Ornamentation con-
sists of very fine lirae, which arise at the um-
bilical seam, sweep gently forwards across the
umbilical wall, shoulder and flanks, and then
pass straight across the venter. In addition, the
last whorl is ornamented with low, broad, gen-
tly flexed band-like ribs, which are separated
Stratigraphy of the Upper Cretaceous System in the Makarov Area 81
by constrictions of variable width. The suture
line is not exposed.
Remarks:Yazikova (1994) assigned a
small gaudryceratid from the Pachydiscus flex-
uosus Zone in the Pugachevo area to Ze-
landites varuna (Forbes), but the specimen is
identical to Anagaudryceras matsumotoi with
respect to whorl section, mode of coiling, and
ornamentation.
Occurrence:Gaudryceras matsumotoi oc-
curs in the Zelandites varuna bearing bed
(Upper Maastrichtian) in the Naiba and Pu-
gachevo areas, southern Sakhalin, and on
Awaji Island, southwest Japan. The species has
also been reported from the Pachydiscus flexu-
osus bearing bed (Upper Maastrichtian) in the
Nakatombetsu area, northern Hokkaido (Ando
et al., 2001), and Nemuro-Kushiro area, east-
ern Hokkaido.
The present specimens were found in the
Sphenoceramus hetonaianus (upper Lower
Maastrichtian) and Gaudryceras makarovense
sp. nov. (Upper Maastrichtian) bearing beds in
the K2 and K3 units of the Krasnoyarka For-
mation in the Makarov area, Sakhalin.
Anagaudryceras seymouriense Macellari,
1986
Figs. 40.4–40.6, 41
Anagaudryceras seymouriense Macellari, 1986, p. 10, figs.
9.1–9.6, 10.1–10.4.
Anagaudryceras cf. seymouriense Macellari. Matsumoto,
1988, p. 183, pl. 51, fig. 2, pl. 53, fig. 1.
Type:Holotype, OSU38333 (Macellari,
1986, p. 10, fig. 9.1–9.2), is from the Upper
Maastrichtian of Seymour Island in the
Antarctic Peninsula.
Material:NSM PM17238, from Loc. MK
-
4016 along the Victoria River in the Makarov
area.
Description:Very evolute shell, distin-
guished by slowly expanding whorls, and a
slightly depressed whorl section during the
early growth stages, but becoming moderately
compressed upon reaching maturity, and a
wide, shallow umbilicus with a steep wall and
moderately rounded shoulder. The sides are
slightly flattened and the venter is rounded.
Ornamentation consists of very fine lirae,
which arise at the umbilical seam and become
slightly flexuous, approaching a slightly sig-
moidal form, before passing over the venter in
a broad, convex arch. In addition, periodic nar-
row, rounded collar-like or fold-like ribs occur
on the mature whorls. The suture lines are not
exposed.
Occurrence:Macellari (1986) originally
described Anagaudryceras seymouriense, of
late Maestrichtian age, from a level just below
the horizon at which Zelandites varuna occurs
on Seymour Island. Matsumoto (1988) also
described a specimen comparable to the pres-
ent species, from the Rdy Member of the Ryu-
gase Group, from a locality in the Naiba area,
southern Sakhalin. Although the Ryugase
Group is no longer recognized, the Rdy Mem-
ber is equivalent to the K4 Unit of the Krasno-
yarka Formation, as defined by Kodama et al.
(2002), and it includes the Z. varuna bearing
bed in the Naiba area, southern Sakhalin.
The present specimens were found in the
Sphenoceramus hetonaianus bearing bed in
the K2 Unit of the Krasnoyarka Formation,
which is equivalent to the upper Lower to
lower Upper Maastrichtian, in the Makarov
area, Sakhalin.
82 Haruyoshi Maeda et al.
Fig. 38. 1–4, Zelandites varuna (Forbes), NSM PM17217, from a float calcareous nodule at Loc. MK3031,
2.0. The specimen is almost certainly from the mudstone of the K2 Unit of the Krasnoyarka Formation. 5–8,
Anagaudryceras nanum Matsumoto, NSM PM17218, from Loc. MK2062, 2.0. 9–11, 14–15, Tetragonites
popetensis Yabe. 9–11, NSM PM17230, from Loc. MK2021, 2.0. 14–15, NSM PM17236, from Loc.
MK4014, 2.0. 12–13, 16–17, Pseudophyllites indra (Forbes). 12–13, NSM PM17247, from Loc. MK2031,
2.0. 16–17, NSM PM17242, from Loc. MK4016, 2.0.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 83
Genus Zelandites Marshall, 1926
Type species:Zelandites kaiparaensis
Marshall, 1926.
Zelandites varuna (Forbes, 1846)
Fig. 38.1–38.4
Ammonites varuna Forbes, 1846, p. 107, pl. 8, fig. 5.
Lytoceras (Gaudryceras) varuna (Forbes). Kossmat, 1895,
p. 161, pl. 16, fig. 4, pl. 17, fig. 8.
Lytoceras varuna (Forbes). Steinmann, 1895, p. 84, pl. 5,
fig. 2, text-fig. 7.
Zelandites varuna (Forbes) var. japonica Matsumoto,
1938, p. 140, pl. 14, figs. 5–7, text-fig. 1.
Zelandites cf. varuna (Forbes). Morozumi, 1985, p. 32, pl.
9, fig. 2, text-fig. 8.
Zelamdites varuna (Forbes). Stinnisbeck, 1986, p. 195, pl.
8, figs. 5–6, text-fig. 20; Macellari, 1986, p. 14, text-
figs. 11.11, 11.12, 12; Matsumoto, 1988, p. 184, pl. 51,
fig. 4; Kennedy and Henderson, 1992, p. 404, pl. 5, figs.
13–15, pl. 17, figs. 2–3.
Zelandites japonicus Matsumoto. Yazikova, 1994, p. 290,
pl. 1, figs. 1–4, pl. 2, figs. 1–18; Alabushev and Wied-
mann, 1997, p. 11, pl. 2, fig. 6, text-fig. 2.
Type:Lectotype, designated by Matsumo-
to (1988, p. 184), is BMNH C51059, the origi-
nal of Forbes (1846, p. 107, pl. 8, fig. 5) from
the Upper Maastrichtian of Pondicherry,
southern India.
Material:NSM PM17217, extracted from
a float calcareous nodule at Loc. MK3031
along the Gruzovka River.
Description:Very involute shell, charac-
terized by a compressed whorl section, with
the greatest width below mid-flank, and a nar-
row umbilicus with a low, rounded wall. The
inner flanks are broadly rounded, and the outer
flanks converge to a narrowly rounded venter.
The specimen retains none of the original or-
namentation. The suture line is not exposed.
Occurrence:Zelandites varuna occurs in
the Upper Maastrichtian of southern India,
Chili, Seymour Island in Antarctica and Awaji
Island in Southwest Japan. It also occurs in the
Pachydiscus subcompressus bearing bed
(Upper Maastrichtian) in the Nakatombetsu
area, northern Hokkaido (Ando et al., 2001)
and the Naiba area, southern Sakhalin.
The present specimen was obtained from a
float calcareous nodule at Loc. MK3031 along
the Gruzovka River in the Makarov area,
Sakhalin. Although the exact horizon from
which the nodule came is uncertain, judging
from the locality and the lithology, it almost
without doubt came from the mudstone in the
K2 Unit of the Krasnoyarka Formation. This
horizon probably occurs between the Spheno-
ceramus hetonaianus bearing bed (upper
Lower Maastrichtian) and the Gaudryceras
makarovense sp. nov. bearing bed (Upper
Maastrichtian).
Family Tetragonitidae Hyatt, 1900
Genus Tetragonites Kossmat, 1895
Type species:Ammonites timotheanus Pictet,
1848.
Tetragonites glabrus (Jimbo, 1894)
Fig. 42.1–42.4
Lytoceras glabrum Jimbo, 1894, p. 180, pl. 22, fig. 2.
Lytoceras sphaeronotum Jimbo, 1894, p. 181, pl. 22, fig.
4.
Lytoceras crassum Jimbo, 1894, p. 181, pl. 22, fig. 5.
Tetragonites glabrus (Jimbo). Yabe, 1903, p. 43, pl. 7, figs.
2, 5; Matsumoto, 1959b, p. 149, pl. 39, figs. 2–3, text-
figs. 72–73; Tanabe and Kanie, 1978, p. 8, pl. 1, fig. 2;
Shigeta, 1989, p. 334, text-fig. 12 (1–2).
Tetragonites sphaeronotus (Jimbo). Yabe, 1903, p. 45, pl.
7, fig. 1.
84 Haruyoshi Maeda et al.
Fig. 39. Anagaudryceras matsumotoi Morozumi. 1–2, NSM PM17220, from Loc. MK4016, 1.0. 3, NSM
PM17221, from Loc. MK4016, 1.0. 4–6, NSM PM17222, from Loc. MK4016, 1.0. 7, NSM PM17223,
from Loc. MK4016, 1.0. 8–9, NSM PM17219, from Loc. MK2021, 1.0. 10–11, NSM PM17224, from a
float calcareous nodule in the upper course of a small tributary flowing into the Acatia River at Loc. MK2029,
1.0. 12–13, NSM PM17225, from the same nodule as NSM PM17224, 1.0. 14–15, NSM PM17226, from
a floated calcareous nodule in the upper course of a small tributary flowing into the Acatia River at Loc.
MK2029, 1.0.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 85
86 Haruyoshi Maeda et al.
Fig. 40. 1–3, Gaudryceras cf. tombetsense Matsumoto, NSM PM17251, from Loc. MK4016, 1.0. 4–6, Ana-
gaudryceras seymouriense Macellari, inner whorls of NSM PM17238, from Loc. MK4016, 1.0.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 87
Fig. 41. Anagaudryceras seymouriense Macellari. 1–4, NSM PM17238, from Loc. MK4016, 0.55.
Tetragonites cf. epigonus Kossmat. Yabe, 1903, p. 49, pl.
7, fig. 3.
Epigoniceras glabrum (Jimbo) var. problematica Mat-
sumoto, 1942b, p. 672, fig. 1.
Epigoniceras epigonum (Kossmat). Alabushev and Wied-
mann, 1997, p. 8, pl. 1, figs. 8–11, text-fig. 1.
Type:Holotype, UMUT MM7513 (Jimbo,
1894, p. 180, pl. 22, fig. 2), from the Upper
Cretaceous of Ikandai in the Urakawa area,
central Hokkaido.
Material:NSM PM17227, from Loc. MK-
2062
along the Acacia River.
Description:Involute shell, characterized
by moderately expanding whorls, a slightly de-
pressed, sub-quadrate whorl section, and a nar-
row, deep umbilicus with a steep wall and an
abruptly rounded shoulder on younger whorls,
becoming more rounded on mature whorls.
The flanks are gently rounded, merging with
rounded ventrolateral shoulders and a broadly
rounded venter. Although the shell surface is
nearly smooth, it does have very fine, prorsira-
diate growth lines and parallel, infrequent,
conspicuous rib-like elevations that pass over
the inner part of the umbilical wall and flanks,
before becoming slightly flexuous at the ven-
trolateral shoulder and passing over the venter
in a broad, adapical facing curve. The suture
line is not exposed.
Remarks:Based on a large sample of
specimens collected from the upper Campan-
ian in the Soya area, Shigeta (1989) noted that
Tetragonites glabrus exhibits a remarkable
variation in shell form. However, at a later
date Shigeta (1992) described Pseudophyllites
indra (Forbes) from Hokkaido and Sakhalin,
and pointed out that his Soya area specimens
with the small umbilicus, that he assigned to T.
glabrus in his 1989 paper, actually should be
regarded as juvenile specimens of P. i ndra.
Shigeta’s sample (AW1001A) was heteroge-
neous and consisted of specimens of both P.
indra and Tetragonites having a wide umbili-
cus, that are now referable to T. popetensis.
Therefore, T. glabrus does not occur in the
Upper Campanian of Hokkaido and Sakhalin,
and the species, in fact, does not exhibit the
enormous variation in shell form described
above. However, as Shigeta (1989) concluded,
the previously described species Tetragonites
sphaeronotus (Jimbo, 1894), Tetragonites
crassus (Jimbo, 1894), and Tetragonites glabu-
rus problematicus (Matsumoto, 1942b) are
identical to T. glaburus with respect to whorl
section, mode of coiling, and ornamentation,
and all should be regarded as synonyms of T.
glaburus.
Occurrence:Tetragonites glaburus occurs
in abundance from the Turonian to the Lower
Campanian in Hokkaido and Sakhalin (Ma-
tsumoto, 1942d, 1943; Toshimitsu & Hirano,
2000). The species is also known from the
Santonian to the Campanian of Northwestern
Kamchatka.
The present specimens were found in the
Sphenoceramus orientalis bearing bed (upper
Lower Campanian) just below the Sphenocera-
mus schmidti bearing bed in the B3 Unit of the
Bykov Formation in the Makarov area,
Sakhalin.
Tetragonires popetensis Yabe, 1903
Figs. 38.9–38.11, 38.14–38.15, 42.5–42.11, 43, 44
Tetragonites popetensis Yabe, 1903, p. 48, pl. 7, figs. 4, 6;
Matsumoto and Miyauchi, 1984, p. 52, pl. 23, fig. 3;
Matsumoto, 1988, p. 178, pl. 50, figs, 3–4; Yazikova,
1994, p. 293, pl. 3, fig. 1.
Tetragonites glaburus (Jimbo). Shigeta, 1989, p. 334, text-
fig. 12 (4–7).
Type:Holotype, UMUT MM7460 (Yabe,
1903, p. 48, pl. 7, fig. 4), is from the Upper
Cretaceous of Sanushibe in the Hobetsu area,
central Hokkaido.
Material:NSM PM17228, from Loc. MK-
4004
and two specimens, NSM PM17236,
17237, from Loc. MK4014 along the Victoria
River. PM17229, from a float calcareous
nodule, (also containing Sphenoceramus
schmidti), found along a small tributary flow-
ing into the Victoria River at MK4047. Three
specimens, NSM PM17231–17233, from
88 Haruyoshi Maeda et al.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 89
Fig. 42. 1–4, Tetragonites glabrus (Jimbo, 1894), NSM PM17227, from Loc. MK2062, 1.0. 5–11, Tetragonites
popetensis Yabe. 5–8, NSM PM17228, from Loc. MK4004, 1.0. 9–11, NSM PM17229, associated with a
specimen of Sphenoceramus schmidti (Michael) in a float calcareous nodule found along a small tributary
flowing into the Victoria River at Loc. MK4047, 1.0.
Loc. MK2015 and two specimens, NSM
PM17234, 17235, from Loc. MK2014 along
the Acacia River. NSM PM17230, from Loc
MK2021 along the Acacia River.
Description:Moderately involute shell, cha-
racterized
by moderately expanding whorls, a
slightly depressed, rounded to sub-quadrate
whorl section, and an umbilicus of moderate
width with a very steep, moderately high wall
and a rounded shoulder. Gently curved flanks
and rounded ventrolateral shoulders merge
with a broadly rounded venter. Very fine
growth lines, visible on an otherwise nearly
smooth shell surface, are prorsiradiate on the
flanks, but become slightly sinuous at the ven-
trolateral shoulders, before passing across the
venter in a broad, adapical facing curve. Peri-
odic, conspicuous rib-like elevations (60–80°),
parallel to the growth lines, also occur, but
specimens NSM PM17231–17233 (Fig. 43)
are unique in that the last constriction is very
close (20°) to the aperture. The suture line,
with its trifid major saddles and bifid
lateral lobe, is typical of Tetragonitids.
Remarks:Shigeta (1989) regarded Tetrago-
nites
popetensis as a synonym of Tetragonites
glaburus, but as discussed above in the re-
marks section for T. glaburus, both are suffi-
ciently distinct so as to be considered different
species.
Occurrence:Tetragonites popetensis oc-
curs in abundance in sediments ranging in age
from the Santonian to the Maastrichtian in
Hokkaido and Sakhalin (Matsumoto, 1942d,
1943; Toshimitsu & Hirano, 2000). The pres-
ent specimens were collected from the Sphe-
noceramus schmidti bearing bed in the B4
Unit of the Bykov Formation and the Spheno-
ceramus hetonaianus bearing bed in the K2
Unit of the Krasnoyarka Formation, as well as
from several horizons in between, in the
Makarov area, Sakhalin. They range in from
the upper Lower Campanain to the upper
Lower Maastrichtian.
Genus Saghalinites Wright
and Matsumoto, 1954
Type species:Ammonites cala Forbes, 1846.
Saghalinites teshioensis Matsumoto, 1984a
Fig. 45
Saghalinites teshioensis Matsumoto, 1984a, p. 27, pl. 9,
figs. 1–3; Matsumoto, 1988, p. 179, pl. 51, fig. 1.
Type:Holotype, GK. H5971 (Matsumoto,
1984a, p. 27, pl. 9, fig. 1), is from the Upper
Campanian of Uttsu in the Teshio Mountains,
northern Hokkaido.
Material:Three specimens, NSM PM-
17239–17241, from Loc. MK2014 along the
Acacia River. All specimens are slightly
crushed and deformed.
Description:Very evolute shell, character-
ized by slowly expanding whorls, a slightly de-
pressed whorl section during early growth
stages, becoming slightly compressed as diam-
eter increases, and a wide, shallow umbilicus
with a low, rounded wall. On mature whorls,
the flanks are gently rounded while the venter
is more narrowly rounded. Fine growth lines,
visible on a nearly smooth shell surface, arise
at the umbilical seam and sweep forward over
the inner flanks, become slightly sinuous at
mid-flank, and then pass over the venter in a
broad, adapical facing curve. Periodic, distant
constrictions (60–80°) occur on the adult body
chamber, but specimen NSM PM17239 is
unique in that the last constriction is very
close (20°) to the aperture. The suture line is
not exposed.
Occurrence:Saghalinites teshioensis oc-
curs in the Schlueterella kawadai bearing bed,
of late Campanian age, in the Naiba area,
Sakhalin and the Teshio Mountains, Hokkaido.
90 Haruyoshi Maeda et al.
Fig. 43. Tetragonites popetensis Yabe. 1–3, NSM PM17231, from Loc. MK2015, 1.0. 4–6, NSM PM17232,
from Loc. MK2015, 1.0. 7–9, NSM PM17233, from Loc. MK2015, 1.0.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 91
92 Haruyoshi Maeda et al.
Fig. 44. Tetragonites popetensis Yabe. 1–4, NSM PM17237, from Loc. MK4014, 1.0. 5–7, NSM PM17234,
from Loc. MK2014, 1.0. 8–10, NSM PM17235, from Loc. MK2014, 1.0.
Fig. 45. Saghalinites teshioensis Matsumoto. 1–4, NSM PM17239, from Loc. MK2014, 1.0. 5–6, NSM
PM17240, from Loc. MK2014, 1.0. 7–9, NSM PM17241, from Loc. MK2014, 1.0.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 93
The present specimens were associated with S.
kawadai in a bed in the K1 Unit of the Kras-
noyarka Formation in the Makarov area,
Sakhalin.
Genus Pseudophyllites Kossmat, 1895
Type species:Ammonites indra Forbes, 1846.
Pseudophyllites indra (Forbes, 1846)
Figs. 38.12, 38.13, 38.16, 38.17, 46–50
Ammonites indra Forbes, 1846, p. 105, pl. 11, fig. 7;
Stoliczka, 1865, p. 112, pl. 58, fig 2; Whiteaves 1879,
p. 105, pl. 13, fig. 2.
Pseudophyllites indra (Forbes). Kossmat, 1895, p. 137, pl.
16, figs. 6–9, pl. 17, figs. 6–7, pl. 18, fig. 3; Whiteaves,
1903, p. 331; Woods, 1906, p. 334, pl. 41, fig. 6; Spath,
1922, p. 119; Collignon, 1938, p. 24, text-fig. E; Usher,
1952, p. 57, pl. 3, figs. 2–13, pl. 31, figs. 15–17; Col-
lignon, 1956, p. 90; Matsumoto, 1959b, p. 134; Jones,
1963, p. 25, pl. 7, figs. 6–7, pl. 8, pl. 29, figs. 7–12,
text-fig. 10; Collignon, 1969, p. 12, pl. 516, fig. 2032;
Kennedy and Klinger, 1977, p. 182, text-figs. 19–22;
Matsumoto and Miyauchi, 1984, p. 54, pl. 21, fig. 5;
Henderson and McNamara, 1985, p. 50, pl. 2, figs. 7–8,
pl. 3, figs. 4–5, text-fig. 5; Kennedy, 1986, p. 19, pl. 1,
figs. 1–5, text-figs. 4e, 5a, 6a–e; Kennedy and Hender-
son, 1992, p. 398, pl. 3, figs. 7–9, 13–27, pl. 4, figs.
1–3; Shigeta, 1992, p. 1158, text-figs. 1–4.
Pseudophyllites cf. indra (Forbes). Kennedy and Summes-
berger, 1986, p. 187, pl. 1, figs. 1, 8, pl. 3, fig. 5, text-
fig. 4.
Tetragonites glabrus (Jimbo). Shigeta, 1989, p. 334, text-
fig. 12(3).
Type:Lectotype, designated by Kennedy
and Klinger (1977, p. 182), is BMNH C51068,
the original of Forbes (1846, p. 105, pl. 11, fig.
7) from the Upper Maastrichtian of the Valu-
davur Formation near Pondicherry, southern
India.
Material:Three specimens, NSM PM-
17248–17250, from Loc. MK4014, NSM PM-
17267, from Loc. MK4015, two specimens,
NSM PM17242, 17243, from Loc. MK4016,
and three specimens, NSM PM17244–17246,
from Loc. MK4018 along the Victoria River.
NSM PM17247, from Loc. MK2031 along the
Acacia River.
Description:Early whorls (up to 20mm).
Involute shell, characterized by moderately ex-
panding whorls, a slightly depressed, sub-
rounded to sub-quadrate whorl section, and a
narrow, deep umbilicus with a very steep wall
and rounded shoulder. Gently curved flanks
merge with broadly rounded ventrolateral
shoulders and a rounded venter. Fine, prorsira-
diate growth lines arise on the umbilical wall
and pass over the shoulder and the flanks be-
fore becoming slightly flexuous on the ventro-
lateral shoulders, and then pass over the venter
in a broad, adapical facing curve.
Middle and later whorls (over 20mm in di-
ameter). As shell matures it becomes more in-
volute and the whorl expansion rate increases
significantly. Mature whorls are characterized
by a rounded to sub-quadrate whorl section,
with the greatest width at junction of umbilical
shoulder and inner flank. Umbilicus becomes
narrower and deeper, with a broadly rounded
shoulder. Flanks are gently convex and merge
with a broad, rounded venter. Fine growth
lines, visible on the smooth shell surface, arise
on the umbilical wall and become prorsiradi-
ate as they pass over the umbilical shoulder
and flanks, but become flexuous on the ventro-
lateral shoulders and then pass across the ven-
ter with a very broad adapical facing curve. As
size increases, delicate folds appear on the
flanks and venter, paralleling the growth lines.
The suture is highly subdivided with a large,
irregularly trifid, first lateral saddle, a smaller,
bifid, second latertal saddle, a deeply incised,
bifid lateral lobe, and a suspensive lobe with a
large bifid first auxiliary saddle.
Occurrence:The present specimens were
obtained from the Sphenoceramus hetonaianus
bearing bed and the Pachydiscus flexuosus
bearing bed in the K2 and K3 units of the
Krasnoyarka Formation in the Makarov area,
Sakhalin. These beds range from the upper
Lower to the Upper Maastrichtian. Shigeta
(1992) described Pseudophyllites indra from
the Upper Campanian in the Soya area, north-
ern Hokkaido, and the Naiba area, southern
Sakhalin. However, this species has not been
94 Haruyoshi Maeda et al.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 95
Fig. 46. Pseudophyllites indra (Forbes). 1–2, NSM PM17248, from Loc. MK4014, 1.0. 3, NSM PM17249,
from Loc. MK4014, 1.0. 4–5, NSM PM17250, from Loc. MK4014, 1.0.
96 Haruyoshi Maeda et al.
Fig. 47. Pseudophyllites indra (Forbes). 1–4, NSM PM17243, from Loc. MK4016, 0.55.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 97
Fig. 48. Pseudophyllites indra (Forbes). 1–3, NSM PM17244, from Loc. MK4018, 0.5.
98 Haruyoshi Maeda et al.
Fig. 49. Pseudophyllites indra (Forbes). 1–3, NSM PM17245, from Loc. MK4018, 0.45.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 99
Fig. 50. Pseudophyllites indra (Forbes). 1–2, NSM PM17246, from Loc. MK4018, 0.3.
reported from the Inoceramus shikotanenus
Zone, of the lower Lower Maastrichtian in
Hokkaido and Sakhalin, in spite of its rich am-
monite fauna.
P. i ndra is a long ranging, cosmopolitan
species known from the Santonian to Upper
Maastrichtian in southern India, South Africa,
Madagascar, Western Australia, Hokkaido,
Sakhalin, Alaska, British Columbia, Califor-
nia, Chili, Poland, Austria and France.
Suborder Ancyloceratina, Wiedmann, 1966
Superfamily Turrilitoidea, Gill, 1871
Family Baculitidae Gill 1871
Genus Baculites Lamarck, 1799
Type species:Baculites vertebralis Lamar-
ck, 1801
Baculites sp.
Fig. 51.4–51.7
Material:NSM PM17252, from the upper-
most
part of the Bykov Formation at Loc.
MK2015 along the Acacia River. Specimen is
a fragment of a body chamber.
Description:Slowly tapered shell, charac-
terized by an oval whorl section, with a nar-
rowly rounded venter and a broadly rounded
dorsum, with the greatest width at a position
just slightly dorsal of mid-flank. Shell surface
is nearly smooth. Specific identification is im-
possible because of extremely poor preserva-
tion.
Occurrence:The present specimen was
associated with Canadoceras kossmati (upper
part of the Lower Campanian) in a bed just
below the Schlueterella kawadai bearing bed
(Upper Campanian) in the B4 Unit of the
Bykov Formation in the Makarov area,
Sakhalin.
Family Diplomoceratidae Spath, 1926
Genus Schlueterella Wiedmann, 1962
Type species:Ancyloceras pseudoarmatum
Schlüter, 1872
Schlueterella kawadai Matsumoto and
Miyauch, 1984
Fig. 51.8–51.13
Hamites cf. amartus Sowerby. Kawada, 1934, pl. 7, fig.
15, pl. 8, fig. 16.
Schlueterella kawadai Matsumoto and Miyauchi, 1984, p.
61, pl. 26, fig. 1, pl. 27, figs. 3–4, pl. 28, fig. 2, pl. 29,
fig. 1, pl. 30, figs. 1–2, pl. 31, fig. 3, text-fig. 9.
Type:Holotype, GK. H5978 (Matsumoto
& Miyauch, 1984, p. 61, pl. 26, fig. 1), is from
Upper Campanian beds around the Soya fish-
ing harbour in the Soya area, northern Hokkai-
do.
Material:Two specimens, NSM PM17253,
17254, from Loc. MK2014 along the Acacia
River. PM17253 is a partly deformed, slightly
curved portion of a phragmocone.
Description:Shell surface is ornamented
with numerous ribs, which are slanted forward
when viewed laterally. Periodic major ribs en-
circle the shell and each rib is ornamented
with four spinose tubercles, one on each side
of the ventral zone and one at mid-flank on
each side. The sutures lines are only partly ex-
posed on PM17253.
PM17254 is a curved portion of a large
shell and it probably represents the hooked
part of the body chamber. Only the ventral
part is preserved, and two rows of tubercles are
visible on the major ribs. Ornamentation on
the ventral area is identical to that on the
type material described by Matsumoto and
100 Haruyoshi Maeda et al.
Fig. 51. 1–3, Glyptoxoceras sp., NSM PM17255, from Loc. MK2036, 1.0. 1, Plaster cast from outer mould. 2,
Lateral view. 3, Lateral view. 4–7, Baculites sp., NSM PM17252, from Loc. MK2015, 1.0. 4, Lateral view.
5, Ventral view. 6, Lateral view. 7, Dorsal view. 8–13, Schlueterella kawadai Matsumoto and Miyauch. 8–11,
NSM PM17253, from Loc. MK2014, 1.0. 8, Lateral view. 9, Ventral view. 10, Lateral view. 11, Dorsal view.
12–13, NSM PM17254, from Loc. MK2014, 1.0. 12, Lateral view. 13, Ventral view.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 101
Miyauch (1984).
Occurrence:Schlueterella kawadai is abun-
dant
in the Menuites soyaensis bearing bed
(Upper Campanian) in the Soya area, northern
Hokkaido and the Naiba area, southern
Sakhalin, as well as the Metaplacenticeras
subtilistriatum bearing bed in the Teshio
Mountains, northern Hokkaido. The present
specimens were collected from the M. soyaen-
sis bearing bed in the K1 Unit of the Krasno-
yarka Formation in the Makarov area,
Sakhalin.
Genus Diplomoceras Hyatt, 1900
Type species:Baculites cylindracea De-
france, 1816.
Diplomoceras cf. notabile Whiteaves, 1903
Fig. 52
cf. Diplomoceras notabile Whiteaves, 1903, p. 335, pl. 44,
fig. 4; Usher, 1952, p. 109, pl. 29, fig. 2, pl. 30, fig. 1,
pl. 31, figs. 26–27; Jones, 1963, p. 32, pl. 21, fig. 1,
text-fig. 15.
cf. Diplomoceras cf. notabile Whiteaves. Matsumoto and
Morozumi, 1980, p. 23, pl. 16, fig. 3.
Material:NSM PM17256, from Loc. MK-
4030
along the Victoria River. Specimen is
slightly flattened.
Description:PM17256 is a large portion
of a body chamber approximately 330mm
long and 190mm wide. It consists of two
straight, nearly parallel shafts connected by U-
curve. The whorl section is broadly oval with a
nearly flattened dorsal side and a more nar-
rowly rounded ventral side. Ornamentation
consists of numerous, regularly spaced, encir-
cling ribs, which vary from straight to strongly
oblique.
Discussion:Although the present speci-
men is a partly deformed body chamber, its
distinctive features enable us to identify it with
probable confidence as Diplomoceras notabile.
Occurrence:Diplomoceras notabile is known
from beds of late Campanian to Maastrichtian
age in southwestern Japan, Alaska and British
Columbia. The present specimens were associ-
ated with Pachydiscus flexuosus in a bed in the
K3 Unit (lower Upper Maestrichtian) of the
Krasnoyarka Formation in the Makarov area,
Sakhalin.
Genus Glyptoxoceras Spath, 1925
Type species:Hamites rugatus Forbes, 1846.
Glyptoxoceras sp.
Fig. 51.1–51.3
Material:NSM PM17255, from Loc. MK-
2036
along the Acacia River.
Description:The whorl is in the form of a
very loose helix, with a slightly compressed,
subcircular whorl section. Ornamentation con-
sists of very fine, delicate ribs, which vary
from straight to oblique. The suture lines are
not exposed.
Occurrence:The present specimen was
collected from the Pachydiscus flexuosus bear-
ing bed in the K3 Unit (lower Upper Maas-
trichtian) of the Krasnoyarka Formation in the
Makarov area, Sakhalin.
Suborder Ammonitina Hyatt, 1889
Superfamily Desmocerataceae Zittel, 1895
Family Desmoceratidae, 1895
Genus Damesites Matsumoto, 1942a
Type species:Desmoceras damesi Jimbo,
1894.
Damesites cf. sugata (Forbes, 1846)
Fig. 53.1–53.6
cf. Ammonites sugata Forbes, 1846, p. 113, pl. 10, fig. 2.
cf. Damesites sugata (Forbes). Matsumoto and Obata,
1955, p. 128, pl. 26, figs. 4–5, pl. 27, figs. 3–4; Haggart,
1989, p. 195, pl. 8.4, figs. 14–23.
Material:Two specimens, NSM PM17257,
17258, from the Bykov Formation at Loc.
MK2062 along the Acacia River.
Description:Very involute shell, charac-
102 Haruyoshi Maeda et al.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 103
Fig. 52. Diplomoceras cf. notabile Whiteaves, NSM PM17256 from Loc. MK4030. Scale bar5cm.
terized by an oval to sub-quadrate, slightly
compressed whorl section, and weakly convex,
nearly parallel flanks, with the greatest whorl
width at about mid-flank, and a narrow, deep
umbilicus with a vertical wall and rounded
shoulder. The present specimens display very
weak keel on a rounded venter. Fine, prorsira-
diate growth lines, cover most of the flank, and
flex forward at the ventrolateral shoulder, be-
fore crossing the venter with a narrow, convex
arch. In addition, distant, periodic constric-
tions occur on all whorls. The suture line is
typical of desmoceratids.
Discussion:Even though the present spec-
imens are small, their distinctive features en-
able us to identify them with probable confi-
dence as Damesites sugata.
Occurrence:The present specimens were
found in the Sphenoceramus orientalis bearing
bed (upper Lower Campanian) in the B3 Unit
of the Bykov Formation in the Makarov area,
Sakhalin. Damesites sugata is abundant in
beds of Coniacian to Campanian age in
Hokkaido, Sakhalin, British Columbia and
southern India.
Genus Desmophyllites Spath, 1929
Type species:Desmoceras larteti Seunes,
1891.
Desmophyllites diphylloides (Forbes, 1846)
Fig. 53.7–53.14
Ammonites diphylloides Forbes, 1846, p. 105, pl. 8, fig. 8.
Desmophyllites diphylloides (Forbes). Matsumoto and
Obata, 1955, p. 121, pl. 24, figs. 1–5, pl. 30, fig. 1, text-
fig. 1; Matsumoto, 1959b, p. 9, pl. 3, fig. 3, text-fig. 2;
Collignon, 1961, p. 61, pl. 25, figs. 1–2, text-fig. 2;
Howarth, 1965, p. 388, pl. 11, fig. 3; Collignon, 1966,
p. 84, pl. 498, fig. 1973; Collignon, 1971, p. 37, pl. 655,
fig. 2415; Matsumoto, 1984a, p. 12, pl. 1, fig. 2; Hen-
derson and McNamara, 1985, p. 54, pl. 4, figs. 1–4;
Haggart, 1989, p. 193, pl. 8.4, figs. 1–13; Kennedy and
Henderson, 1992, p. 405, pl. 6, figs. 1–9, pl. 16, figs.
1–3, 7–8, pl. 17, figs. 4–7, text-fig. 3F; Alabushev and
Wiedmann, 1977, p. 22, pl. 6, figs. 3–5.
Type:Lectotype, designated by Matsumo-
to and Obata (1955, p. 122), is BMNH
C22682, the original of Forbes (1846, p. 105,
pl. 8, fig. 8) from the Maastrichtian (?) of
Pondicherry, southern India.
Material:Three specimens, NSM PM-
17259–17261, from Loc. MK2014 along the
Acacia River. All specimens are slightly
crushed and deformed.
Description:Very involute shell character-
ized by an oval to sub-quadrate, slightly com-
pressed whorl section, a very narrow, deep
umbilicus, and a moderately rounded venter at
an early growth stage, but becoming narrowly
rounded on mature whorls. Fine growth lines
arise on the umbilical shoulder, become slight-
ly sigmoidal in shape on the inner flank, and
bend sharply forward on the outer flank before
crossing venter in a narrow, convex arch. In
addition, distant, periodic constrictions, paral-
lel to the growth lines, occur on all whorls.
The sutures lines are only partly exposed.
Occurrence:Desmophyllites diphylloides
is known from beds of Santonian to late Maas-
trichtian age in southern India, western Aus-
tralia, Madagascar and Angola, and it has also
been reported from the Schluterella kawadai
bearing bed (Upper Campanian) in southern
Sakhalin and northern Hokkaido. The present
specimens were associated with Schluterella
kawadai in a bed in the K1 Unit of the Kras-
noyarka Formation in the Makarov area,
Sakhalin.
Concluding remarks
The Russian-Japanese joint investigation
has delineated the detailed stratigraphy as well
as the faunal succession in the Makarov area.
Final conclusions regarding stratigraphic cor-
relation will be presented after all analyses are
completed and integrated.
The Cretaceous System in the Far East re-
gion is widely regarded as one of the world’s
standards (Matsumoto, 1977; Pergament,
1977). It reveals prolific information about
104 Haruyoshi Maeda et al.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 105
Fig. 53. 1–6, Damesites cf. sugata (Forbes). 1–4, NSM PM17257, fom Loc. MK2062, 1.0. 5–6, NSM
PM17258, fom Loc. MK2062, 1.0. 7–14, Desmophyllites diphylloides (Forbes). 7, NSM PM17259, from
Loc. MK2014, 1.0. 8–11, NSM PM17260, from Loc. MK2014, 1.0. 12–14, NSM PM17261, from Loc.
MK2014, 1.0.
biogeography as well as pandemic environ-
mental changes during Cretaceous time, e.g.,
Oceanic Anoxic Events (Hirano et al., 1991;
Hirano, 1995). Several new paleoecological
approaches have also arisen from observations
of Cretaceous fossil assemblages from
Hokkaido and Sakhalin (Kase et al., 1994;
Maeda, 1987, 1991, 1993; Shigeta, 1993).
Therefore, much further progress is anticipat-
ed as a result of future efforts by the joint re-
search team.
Acknowledgments
We are very much grateful to K. F. Sergeev,
Director of the Institute of Marine Geology
and Geophysics, Yuzhno-Sakhalinsk, and G.
S. Steinberg, Director of the Institute of
Volcanology and Geodynamics, Yuzhno-
Sakhalinsk, for their supervision of this re-
search program. We also thank the various
staff personnel of the Institute for their kind
help and cooperation throughout the field sur-
vey. A. V. Solov’yov (Institute of Volcanology
and Geodynamics) and members of the Joint-
Research Program, T. Kase and K. Uemura
(National Science Museum), K. Kodama
(Kochi University), T. Okamoto (Ehime Uni-
versity), T. Hasegawa (Kanazawa University),
M. Futakami (Kawamura Women’s Universi-
ty), and T. Takeuchi (Anjo Gakuen High
School) gave us kind advice and help during
the course of this study in various ways.
Thanks are also extended to the Mayor and
other area authorities, as well as the citizens of
Makarov, and the State Government of
Sakhalin for their assistance during the work.
This study was financially supported by the
Ministry of Education, Science, Culture, and
Sports, Japanese Government (Project Nos.
5041068, 8041113 and 9041114), and by the
Fujiwara Natural History Foundation’s support
of H.M. (Project No. 12-3) and Y.S. (Project
No. 7-21).
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Stratigraphy of the Upper Cretaceous System in the Makarov Area 111
ロシア極東・サハリン南部・マカロフ地域の白亜系層序と化石群:マカロフ地域の白亜系
蝦夷層群について,層序学および古生物学の視点から包括的な調査研究を行った.本地域に
分布する蝦夷層群は,サントニアン期からマストリヒチアン期に及び,層厚は 2,500 m に達
する.下位からブイコフ層とクラスノヤルカ層に区分される.ブイコフ層は主に沖合成の泥
岩から成り,下位から B1B4 4岩相ユニットに区分される.一方,クラスノヤルカ層は主
に沿岸成の砂岩やデルタ堆積物から成り,下位から K1K4b 5岩相ユニットに区分される.
クラスノヤルカ層の最上部を除き,化石は豊富に産出する.特に,パキディスクス科,テト
ラゴニテス科,ゴードリセラス科のアンモノイドが豊富に産出する.Sphenoceramus schmidti
(カンパニアン期中期)も多産し,特徴的な化石帯として広く追跡できる.国際対比に有効な
属種の産出は少ないが,カンパニアン期からマストリヒチアン期までのほぼ完全な化石群
が連続的に観察できることは注目される.蝦夷層群の化石群の組成や泥岩の堆積学的な特
徴はサハリン南部や北海道を通じて似ている.幾つかの化石帯は岩相層序境界と斜交する
が,同一の岩相や生物相が南北 1,200 km にわたり分布する.このような堆積や動物群の均質
性は蝦夷層群の著しい特徴である.本論文では,Hypophylloceras (Neophylloceras) victriense
Gaudryceras makarovens 2新種を含む 14 25 種のアンモノイドを記載した.
前田晴良・重田康成・ Allan Gil S. Fernando ・岡田尚武
Appendices 1–8
Stratigraphy of the Upper Cretaceous System in the Makarov Area 113
Appendix 1. Locality map along the Victoria River (part 1).
114 Haruyoshi Maeda et al.
Appendix 2. Locality map along the Victoria River (part 2).
Stratigraphy of the Upper Cretaceous System in the Makarov Area 115
Appendix 3. Locality map along the Victoria River (part 3).
116 Haruyoshi Maeda et al.
Appendix 4. Locality map along the Victoria River (part 4).
Stratigraphy of the Upper Cretaceous System in the Makarov Area 117
Appendix 5. Locality map along the Rechitsa River.
118 Haruyoshi Maeda et al.
Appendix 6. Locality map along the Acacia River (part 1). 001–021: samples for calcareous nannofossil biostratigraphy.
Stratigraphy of the Upper Cretaceous System in the Makarov Area 119
Appendix 7. Locality map along the Acacia River (part 2). 022–031: samples for calcareous nannofossil biostratigraphy.
120 Haruyoshi Maeda et al.
Appendix 8. Locality map along the Grudzovka River.
... The inner whorls of Gaudryceras hamanakense Matsumoto and Yoshida, 1979 from the Maastrichtian of Hokkaido, Japan and Sakhalin, Russia (Matsumoto and Yoshida 1979;Maeda et al. 2005) are similar to G. submurdochi sp. nov., but the former has finer ribs that continue into the body chamber. ...
... However, they are narrower and less flexuous, and have a more compressed whorl section (Wb/Wh ~0.65). Similar flattened but wider ribs are observed on the last whorl of A. matsumotoi Morozumi, 1985, from the upper Maastrichtian (Maeda et al. 2005;Shigeta and Nishimura 2014). The Maastrichtian Anagaudryceras lueneburgense (Schlüter, 1872) has dense flexuous ribs accompanied by constriction at the adult body chamber, but these are less broad than in A. calabozoi Raffi and Olivero sp. ...
... In addition, A. tennenti has five collars per whorl in the adult stage and is more depressed (Wb/Wh ~1.10, D 48 mm). Matsumoto in Matsumoto et al. (1985) described Anagaudryceras nanum from a juvenile specimen (D 24 mm) and Maeda et al. (2005) described new material from Hokkaido but did not give morphological measurements. However, these juveniles specimens with a very evolute shell present sinuous lirae and narrow constrictions followed by flares (or band-like ribs according to Maeda et al. 2005). ...
Article
Full-text available
We describe new material of the subfamily Gaudryceratinae in Antarctica, including five new species: Gaudryceras submurdochi Raffi and Olivero sp. nov., Anagaudryceras calabozoi Raffi and Olivero sp. nov., Anagaudryceras subcompressum Raffi and Olivero sp. nov., Anagaudryceras sanctuarium Raffi and Olivero sp. nov., and Zelandites pujatoi Raffi and Olivero sp. nov., recorded in Santonian to Maastrichtian deposits of the James Ross Basin. The early to mid-Campanian A. calabozoi Raffi and Olivero sp. nov. exhibits a clear dimorphism, expressed by marked differences in the ornament of the adult body chamber. Contrary to the scarcity of representative members of the subfamily Gaudryceratinae in the Upper Cretaceous of other localities in the Southern Hemisphere, the Antarctic record reveals high abundance and diversity of 15 species and three genera in total. This highly diversified record of gaudryceratins is only comparable with the Santonian–Maastrichtian Gaudryceratinae of Hokkaido, Japan and Sakhalin, Russia, which yields a large number of species of Anagaudryceras, Gaudryceras, and Zelandites. The reasons for a similar, highly diversified record of the Gaudryceratinae in these distant and geographically nearly antipodal regions are not clear, but we argue that they probably reflect a similar paleoecological control.
... The genus ranges from Aptian to Maastrichtian strata worldwide (e.g., Hoffmann 2015). Five species of Tetragonites are known from the Yezo Group cropping out in Hokkaido, northern Japan and Sakhalin, Russian Far East (Jimbo 1894;Yabe 1903;Matsumoto 1942;Shigeta 1989;Matsumoto and Toshimitsu 1991;Maeda et al. 2005). One remarkable species among them, Tetragonites minimus Shigeta, 1989, having small-sized shell with adorally convex aperture on the venter was established by Shigeta (1989). ...
Article
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Mature modifications, ontogeny, and dimorphism of the small-sized tetragonitid ammonoid Tetragonites minimus were investigated in 43 specimens from the Santonian, Upper Cretaceous of the northwestern area of Hokkaido, Japan. Four types of mature modifications were recognised in the shell diameters of 11–13 mm and 16–19 mm, and two differently sized adults were regarded as microconchs and macroconchs respectively. The conch forms of dimorphic pairs were similar in juvenile but differ in the later stage. The supplementary analysis showed that the remarkable adult size differences in antidimorphs continued at least in the Turonian–Santonian. The mature size and size differ�ence between dimorphic pairs decreased chronologically. 36 specimens (84% of examined specimens) were mature, and immature shells were rare in the Santonian. Most of the shells were remarkably well preserved, indicating that T. minimus assemblage fossilised quickly near their original habitat without long-distance post-mortem transport. Hence the bias in the fossil occurrence of adult T. minimus is unlikely to be due to taphonomy such as the bias of fossilisation potential and floatability in the bottom currents. Tetragonites minimus might have been changing their habitats during their life cycle.
... Tetragonites popetensis Yabe, 1903 are widely distributed in the Upper Cretaceous successions in this particular region (e.g. Shigeta, 1989;Maeda et al., 2005). As Shigeta et al. (2016) earlier pointed out, the resultant late middle Campanian ammonoid faunas of the Northwest Pacific region may have been supplemented by the addition of "foreign (or immigrant) taxa" that migrated from other regions into the existing indigenous ammonoid population. ...
Article
The discovery of the heteromorph ammonoid Amapondella amapondense (van Hoepen) in the lower middle Campanian in the Urakawa, Biratori and Hidaka areas of Hokkaido, northern Japan, represents the first report of this taxon in the Northwest Pacific region. Because the species flourished in other regions during Santonian to early Campanian time, its final geographic occurrence in Hokkaido suggests that global environmental changes likely had a significant influence on ammonoid biogeography during early middle Campanian time.