Bulletin of the Geological Survey of Japan,vo1.49(12),p.621-631,1998
On some躍ec童es of Sh醜膿擁eεms(Ammonoi磁ea)from塩e Cre晦eeo鵬o登翌ok:ka畳磁o,No臆hぬ:pan
(Studies of the Cretaceous ammonites from Ho:kkaido and Sakhalin-LXXXIV)
Tatsuro MATsuMoTo*and Seiichi TosHIMITsu**
Tatsuro MATsuMoTo and Seiichi TosHIMITsu(1998)On some species of Sh召脚σo醐ε(Ammonoidea)
from the Cretaceous of Hokkaido,North Japan(Stu(iies of the Cretaceous ammonites from Hokkaido
and Sakhalin-LXXXIV).B%IJ.Gεol.S%γ∂.ノ吻α%,voL49(12),p.621-631,2figs.,2tables.,3plates.
Abst聡ct:Two ammonite species,Sh召ゆ6吻名8sガo名魏6α6Spath and Shαゆ6吻昭s郷ooα彫6勿%6ηs6
(Choffat)are(iescribed as the first records of their occurrences in the Cretaceous of Hokkaido.
The former,which has been known as fairly widespread,is now exten(1e(i its distribution further
to Hokkaido of the North Pacific region and can be called a cosmoplitan in the early Cenoman-
ian time.Sh卿6初郷窺oo翻6蜘6刀s6,which was solely recorded from Mozambique,is now recog-
nized to occur in the Lower Cenomanian of much distant Hokkaido.Further investigations wou1(1
improve our knowledge on the taxonomy and distribution of various species of Shαゆ6魏名αs so
that they would become good indices of the Lower Cenomanian for the global correlation.
1.亙ntroduct量on
The Cretaceous ammonite gems S肋ゆ痂6撚includes
several species which occur in much separated areas
of the world,whereas a few others of the same genus
have been recor(1ed from a limited place.Shαゆ厩6盟s
た伽α6Matsumoto and Kawashita,1995is,so far,an
example of the latter case,whereas S.別翻6α翻窺
(B6se,1928)is that of the former case,since it has
been recently foun(1from Japan in addition to its oc-
currences in Mexico,Texas and Angola(Matsumoto くじ
and Kawashita,1998).Whether the recor(1from an
isolated place implies really an endemic(iistribution
or is merely due to insufficient investigation is a
problem to be clarified.
In this paper we describe a(1ditional two Shαゆ6初燃
species from Hokkaido which may be concemedwith the above problem of distribution.
The repositories of the specimens described below
are as fo110ws,with the abbreviation of the institu-
tion at the heading:
GK: Department of Geology(so-called previ-
ously,but now change(i to the Department
of Earth and Planetary Sciences),Faculty
of Science,Kyushu University,Fukuoka,
812-8581
GSJ: Geological Museum,Geological Survey of Japan,Tsukluba,305-8567
YCM:Yokosuka City.Museum,95Fukada-dai, Yokosuka,238-0016
Details of the geographic and stratigraphic setting
of the describe(1a㎜onites are described in the pre-
viously published papers,which are to be indicated
in the items of〃i薦吻l and O66π耀no6in the palae-
ontological descriptions.To supplement them Fig-
ures l and2are shown in this paper.
2.Palaeontolo9量caldescri夢tions
Class Cephalopoda
Order Ammonoidea
Subor(ier Ammonitina
Family Acanthoceratidae Grossouv:re,1894
Subfamily Mantelliceratinae Hyatt,1903 Genus Shαゆ6」66昭s Hyatt,1903
現)6砂66づ(gs.一/1盟zηzo%露6s彪あo乙召zノ勿s Sharpe,1855
(P.31,P1.14,fig.1)by original designation of Hyatt
(1903,P.111).
R6解α娩s.一For the generic diagnosis and the gen-
eral accounts of Shα勿6廊6郷readers may refer to
Wright and Kemedy(1984,p.126)and Wright(1996,P.154).
*c/o Department of Ear仕しand Planetary Sciences,Fac-
ulty of Science,Kyushu University,Fukuoka,812-8581
Japan**GeologicaI Museum,GSJ
Keywords:Cenomanian,Cretaceous,correlation,distribu-tion,Hokkaido,North Japan,Shσゆ6づ06郷,Ammonoidea
一621一
Bz61」2劾z(ゾ渉h¢GεoJo9宛αl Sz47∂εlyげノ吻)α%,1Vol.49,〈b.ヱ2,ヱ998
○
44。N
42。N
A.
・1㊥二・
璽)0・
θ
Y ロ ’薗,一
● 齢 ,
も も
M’
0 50km142。E
Fig.1Map of the main part of Hokkaido,indicating the
outcropping areas of the post-Aptian Cretaceous by dots.
Three areas where described.Shα勿6」66履s specimens were
collected:A:Ashibetsu(Hachigatsu-zawa),M:Mon-betsu(Chennai・zawa),Y l Yubari Mts.(River Shirakin).
S肋η)6あ6名αs/Zoz6nαz6Spath,1925
(Plate l)
助ηo剛脚。一
且6催孟ho66名鷹1αあ61σ加κ窺(Sharpe)l Douvill6,1904,p.
239,pl.31,fig.3.
Sh6z厚)6ズ66名鷹ノ:Zo76%6召6Spath,1925,P.198,P1.371Co1-
1ignon,1933,p.67,p1.6,fig.51Matsumoto,1959,p.
69,fig.281Howarth,1985,p.86,figs.15-19.
Shσゆ6初昭sgol磁h Haas,1942,p.7,fig.7.
?丁励πα121066郷吻h%α1づlo6%s6Kellum and Mintz,
1962,p.276,pl.6,fig.11p1.7,figs.1,21p1.8,fig.1.
Shαゆ8乞6θz硲sohh6ε陀7づHyatt l Collignon,1964,P.102,
p1.353,fig.1564.
Sh(zηう6乞6(ヲ名αs ∂oh勿)α187zsε Collignon, 1964, P. 104, P1.
354,fig.1565.
Shαη)6勿6名薦 oo6乞46π如躊 Benavi(ies-Caceres, Renz,
1982,p.68,p1.21,fig.1;text-fig.48.
劾loゆ6.一 The specimen from Maputoland,southeastem coastal area of Mozambique,describedand illustrated by Spath(1925,P.198,P1.37(by origi-
na1(iesignation in the explanation of p1.37).
〃iα云67宛乙一GK.H8499(Plate1),collected by Toshio
Shimamki and Yoshitaro Kawashita on Apri115,1997 from a boulder of the rivulet calle(i Chennai-
zawa,a tributary of the River Monbetsu,southem
central Hokkaido (Fig.1).One of the plaster casts
prepared by Toshimitsu is kept at GSJ(F l5199)and
others were sent to the persons who donated the
specimen to GK.
Z)6s6吻!ズo%.一The specimen is wholly septate and
about170mm in diameter.Its hreserved end is pre-
sumably at or near the last septum.The outer whorl
is fairly well preserved on the right side,but its left
side is distorted and shows only a part of the whorl
flank and the depresse(i ornament.
The outer whorl expands with a low ratio,encir-
cling the umbilicus of moderate width(U/D=0.34).
The umbilical wall is low but nearly vertical to the
plane of coiling.The whorl is subrectangular in a re-
stored cross section.It is parallel sided an(i slightly
higher than broad(in the intercostal part)or nearly
as high as broa(i across the costal part.
The outer whorl is omamented by rectiradiate
simple ribs,which become distant with growth.
Each rib has nearly e(luidistant three tubercles on
the flank,the bullate one at the umbilical end,rather
rounded or elliptical one at the mid-flank and larger
imer ventrolateral one.In addition to them there is
a clavate outer ventral tubercle.Although the two
ventrolateral tubercles are close to each other,they
are not united into a large protuberance.The inner
ventrolateral tubercle has a thick dome like elevation
at its base an(l is stretched laterally ra仕しer廿lan uf)ward,
forming a short hom.
Sutures are exposed here and the女e,following the
general pattern of the genus.
D枷6%sズo%.一See Table1.
Co彫勿7まso%.一This specimen shows the characters
that conform well those of the holotype and other
typical examples of Shα勿6魏郷刀oz6%6磁Spath.It is,
hence,identified with this species,although its mode
of preservation is somewhat incomplete.In the early
part of the outer whorl and the preceding portion of
the inner whorl of the holotype,ribs are mostly simple
as those of the adult stage,but they are more crowded
in earlier stages.The same feature is observable in
the specimen from Hokkaido,although the ribs on
the younger part are sho㎜rather indis丘nctly on account
of poor preservation.
Z)客s6z5ss乞oη.一The holotype of this species is probably
一622一
Shごzゆ6づ66名αsノテo%z∬o々彦8づ40(皿ごz云sz6郷o渉06zgz4710shづ〃z露s%ブ
Table l Measurements of Sh卯6初燃ガo紹ηo召6Spath.
Specimen D U Uの H H圧) B B圧) B涯{ H丑1 R
GK。H8499(E,ic)
Holotype(E,c)
〃 (LS,ic)
Howarth,fig.17
~170
220
~165
195
58
69
56
56
.34
.31
.34
.29
58
86
63
78
.34
.39
.38
.40
~52
54
58
.31
.33
.30
.90
.86
.74
1.32
1.37
1.32
9913
11
D=diameter,U=width ofumbilicus,H=whorレheight,B=whor1.breadth,h=whorl.height
at halfa whorl adapically from H,R=number ofribs perhalfa whorl,~=approximatel
Eニnear the preserved end,c=costa1,ic=intercostal,LS=at omearthe last septum;
Howarth,fig.17=H:owarth,1985,fig.17.Linear dimension inmm.
adult,but only an adapical part of the body chamber
is preserved,as shown by the illustration of Spath
(1925,p1.37).Originally it may have exceeded280mm
in diameter,provided that the body chamber occupied
at least half a whor1.
We agree with Howarth(1985,p.88)in regarding
Sh召ゆ6づ66郷801磁hHaas(1942,p。7,fig.7),from Angola,
as a synonym of S.刀076%6召6.It exceeds300mm in
size and may exemplify a completely preserved adult
example,as Howarth has interpreted.
Shαゆ6乞6召z偽oco乞4ε蛎α1丞Benavides-Caceres of Renz
(1982,p.68,pL21,fig。11text-fig.48),from Venezuela,
is probably a synonym of S.刀o名2%o磁,as Howarth(1985)
has pointed out,although Renz7s(1982)illustration
was only for the inner whorl detached from a large
but incomplete outer whor1.Likewise,a large holotype
(368mm diameter)of TZ4h襯121006郷オ1αh鷹1乞lo6%s6
Kellum and Mintz(1962,p.276,p1.6,fig.11pl.7,
figs.1,2),from the Indidura Formation of Coahuila,
Mexico,is very close to S.刀o耀惚,as Matsumoto
6齢よ(1969,p.260)mentioned.Its compressed whorl
is certainly due to secqndary deformation.
The holotype of S.oo6毎6%如16Benavides-Caceres,
1956(p.465,p1.54,figs.5,6),from Peru,is probably
referable to S.s6hh昭彪万 Hyatt,1903,0n the ground
of the disposition of moderately coarse ribs which
are separated by interspaces slightly wider than the
ribs.In this respect we would agree with Wright and
Kemedy(1987,p.129)to regard it as a synonym of S。
s6hl鷹云副Hyatt,1903.However,the umbilical ratio
of S.060乞4伽妬6(U/D=0.33)is considerably lower
than that of the lectotype of S.s6hl膨ホ6万(U/D=0.40)
estimated from the figure of Sch1盤ter(1871,p1.7,figs.
4,5).This may be due to a change with growth,for
that lectotype is very large(about350mm diameter).
In fact,from the illustration of the French specimen
(Wright and Kennedy,1987,text-fig.33」)U/D is es-
timated as O.33at D(ic)=135mm(the same size as
Benavides-Caceres specimen)and.0.38at D(ic)=175
mm at the preserved end of the still septate specimen.
On the other hand S.sohlz昭彪7!J of CoIlignon(1964,
p.102,p1.353,:fig.1564)is certainly S.〆Zozのzoσ6be-
cause of the configuration of its omament and the
umbilical ratio(0.33).The holotype of S.∂oh勿α16多zs8
Collignon (1964,P.104,P1.354,fig. 1565),another
specimen from Madagascar,is undoubtedly identified
with S.刀o名召ηo磁.Its umbilical ratio estimated from
the figure is O.32at the intercostal diameter145mm
This specimen is similar to the holotype of S.πo彫%6召6
in size and also in showing the adult type distant ribs
with strong imer ventrolateral tubercles on its pre-
served last quater whorl.The size of its full grown
original shell is,however,hardly estimate(i because
the position of its last septum is not clearly indicated
on the figure.At any rate,whether S.刀o名6%6召6was
dimorphic or not is hardly decided from the available
material in spite of the situation that the specimens
referable to this species are comparatively numerous
and that some of them are very large(368mm).In
other words,no example of undoubted microconch
has been confirmed.
Although several specimens from England were re-
ferre(1to S.プZoアのzoαεby Klenne(ly(1971,P.67,pl.25,
fig。2),we hesitate to approve the occurrence of this
species there.At least one of them(oρ.碗.,pL25,fig.
2)has been altered to Shα膨ズ06撚sp.by Wright and
Kennedy(1987,p.129,pL41,fig.21text-fig.34B),
because S.πo紹郷α6at the yomg stage as small as
that specimen has more crowded and less stout ribs
and probably more compressed whor1.That specimen
rather resembles the young shell of S.soh伽孟痂,as
represented by the imer whorl of the we11-preserved
example figuredbyKaplan6砿(1984,p1.2,fig.1).We
are at present unable to give remarks on the affinities
of this and certain other specimens,including S.
ho錫go Matsumoto,Muramoto and Takahashi(1969,
p.261,pL 29,fig,11 pL 30,fig,エl text-figs。3,4)
from Hokkaid.o,with Shαゆε魏z偽ヵlloあ(Collignon,
1931,p.81,p1.8,figs.9-12).The problem is,however,
important for getting more reliable knowledge on
taxonomy and distribution of the species concerned.
We are,hence,anxious to look at relevant specimens
一623一
B%Jl6蕗7z(ゾ孟h6Gεolo9∫oαJ Sz67∂εly(ゾノ4φα%,▽101.49,ハb.ヱ2,ヱ998
of successive growth stages from oversea regions.
Ooo鋸解%66.一The sole example of this species from
Hokkaido is from the lower Cenomanian mudstonealong the Chemai-zawa,a small branch rivulet of the
River MonbetsuatHirotomi.Theareaisinthegeologicalsheet map of“Biu”(Yoshida6彪乙,1959),but the locality
was not indicated in that map.The Upper Cretaceous
of the area was subsequently sub(1ivide(1into the
Members A1,A2to D by Akitoshi Inoma(personal
communication to T.M.),as shownby Matsumoto6砿
(1997,fig.1).Theunit ofmudstone alongtheChemai-
zawa istheMemberA1,whichhasyielded,inadditiontothis speciesうShごzη)6廊醐鷹窺ε%乞o召%π彫(Bδse),D6s窺066郷
(Psεz6ゴoz6hl歪921」α)ブの)oアz乞6z6甥Yabe,Gα6配ooε劣偽』yε90ε多zs(3
Shigeta and Pα吻。側667オ611α肋磁花吻襯Matsumoto.
The&ssemb1&ge indicates the e&rly Cenomanian age.
Outside Japan,S.プ70名ozαz6 haε been-reported to
occur in Mozambique,Madagascar,Angola,Vene-zuela,Mexico,Texas and Ira耳.Thus,it is distrib-
uted worldwide,although the studie(i specimens in
respective regions are not numerous(see references
in the synonymy list).
Sh卿6づ6獺s彫oo翻6蜘6%s6(Choffat,1903) (Plates2,3)
Synonymy.一/1αzn孟ho66名とzs如あo乙σzノづz御z(Sharpe)var.盟zo6α解扉(~z66%s乞s
Choffat,1903,P.25,P1.4,fig.3a,b an(1P1.7,fig.1a,b.
Shσゆ(3づ66名薦aff.S.乙6zガo乙ごzz7づz6〃z var.わz4ぢ6召Kossmat l
Shimizuαごzl.,1953,P.14(1isted only).
S加吻魏郷aff.S.∂oh吻伽s¢Collignonl Matsumoto and Suekane,1987,p.3,p1.1,figs.1-3.
刀∂♂o顔6.一A single specimen from Conducia,
northeastem coastal area of Mozambique,describedand illustrated as/16α多z云hoα3名とzs l6zガoJごzz疹%盟z (Sharpe)
var.ηzoαz錫zわ勿z紹%s丞 Choffat (1903, z疹46 szφ名召) (by
monotypy).
〃1伽吻1.一The following two specimens from
Hokkaido:(1)GSJ F5151,collected by K.Tanakain l951at Locality52,0n a branch rivulet in the upper
reaches of the Hachigatsu-zawa,a tributary ofthe River
Ashibetsu,from thelower part ofthe Mikasa Fomlation
(see Shimizuαごz乙,1953,route map2an(i also geological
sheet map of Kamiashibetsu forthelocation).According
to the subsequent work by Matsumoto and Okada(1973,P.289,figs.9,10),its precise horizon is referred
to the basal part of the middle member(marked as
Mkm)oftheMikasaFomation(seeFig.20f面spaper).(2)YCM、713,collected by T.Suekane at loc.S9010n
the left side of the River Shirakin[=Hakkin-zawa
by some authors]in the Yubari Mountains(Fig.11
see Matsumoto and Suekane,1987,text.fig.1,for the
locality and pL1,figs.1-3for the much reduced i1-
Iustration of this specimen).The plaster cast of this
specimen is GK.H9647.
Z)6so吻渉20%.一The two specimens are similarly large.
At about the last septum the intercostal diameter of
YCM.713is265mm.The body chamber of YCM.713is incompletely preserved l namely its ventral half
and its last portion are destroyed away.On the as-
sumption that its body chamber was half a whor1,as
My
\
¥
¥
!35
/
’1㊥Loc・52
1
\
¥
\4・\45
Mkm
訟45
/
1\
\
、 ¥
\Mkl¥ ¥
覧
¥
\
¥
0
1\42
¥
、
Mku
42。25730FF
4\35
300m142。5’
Fig.2 Geological route map of the・Hachigatsu-zawa(part),indicating Loc.52.Chain:Boundary of
lithostratigrahic mits.My:Main part of the Middle Yezo Subgroup。Mk1,Mkm,Mku:Lower,Middle
and Upper Members of the Mikasa Formation.Broken line:fault.(Adapted from Matsumoto andOkada,1973,fig.9).
一624一
Sh(zゆ召廊επzsノテo粥πo為たα♂40佛α孟sz4ηzo渉o(z多z4Tosh♂窺砿s%フ
Table2Measurements of Sh召膨魏郷彫06召解δ吻6ηs6(Choffat)and Sh召卿吻郷s6hJ襯6η’Hyatt(1ectotype)(at the bottom).
Specimen D U UID H H!D B B/D B/H Hlh R
GSJ F5151(E,ic)
〃 (E,c)
YCM.713(E-150。)
Holotype(E-1500)
255
260
265
350
85
83
85
100
.33
.32
.32
.29
104
110
108
132
.41
.42
.41
.38
~70
~78
96
.27
.30
.28
.67
.71
.73
1.58
1.62
1。50
11
12
11
12
S.s6hlμε∫8r∫ 348 135 .39 123 .35 102 .29 .83 1.37 13
E-1500ニat the point1500adaptically from E(preserved end).Other symbols as forTable1.
Measurements of the holotype ofS.〃200α励∫gμ6nsεdepend on Choffat(1903,p。26,pl.4,且g.
3a,bandpL7,丘g,1a,b);those of3。sohl惚67∫arecitedfromWrightandKemedy,1987,p.130.
in other better preserved examples of Sh6z厚)6づ06名召s,
the entire shell di註meter of this specimen would have
been nearly as large as420mm.
GSJ F5151is wholly septate,but its preserved en(1
is presumably at or near the last septum.Its earlier
part of the preserved outer whorl is again incomplete,
but owing to the regular disposition of tubercle,the
outline of the missing Part can be reconstructed.
Thus,the intercostal diameter near the preserved
end(markedMinPlate2)isestimatedas255mmandthecostaldiameterimmediatelybehindMisabout260mm.This size is,thus,quite similar to that
of YCM.713at the last septum.
In both specimens the rate of whorl expansion is
fairly high(H/h:about1.5)and the width of umbilicus
is about one third of the shell diameter.The specimens
may be secondarily compresse(1,but from the less de-
formed part(the left side in YCM.713and the right
side in GSJ F5151)the ratio B/H is estimated as
slightly less than O.7 at the intercostal part an(i
somewhat more than O.7in the costal section.The
whorl section is subrectangular.The flank is very
weakly convex in GSJ F5151and nearly flat in
YCM.713.As the latter specimen was embedded in
mudstone,its original shape may have been secon-
darily flattened.The umbilical ed.ge is abruptly bent
to the steep wa11,which in tum is overhanging and
gently convex rather than strictly flat二
The omament of the outer whorl is characteristic.
It consists of long ribs,which have tubercles in five
rows.The ribs are weakly prorsiradiate with a very
gently concave curvature on the flank of the early
part of the outer whorl and become nearly rectiradiate
in the later part.They are separated by much wider
interspaces and gradually strengthen with growth.
The five tubercles are(1)the bullate umbilical one,
(2)the subromded or elliptical one of moderate in-
tensity at about the middle of flank(somewhat inside
of the strict mid-flahk),(3)the weaker one on the
outer part of flank(midway between the second and
the fourth ones),(4)the larger and stronger one at
the imer ventrolateral shoulder which stretches side-
ways,and(5)the clavate outer ventrolateral one.
The tubercles also strengthen with growth alongwith the ribs,although some of the tubercles appear
to be blunt on accomt of weathering.
The sutures are well exposed on the surface of
YCM.713.They are similar to those of the illustrated
large specimen of S.観づ6伽伽窺(Wfight and Kemedy,
1987,text-fig.30).
Z)珈6%s歪o銘.一See Table2.
Co彫勿7乞so%.一The described two specimens are best
referable to Shごzηり6勿6矧sηzo6召%z房(1z彪ns6(Choffat,1903),
because of their very large size,rather low umbilical
ratio(U/D about O.3),comparatively compressed
whor1(B/H about O。7),simple long ribs disposed at
fairly wide intervals on t血e outer whorl and tubercles in
five rows,of which those on the outer flank are weaker
than others but independent and dispose(1at midway
between the mid-1ateral and imer ventrolateral ones
and those at the ventrolateral shoulder are strong
and stretch sideways.
GSJ F5151was listed as Shαゆ6吻槻s aff.Z誠6伽勉彫
var.初4初Kossmat by Shimizu6短乙(1953,p.14),
but it does pot fit the form described by Kossmat
(1895,P.199,P1.24,figs.5,6),for the latter is smal1
&nd has intercalated or brαnched ribs frequently.
F6rster(1975,p.247,pl.16,fig.5)regarded Kossmat’s
(1895)species as掘α多z云611廊6名os勿z4歪o%窺(Kossmat).
In the previous work of Matsumoto and Suekane
(1987,p.3,p1.1,figs.1-3),the specimen YCM.713
was described under Shαゆ6吻鵤s aff.S.∂ohゆ認6ηs6
Collignon.This was misleading.They(1id not notice
the outer lateral tubercles,which are weak but shown
on the photograph.As has been mentioned already~S。
∂oh勿ごzl6%s6 is a synonym of S.プZoz即zαz6 Spath (see
also discussion below).
.ρゑs6鋸ss加..一S.郷oo召励名卿鷹isalliedtoS.刀o欄鷹
in that the two species commonly show a fairly narrow
umbilical ratio(U/D around O.3),that the ribs become
increasingly distant and strong with growth whereby
the inner ventrolateral tubercles stretch si(lew=ays in
一625一
βz6116訪z(ゾオh6G60109乞αzl Sz67%yの‘ノめり磁z,▽lol.49,2Vo.12,ヱ998
a style of homs.The two species,however,can be
distinguished l namely in S.πo紹%6磁the ribs are
more crowded in earlier part and become separated
more rapidly later.Although there may be some extent
of variation,S.ノZo名6%6α6has generally broader whorls
with a larger ratio of B/H and also coaser and more
robust ribs in comparison with S.卿ooα郷6勿%6%s6.
The existence of the outer lateral tubercles at midway
between the mi(1-1ateral and the imer ventrolateral
tubercles throughout the outer full whorl is charac-
teristic of S.盟zoαz盟z擁(~z6卯zs6,although they are not
strong。
Wright andKemedy(1987,p.129)1isted、46翻ho66燃乙6z渉勿1αz7伽ηz var.ηzoαzηz扉(7z6ωzs釣Choffat,1903[publi曲e(i
in January]as a synonym of Sh4ゆ6初解s s6hl%吻7乞
Hyatt,1903[published in May or later],though with
a query.In our opinion the two species can be distin-
guished.Namely,S.解06α窺吻%6%sεkeeps to have a
comparatively narrow umbilicus even in the lategrowth stage,showing U/D about O.3in contrast to
about O.40f S.s6h伽彪nl The ribs become more distant
with growth in the former than in the latter.As a result
the ribs on the large outer whorl are less numerous
in S.盟zooα盟z6勾z6のzs6than in S.s6hh6(払674for instance
220r23in the former compared with280r29in thelatter.This difference would be more pronounced on
the adult body chamber of about half a whor1,a1-
though completely preserved examples are not avai1-
able at present。
Accordingto W士ightandKemedy(1987,p.130),there
are some British examples of S.sohl膨診副in which
an outer lateral Ulbercle apPears at dianleters of290㎜.
Without seeing the specimens or good illustrations,
we hesitate to give adequate remarks on this infor-
mation.We expect,as a possibility,thatthose British
specimens could be referable to Shσゆ厩6鰯h貌襯6
Matsumoto and Kawashita,1995(see revised descrip-
tion of Matsumoto and Kawashita,1998,p.92,figs.3,
4)。S.庖肋磁indeed resembles S.sohl%漉万in the
large size(D=410mm near the apertural end of the
adult holotype),fairly wide umbilicus(U/D=0.42),
and the coarse ribs on the outer whor1,except for
the finer flange on the apertural margin.However,
the former has a distinctrow of outer lateral tubercles
in contrast to no record of such a character for the
latter in the descriptions of Sch1Uter(!871)a.nd Hyatt
(1903).At any rate,we should make the true state
more clearly by further examination of sufficient
materia1.
Oooκ%%66.一See material for the geographical
locations ofthe twosp㏄im㎝sfrom Hokkaido.GSJ F5151
came from the lower part of the Mikasa Formation.
It was in the sandy siltstone(or silty fine-grained
sandstone)atthehorizonabout130mabovethebaseof the Mikasa Formation.P6s彫oo6燃(A6雇o%hl忽61勿
ノのo%加吻occurs from this and other levels(above an(1
below)showing a long range through the Cenomanian.
Ando(1990)suggested that the basal part of the Mikasa
Formation along this route is referable to the Upper
Albianontheevidenceofa㎜o撮tewbchistenta廿velycalled Cαη励塵飽s aff.s励sズ吻忽Spath(Matsumoto
α磁,1991).YCM.713is withintheunit ofthe mudstone
expose(1along the upPer course of the River Shirakin.
It is associated with a species allied to肋oo6昭窺鷹(s.1.)
o吻卿Mantell and its horizon is reasonably below
the horizon of C観%初g云on乞66郷如hαh4s鰭(Matsumoto),
a middle Cenomanian ammonite.Because of a folde(1
stmcture what comes below the horizon of YCM.713
is not known.At any rate,the described two speci-
mens came from somewhere in the lower part of the
Cenomanian. The age of the holotype of S.窺ooα卿6勾%6%s6is not
precisely recorded.Undoubted examples of the same
species have not been reported from other regions.
As Hokkaido,northem Japan,is much separatedfrom Mozambique,the species can be expectedto occur
widely in other regions of the wor1(1.
3. S盟m灘ma買y o≦!置es題亘ts
In this paper two ammonoi(1species,Shσゆ砒6z薦
〆Zoz6多z6α6Spath,1925and Shごzηり6づ66名召s〃zo6α%z扉(7z昭%s6
(Choffat,1903)are described on the specimens from the
Lower Cenomanian of Hokkaido.The former is based
on a recent acquisition fromthe Monbetsu area,south-
central Hokkaido,whereas the latter(1epends on the
two specimens previously reported under different
names,one from the Ashibetsu area and the other
from the Yubari Mountains of central Hokkaido.
S.刀o形η6α6is known to distribute worldwide,a1-
though some specimens have been reported under
several dissimilar names which should be regar(ied
as synonymous with S.刀oz6%oσ6.
S.別ooo:彫δ勿%%s6was previously reported solely
from a locality in northem Mozambique.This paper
gives the first record of its occurrence outside that
area.There is,however,an opinion(Wright andKemedy,1987,p.127)thaガit might be included in
the better known species,S.s6hl%吻万Hyatt,1903.At
present we do not agree with廿亘s view and suggest that
S.観襯6Matsumoto and Kawashita,1995,recentlyestablished on a specimen from Hokkaido,is more
closely allied to,if not identical with,S.s6hlπ碗π.
At any rate,further investigations on sufficient
material are required to make clear the true state.
Species of Shαゆ6初燃would,thus,becomegood indices
of the Lower Cenomanian for the global correlation.
Ack亙琶ow亘e哩geme醜ts:We appreciate the laborious
field works of Dr.Keisaku Tanaka(former staff
member of GSJ),Messrs.Tetsuro Suekane,Yoshitaro
Kawashita and Toshio Shimanuki,who・collected and
supplied the valuable specimens of Shα勿痂6名偽for
this study.Thanks are(1ue to Dr.Yasumitsu Kanie
一626一
Shαゆε乞oεzαsノケoηz五乙oたゐα疹40(7屡ζz6s%ηzo孟o(z多z4Tosh乞窺魔s%ク
for providing a photograph of YCM specimen and
also Dr.Yukio Yanagisawa for careful improvements
of the manuscript.
Re£ere醜lces
Ando,H.(1990)Stratigraphy and shallow marine
sedimentary facies of the Mikasa Formation,
Middle Yezo Group(Upper Cretaceous).力解.
G601.So6.ノの6z%,96,279-295.(in Japanese
with English abstract)
Benavides-Caceres,V.E.(1956)Cretaceous system
玉n northern Peru.βz611.ノ1ηz6飢ノ匠z6s.皿zゑπ廊差,
108,353-494,pls.31-66.
B6se,E。(1928)Cretaceous ammonites from Texas
and northem Mexico.β%ll.0勉∂.7セ%αs,Bπ7.
E60%.G601.T66hηo乙,2748(for1927),143-312,
pls,1-18.
Choffat,P。(1903)Contributions a la connaisance
g6010gique des Collonies portgaises(1フAfrique.
1.La Cr6tacique de Conducia.Co窺解乞ss歪o%
伽S6吻6606010g蜘64πPo吻即1.32P.,9pls.
Collignon,M.(1931)Pa160ntologie de Madagascar,
XXI.La faune du C6nomanien a fossiles pyhteux
du nort de Madagascar.∠4朋.46.P鷹o鋭.,29,
43-104,pls.5-9.
Collignon,M.(1933)Fossiles C6nomaniens d’Ant-
satramahavelona (Province d7Analalava,
Ma(iagascar)./1%%.(劾乙S励.躍伽8s1嫌】㎎
716z%αηごz万z76,3,53-79,pls.5,6.
Collignon,M.(1964)∠4伽伽ヵs吻soα名伽6溶吻鰯
46漁磁飾催64郷窺o競6s2,ll(C6nomanien), 1-152,Pls.318-375.
Douvi116,F.(1904)Pa160ntologie,mollusques fossiles.
動Morgan,」.de,ed.,〃i癬o銘so勧孟物麗㎝ん鷹
3,191-380,pls.25-50.
F6rster,R.(1975)Die geologische Entwicklung
von SUd-Mozambique seit der Unterkreide
und die ammoniten-Fama von Unterkreide und Cenoman.060乙力h地,B12,3-324,pls.1-17.
Haas,0.(1942)Some Upper Cretaceous ammon- ites from Angola。∠4耀7.〃傭.・鋤∂菰,1182,1-24.
Howarth,M.K.(1985)Cenomanian and Turonian
ammonites from the Novo Redondo area, Angola.β鋸ll.β7魔〃初s.餉ム撚劫(弛o乙s8z,
39,73-105.
Hyatt,A.(1903)Pseu(10ceratites of the Cretaceous.
〃’o勉og7.U.S.G601.S躍∂.,44,1-351,pls.1-47.
:Kaplan,U.,Keller,S.and Wiedmam,J.(1984)
Ammoniten-und Inoceramen-Gliedermg des
nor(ideutschen Cenoman. S6h7舜7626h6 467 Ezゴ”客ss6%s6hl乞6hのz κoηzηz乞ss乞o多z, 7, 307-347,
Pls.1-8.
Kellum,L B.and Mintz,L.W.(1962)Cenomanian
ammonites from the Sierra de Tlahualilo,
Coahuila,Mexico.Coπ7.〃1%s.勘♂60砿U%初.
κ乞6h.,13,267-287,pls.1-8.
Kennedy,W.」.(1971)Cenomanian ammonites from southern England.助60.1R砂.P痂ごz60窺.,
8,H33,pls.1-64.
Kossmat,F.(1895)Untersuchmgen Uber die sUdindische Kreideformation.B魏7.P励Oo短.
G60乙0鉱一砺9.07競差,9,97-203,Pls.15-25.
Matsumoto,T.(1959)Upper Cretaceous ammordtes
of California.Part II.躍6彫.Eα6.S6ぎ.κ夕z6shz6
0励..S6飢D,G60乙5勉,%乙1,1-172,Pls.1-41.
Matsumoto,T.and Kawashita,Y.(1995)A new
ammonite species of Shα勿切66郷from the
Oyubari area.メo%7.Eα6.E4%o.Sα9αU痂”。,
42,186-187,p1.5.
Matsumoto,T.and Kawashita,Y.(1998)Two ammonite species of the genus Shαゆ6初燃
from the Cretaceous of Hokkaido.Pとzl607z差.
R6s6απh,2,89-95.
Matsumoto,T.,Muramoto,T.and Takahashi,T. (1969)Selected acanthoceratids from Hokkaido.
κ6万z.Eα6.Soづ.,瓦yz6shz6乙秒zづ∂..S67.1).G601。,
19,251-296,pls.25-38.
Matsumoto,T.,Noda,M.and Maiya,S.(1991)
Towards an integrated ammonoid,inoceramid-
and foraminiferal biostratigraphy of the
Cenomanian and Turonian(Cretaceous)in Hokkai(io.ノリz67.06097.To々yo,100,378-398.
(in Japanese with English abstract)
Matsumoto,T.and Okada H.(1973)Saku For-
mation of the Yezo geosyncline.SoJ.ノ~の孟s.
1)砂ム G601..幻%shκ Un吻.,2,275-309.(in
Japanese with English abstract)
Matsumoto,T.and Suekane,T.(1987)Some acanthoceratid ammonites from the Yubari
Momtains,Hokkaido-Part1.SoJ.Rのム ∬o左osz6た召C才砂ノ匠z6s6z6%z,no。35,1-14,Pls.1-4.
Matsumoto,T.,Yokoi,K.and Kawashita,Y. (1997)Further notes on the ammonoid genus
Pα吻側わ6吻llα.勘160窺.1~6s卿6h,1,188-199.
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deutschen Krei(1e.Pα」ごzεo多z60g名αゆh乞6α,21,1-24,
pls.1-8.
Sharpe,D.(1855)Description of the fossil remains
of Mollusca found in the Chalk of England.
Part2,Cephalopo(ia.勘舵o多zオ09吻)h勿σl So6勿顔,
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/)乙ごz%6z渉o勿ソ7セ%≠6ゾ孟h6G60109乞66zlノ砿64)q〆ノ砿)6zη.
ヱr50000,Kα%zゑ硲hあ6ゑsπ,Geo1.Surv.Japan,
78p.(in Japanese)十21p.(r6sum6in English).
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pls.28-37.
Wright,C.W.(1996)SuborderA㎜onitinaHyatt,
一627一
Bz6116あアz(ゾ云hθ(3!60109ガ6αl Sz67z2砂(~プノψごz珍 Viol.49,ハ入o.ヱ21ヱ998
1889.動Wright,C.W.with CalIomon,J.H.
and Howarth,M.K.丁翅伽o銘動∂6吻6鰯6 」%160螂ology,磁πL,〃’oll麗S6α4.Z~6薦畷∂0乙
4r C㎎如060郷∠4郷〃zoηo歪46α,GeoL Soc.Amer.,
Boulder and University of Kansas,Lawrence,
9-206。
Wright,C.W.and:Kemedy,W.J.(1984)The
Ammonoidea of the Lower Chalk,Part1. ハ40%09飢P痂εo吻9飢Soα,partof137for1983,
1-126,pls.1-40.
Wright,C.W.and Kemedy,W.J.(1987)The
Ammonoi(1ea of the Lower Chalk.Part2.
」40%09先jp痂6傭o野Soo,partofl39for1985, 127-218,pls.41-55.
Yoshida,T。,Matsuno,K.,Satoh,H.and Yamaguchi,
S.(1959)Z助り彪%ζz孟o老y 7セκ!(ゾ差h6 G6010g勿α1
躍の(ゾノ吻)朋.ヱ」5000αB伽Geo1.Surv.Japan,
47p。(in Japanese)十7p.(abstract in English).
Received August25,1998
Accepted October16,1998
北海道白亜系産アンモナイトSharpeicerasの若干種について
(北海道・サハリン産白亜紀アンモナイトの研究一84)
松本達郎・利光誠一
要 旨
アンモナイトのS勉ゆ就θzαsガ07伽oαεSpathとS勉ゆ厩εz偽別oo翻6匂%%sθ(Choffat〉が北海道の
白亜系からも産出することを,はじめて記載した.前者は従来かなり広い分布を示すことが知られてい
たが,北太平洋地域の北海道にも認められ,セノマニアン初期におけるコスモポリタンと言うことがで
きる.後者はモザンビクだけから記録されていたが,今回甚だ遠隔の北海道のセノマニアン下部から産
出が認められた.今後の研究により,この属の諸種の分類と分布がもっと明確になり,セノマニアン下
部の有効な示準種として世界各地の対比にいっそう役立つようになるであろう.
一628一
8ノ~π7伽1‘1〔~7・硲1)’o〃2五10々々αi40‘〃認s〃ア㍑認o召アz4Toshi規i!szO
c
照
A
鐵畷.
鑛、
畷難難鐸
D
Plate1 Shαηりcガ(}(~ηzs.〃(〃で躍cαピSpath.
GK.H8499,collected by T。Shimalluki and Y.Kawashita from the Chemai-zawa,Mollbetsu area.
A:rightside;B:venter;C:1atepartofventer;D:leftside.Scalebar二3cm. (photo by S.T.without whitenillg)
629
B~4セだηげ!12εG8010g乞ごα!S2〃∂のンqん勉/)‘脚,レbl.49,ノ〉o.12,1998
納弘
、難
欝、・
A
Plate2 Sh召厚)6廊6ηzs n’zo66〃ηわi(1π6ηs召(Choffat).
GSJ F5151,collected by K.Tanaka from loc.520f Hach1gatsu-zawa,Kamiashibetsu area.A:natural frontal section;B:right side.M:positioll of measuremellt of diameter.Scale bar=3cm.
(photo by S.T.without whitening)
一630
Shαゆ顔-6耀s∫〉η〃z」厚ohた厩40‘〃1観s多〃刀o!oαn4Toslz乞解πsz∂
澱簸3
霧、
灘蟹
難灘
1騰綴萎
撚 鐵 z蟹
霧、,鰍渥.
驚廃霧 萎、
汚、霧r雍
馨
灘難、 垂.舅難 雛 鵠
麗灘鞭 嫌 撚霧、 、繊
睡蕪. 麟.
蘇
辮5雛、
灘繍・
聾、難蓬
,鞭難饗鐘灘
.鰯縫態
灘駿,,騰騒
馨織薦
獅拓’
.墾
纂 簿 毎蔀 籔匿 、鱗 灘 嚢 繊購 雛 垂、
醗騒欝 麟籔 購 羅難、描 欝繍,響、鰯、轟
萎議麟懸騰.懸購,, 鶴艶’ 轟灘 難鞭講 難難彗曽詫灘.騨
難・懸. 、綴雛 灘
が 「、,. 蟹叢…翻鰭
・、壁ll
1)late3 Shごzノプ)6i66箔とzsη70αz1麗わ!(1κ8㌶s6(Choffat).
YCM.713,collected by T.Suekane from loc.S9010n the left bank of the River Shirakin,Oyubari
area.Left side.Scale bar二3cm.
(photo by courtesy of Y.Kanie)
一631一