Issue Date 2010-09-00
184 8501 4 1 1
2010 5 21
KOARAI, K. and MATSUKAWA, M.: Nonmarine bivalve community and
paleoecology in the Sanchu Cretaceous, the Outer Zone of
southwest Japan. Bull. Tokyo Gakugei Univ. Div. Nat. Sci., : 103
118. (2010) ISSN 1880 4330
Rich, nonmarine bivalve faunas have been reported from the Sanchu
Cretaceous in Japan. They consist of species found commonly
in Lower Cretaceous strata of the Outer Zone of southwest Japan.
Seventeen species of bivalves are recognized in the faunas of
the
Sanchu Cretaceous. Based on function-morphological analysis and
comparison with living bivalve ecology, the life habits of
these
taxa, as represented by burrowing speed and burrowing depth, are
estimated. Two assemblages of bivalves, the Costocyrena
otsukai
assemblage and the Costocyrena radiatostriata – Tetoria (P.)
sanchuensis assemblage, are recognized in the Shiroi and
Sebayashi
formations, respectively. In particular, the infaunal
shallow-burrower C. otsukai and the infaunal deep-burrower T. (P.)
sanchuensis
co-occur in outcrops of the Sanchu Cretaceous and are interpreted
to have co-existed in the same environments, with each utilizing
a
different depth distribution in the sediment. Similarly, the
infaunal shallow-burrower C. radiatostriata and the infaunal
deep-burrower
T. (P.) sanchuensis also co-existed at the same localities, but
utilized different depth distributions in the sediment column.
This
evidence suggests that these bivalve taxa shared
sediment-distribution space vertically, although both assemblages
represent different
geological ages. This relationship is also similar to that of the
co-occurring infaunal shallow-burrower Myrene (M.)
tetoriensis
and infaunal deep-burrower Tetoria (T.) yokoyamai in the
Jurassic-Cretaceous Tetori Group, of the Inner Zone of southwest
Japan.
Consequently, nonmarine bivalves shared environmental space
vertically, even though of different localities and geological
ages.
Sanchu Cretaceous, nonmarine bivalves, ecology, community
Department of Environmental Science, Tokyo Gakugei University,
4-1-1 Nukuikita-machi, Koganei-shi, Tokyo 184-8501, Japan
Stanley Kondo Isognomon sanchuensisCostocyrena otsukaiC.
radiatostriata — Tetoria (P.) sanchuensis
C. otsukai — T. (P.) sanchuensisC. radiatostriata — T. (P.)
sanchuensis 3
: 103 1182010.
103
Yabe et al., 1926; Hayami, 1958, 1965, 1966; Ohta, 1982; Tamura,
1977, 1979 Matsukawa and Ido, 1993
1995 1998 1999 2003“ ” corbiculoids “”
corbiculoids
Fig. 1. Index map of the Sanchu Cretaceous.
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Yabe et al., 1926; Hayami, 1965, 1966 Matsukawa, 1983
Fig. 1 1977, 1979; Matsukawa, 1983; 2009Fig. 2
Hauterivian BarremianBarremianAptian 2009Hauterivian
Barremian Hauterivian BarremianAptian Barremian 2009 Matsukawa 1983
1995 4 3 Ito and Matsukawa, 1997 8 7 15 Fig. 3, Table 1210A EA
Isognomon sanchuensisB E Hayamina matsukawai, Tetoria
(Paracorbicula)
sanchuensis, Costocyrena radiatostriata Panopea (Myopsis) plicataB,
Ostreidae
gen. et sp. indet. BCArcticidae gen. et sp.
indet. DIto and Matsukawa 1997 AE Isognomon
sanchuensisPanopea
(Myopsis) plicata Ostreidae gen. et sp. indet.A E Figs. 4 and
5
Infauna Epifauna 1996
Fig. 2. Generalized columnar section of the Sanchu Cretaceous with
the location of nonmarine moluscan fossils (Cited from Matsukawa
and Tomishima, 2009).
:
105
Table 1. List of nonmarine molluscan fossils from the Shiroi and
Sebayashi formations, the Sanchu Cretcaeous.
Fig. 3. Map showing the nonmarine molluscan fossil localities. The
prefix SA of the locality number is omitted. The Shiroi Formation:
001, 003, 004, 005, 007, 012, 013,015 in A, and the Sebayashi
Formation : 210, 295, 103 in B.
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Stanley, 1970Stanley1970 HWH/WL H L/HH/
WL/HH/W L/WL/HH/
WL/HH/W L/HH/W L/H H/W Stanley, 1970Rapid Non–rapidStanley1970
B.R.I.Burrowing Rate Index0.6 Rapid burrower Non–rapid burrower
Fig. 6 Stanley1970
Fig. 4. Stratigraphic occurrence of molluscan species and their
individual numbers from the Sebayashi Formation at loc. 210,
Sebayashi, the Sanchu Cretaceous.
Fig. 5. Outcrops bearing molluscan fossils at loc. 210, Sebayashi,
the Sanchu Cretaceous. A-E show levels of occurrence.
:
Stanley1970 3 Kondo1987 SLPallial
Sinus Index ; P.S.I. Fig. 6P.S.I.S L P.S.I.
P.S.I. L L P.S.I. P.S.I. 6 95 Rhoads and Young1970
Fig. 6. Relation between pallial sinus index and maximum relative
burrowing length of six species of nonmarine mollusks from the
Sanchu Cretaceous based on Kondo (1987) (above), and measurement of
pallial sinus length (below).
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Matsukawa and Ido1993 75% 65% Type 75% 65%Type
Type Type Tetoria (T.)
yokoyamai Type TetoriaT. (P.) sanchuensis
T. (T.) yokoyamai active burrower H. naumanni H.
matsukawaiIsodomella
shiroiensisCostocyrena otsukaiC. radiatostriata active
burrower
6 Hayamina matsukawai Stanley1970 Figs. 7 and 8 1L 5 3 1 2 H.
naumanniH. matsukawai C. otsukaiC. radiatostriataI. shiroiensisT.
(P.)
sanchuensisL
Fig. 7. Relation of burrowing rate to gross shell shape and shell
ornamentation of seven species of nonmarine mollusks from the
Sanchu Cretaceous based on Stanley (1970)(above), and burrowing
rate index (below).
:
109
Matsukawa and Ido1993 3 Morishita1959δ 0δ1δ0
δ= 1 Table 2 δ Table 3 3 Fig. 9 2 2 2 2 2 2
Fig. 8. Maximum burrowing depth and burrowing rate of six species
of nonmarine mollusks from the Sanchu Cretaceous.
Table 2. Abundance of individual taxa in 17 containing bivalves
from the Shiroi and Sebayashi formations, the Sanchu Cretaceous.
Numbers in the table show individual numbers.
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Hayamina naumanniTetoria (P.) sanchuensisHayamina
matsukawaiT. (P.) sanchuensisC. radiatostriata 3 15 Isognomon
sanchuensis 3 1 Isognomon sanchuensis 1
Isognomon sanchuensis2 C. radiatostriata
T. (P.) sanchuensisCostocyrena radiatostriata
Costocyrena otsukai Costocyrena
matsukawaiNippononaia ryosekiana 295CH. matsukawaiN. ryosekiana
Fig. 10
Table 3. Morihita’s (1959) index for degree of interspecific
overlap in occurrence among 17 species from 15 samples.
Fig. 9. Degree of interspecific overlap in occurrence of 17 species
based on Morishita’s (1959) index.
:
210 Figs. 4 and 5 Ito and Matsukawa, 1997 AIsognomon sanchuensis I.
sanchuensisAr 0.84Cv0.98
Table 4 1989I. sanchuensis Isognomon I. sanchuensis Fig. 11
B 1995BCDE BP. (M.) plicata1.00H.
matsukawai0.39 T. (P.) sanchuensisC. radiatostriata 0.00T. (P.)
sp.0.25CH. matsukawai0.10 T. (P.) sanchuensis1.00C.
radiatostriata0.00D
Arcticidae gen. et sp. indet.1.00T. (P.) sanchuensis 0.28C.
radiatostriataT. (P.) sp.0.00ET. (P.)
sanchuensis0.33C. radiatostriata0.00 BH. matsukawai0.94
T. (P.) sanchuensis0.50T. (P.) sp.0.67C. radiatostriata
P. (M.) plicata1.00CH. matsukawai0.90 T. (P.) sanchuensis1.00C.
radiatostriata0.88D
Arcticidae gen. et sp. indet.1.00T. (P.) sanchuensis
0.80T. (P.) sp.0.50C. radiatostriata0.87E T. (P.) sanchuensis1.00C.
radiatostriata0.80 BP. (M.)
plicataArcticidae gen. et sp. indet. 1.001.00 0.000.39 0.501.00
1993BCDE 1995; Ito and Matsukawa, 1997 CDE C. radiatostriata Figs.
12 and 13 1978CDEC. radiatostriata BPanopea
(M.) plicataPanopea 4 Kondo,
1987BP. (M.) plicataL
Fig. 10. Occurrence of Costocyrena radiatostriata Tetoria (P.)
sanchuensis Assemblage (Scale bar shows 4 cm.).
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Table 4. Stratigraphic occurrence of molluscan species and their
individual numbers, individual numbers of left (L) and right (R)
valves, co-jointed valves (Co), existence index of left and right
valves (Cv) and articulation rate of shells (Ar) from the Sebayashi
Formation at loc. 210, Sebayashi, the Sanchu Cretaceous.
Fig. 11. Occurrence of Isognomon sanchuensis from the level A at
loc. 210, Sebayashi, the Sanchu Cretaceous.
:
113
55 220 H. matsukawai0.39T. (P.) sp.0.25T. (P.)
sanchuensisC. radiatostriata0.00 H. matsukawai0.94T. (P.)
sanchuensis0.50 T. (P.) sp.0.67C. radiatostriata1.00 1993BP. (M.)
plicata
H. matsukawai, T. (P.) sanchuensis,
T. (P.) sp.C. radiatostriata P. (M.) plicata H. matsukawai, T. (P.)
sanchuensis, T. (P.)
sp.C. radiatostriata 210 1995; Ito and Matsukawa, 1997
Fig. 13. Occurrence of Costocyrena radiatostriata at loc. 103,
Sebayashi, the Sanchu Cretaceous (Scale bar shows 4 cm.).
Fig. 12. Occurrence of Costocyrena radiatostriata from the level E
at loc. 210, Sebayashi, the Sanchu Cretaceous.
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radiatostriata T. (P.) sanchuensis C. otsukaiC. otsukai,
Isodomella shiroiensisT. (P.) sanchuensis C. radiatostriata T.
(P.)
sanchuensisC. radiatostriata, H.
matsukawaiT. (P.) sanchuensis
C. otsukaiC.
otsukaiT. (P.) sanchuensis Fig. 14 . C. otsukaiT. (P.)
sanchuensisC. otsukai Fig. 15 C. radiatostriata – T. (P.)
sanchuensis C. radiatostriata T. (P.) sanchuensisFig. 16 C.
radiatostriata – T. (P.) sanchuensis C. otsukai
Fig. 14. Comparison of individual numbers of nonmarine molluscan
fossils of the Shiroi Formation between shallow burrower and deep
burrower.
Fig. 15. A reconstruction of the molluscan paleocommunity of the
Shiroi Formation, the Sanchu Cretaceous.
:
Matsukawa and Ido1993 Plicatounio Plicatounio naktongensisP.
(P.) multiplicatus, Unio? ogamigoensis, Unio sp.Nagdongia
soni, Nagdongia sp., Nippononaia tetoriensisTrigonioides
Wakinoa tetoriensis, Pseudohyria? sp., “Batissa”antiqua Myrene
Mesocorbicula tetoriensisSphaerium sp. Tetoria Tetoria yokoyamai 2
Matsukawa and Ido1993 Morishita1959 Ostreidae gen. et sp.
indet.Myrene Mesocorbicula tetoriensisMyrene (M.)
tetoriensisTetoria Tetoria yokoyamaiSphaerium sp.Plicatounio
Plicatounio naktongensisTrigonioides Wakinoa tetoriensis 5 Tetoria
(T.) yokoyamai
Fig. 17. A reconstruction of the molluscan paleocommunity of the
Sebayashi Formation, the Sanchu Cretaceous.
Fig. 16. Comparison of individual numbers of nonmarine molluscan
fossils of the Sebayashi Formation between shallow burrower and
deep burrower.
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T. (T.) yokoyamai “Batissa” antiquaMyrene (M.) tetoriensis Myrene
(M.) tetoriensisisM.
(M.) tetoriensisT. (T.) yokoyamai Sphaerium sp.Sphaerium
sp.“Batissa” antiquaM. (M.) tetoriensis T. (T.) yokoyamai 3
Costocyrena radiatostriata Tetoria (P.) sanchuensis Costocyrena
radiatostriata Tetoria (P.) sanchuensis Myrene (M.)
tetoriensis
Tetoria (T.) yokoyamai Sphaerium sp. Costocyrena radiatostriata
Tetoria (P.)
sanchuensis
115 2 Isognomon sanchuensisCostocyrena
otsukaiC. radiatostriata Tetoria (P.) sanchuensis
3C. otsukai – T. (P.) sanchuensisC. radiatostriata
– T. (P.) sanchuensis
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