THE DISCOVERY OF THE RIGHT WHALE SKULL
IN THE KISAGATA SHELL BED
MASAHARU NISHIWAKI* AND YOSHIKAZU HASEGAWA**INTRODUCTION
A skull of a big whale was discovered during the excavation work of constructing
embankments at Kisagata Harbor, Akita Prefecture, on November 24, 1965. Theskull was subsequently treated to be kept at the Kisagata-cho Aquarium. The news
was delivered with photographs and a few materials to Nishiwaki through Prof.
Mitsumasa Hashimoto and Prof. Yaichiro Okada.
Nishiwaki and Hasegawa visited Kisagata to identify of what skull it was and towitness the place of excavation in the summer of 1966. The exact point of excavation, however, could not be witnessed because the construction of embankments had
been so advanced since the time of the discovery that the very point was not preserved as it had been. Consequently, informations of the situation and the environment of the discovery were collected and based on the observation on the exposed
strata of the other point near by, the level of the layer where the skull had beenburied in was presumed.
GEOLOGY
The skull had been buried in the lower part of the upper sand and gravel beds containning assemblages of molluscan shells. The result of the examination indicatesthat the beds ,,vere accumlated near the ancient coast line. Development of coastal
dunes is remarkable in the area around the Kisagata Harbor. The thickness of dunesands near by the harbor is 1 to 2m. Under the dune sand, lies sand and gravel
beds, 4 to 5m thick, are divided into two parts oflayers by the border of milky white
precipitate derived from mineral springs. Although there is no special difference
between the two parts, the lower layers contained comparatively larger gravels.
In the case of recognizing above mentioned border, the two parts can be separated.
Kisagata Shell Bed: The upper part of the upper sand and gravel beds isnamed here as the Kisagata Shell Bed. This layer is seen partly lenticular. The
following 15 species were found in it, but Serpulorbis imbricatus and Ostrea gigas weremost dominant in number.
1. Tegula (Omphalius) rustica (GMELIN)
2. Serpulorbis imbricatus (DUNKER)
3. Batillaria multiformis (LISCHKE)
4. Neverita (Glossaulax) didyma (RODING)
5. Purpura (Mancinella) davigera KUSTER* Ocean Research Institute, University of Tokyo.
** Section of Vertebrate Paleontology, National Science Museum.
79

80

NISHIWAKI AND HASEGAWA

6.
7.
8.
9.
10.
11.
12.
13.
14.
15.

Babylonia japonica (REEVE)
Oliva mustelina LAMARCK
Narona (Solatia) nodulifera (SOWERBY)
Pseudogrammatodon dalli (SMITH)
Anadara (Scapharca) subcrenata (LISCHKE)
A. (S.) broughtonii (SCHRENCK)
Ostrea (Crassostrea) gigas THUNBERG
Protothaca jedoensis (LISCHKE)
Macoma incongrua (V. MARTENS)Heteromacomayantaiensis (GROSSE et DEBEAOX)

lOOOm

011111111111111111111!

Fig. I.

The place ( x) where the skull was found: Kisagata-cho, Akita Prefecture.

All the species are living ones, they inhabit along the coasts near the low tidelevel in Honshu and other southern islands ofJapan. Ostrea and Serpulorbis are often
found adhered collectively to the surface of boulders, this indicates that these species
are indigenous to the locality. Discovery of this bed, especially densely contained
gravel and shell, verify the ancinet coastline.
According to Gakuro Inamura (1942), the Kisagata area had once been thepicturesque sea dotted with literally numberless islets (Fig. 2), however, in 1804 a

RIGHT WHALE SKULL

81

great earthquake happened, which caused the upheaval of ground and the beautiful
sea was destroyed. The greater part of the area has turned to be paddy fields.
The layer in which the skull was found, was also a bed of sand and gravel mixture, lied just under the Kisagata Shell Bed and about 4m deep from the groundsurface. Buried under the layer of coastal deposits, it is evident, the skull had beenthere since some time before 1804. However, nothing more can be presumed.

Fig. 2. The picture of the Kisagata area drawn by a local painter before the greatearthquake in 1804. The scenery is the beautiful sea dotted with a great number ofislets, known by the name of " ninetynine islets". The point of the discovery is at
the lower right corner.

EXAMINATION ON THE SPECIMEN
The squamosal was protruded horizontally, the mastoid process was largely swelling
down, and compared the shape and the measured values of the occipital condyles
with that of the living right whale, close similarity between them was found. Thendiscovered specimen can be identified as a right posterior part of skull of a right whale,
Eubalaena glacialis. The skull had not been much fossilized. The whole skull, especially the part of occipital condyles were seen worn out and a stone of a human fistsize had cracked into it. If readers reffer the formally published report by Omura(1958, and the report contained in this volume) in which the skeletons of this species
are described, above comparison can be understood well.
This is the first record of discovery of part of remain of a right whale in thesediment on the coast of the Sea of Japan.

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NISHIWAKI AND HASEGAWA

According to Tawnsend (1935), a considerable number of right whale population was found in the Sea of Japan about 100 years ago. Although in the North
Pacific, several hundreds of right whale are presumed to be inhabited today and thenumber of whales seems to be increasing, very few have been found in the Sea ofJapan. (Tago, 1900; Matsuura, 1936; Kuroda, 1938, 1940; Tomilin, 1957;
Nishiwaki, 1965, 1967)
TABLE 1.

DIMENSIONS OF THE SPECIMEN

Distance between center of ventral part of occipital condyles and outer end ofsquamosalDistance between basal part of mastoid process and outer end of squamosal
Minimum height of squamosal at posterior end
Minimum antero-posterior length of squamosal
Antero-posterior length of mastoid process
Maximum width of mastoid process
Length of alar canali'dimimum breadth ofvomer
Distance between posterior end of occipital condyles and posterior edge of alar canalMaximum thickness of occipital condyles (horizontal)
Height of occipital condyle (vertical)
Maximum breadth of occipital condyle
JVIaximum breadth offoramen magnum
Length of a part of premaxilla
JVIaximum width of a part of premaxilla
Anterior width of a part ofpremaxilla
Thickness of premaxilla at sutual end

cm150904343
454021177442 +35+21 +
14160
1640
14ACKNOWLEDGEMENTS

At the presentation of this report, the authors express sincere gratitude to Dr. Yo K.
Okada, former director of the National Science Museum, Prof. Yaichiro Okada of
Tokai University, Prof. Mitsumasa Hashimoto of Akita University and Mr. Yuichi
Mori of the Japan Society for the Promotion of Science for giving chance to meet thediscovery of the skull in the Kisagata Shell Bed.
Thanks are also due to Mr. Y oshiya Suda and Keiichi Nitta of the Kisagata
Town Office for collecting informations at the place of excavation and taking trouble
to help them in many ways.
The authors are deeply indebted to Dr. Tadashige Habe of the National Science
Museum and Dr. Kiyotaka Chinzei of the University of Tokyo for cooperation inidentification of the species of shells. The junior author is particularly indebted toProf. Fuyuji Takai, Prof. Tetsuro Hanai, Dr. Arata Sugimura and Dr. Yasuhide
Iwasaki of the University of Tokyo, as well as Dr. Hiroshi Ozaki of the National
Science Museum for kind advices.
Acknowledgement is made of the partial financial support of this study throughgrants from the Japan Society for the Promotion of Science as part of the U.S.J a pan Cooperative Science Program.

RIGHT WHALE SKULL

83

REFERENCES
lMA:-.IURA, G. and Y. OGASAWARA., 1942, Transfiguration by Kisagata Earthquake. Kagaku, 12: 18-19.
(in Japanese)
KuRODA, N., 1938. A list of the Japanese mammals. Published by author. 121- - , 1940. A monograph of the Japanese mammals. 311, pls. 48. Tokyo. (in Japanese):MATSUURA, Y., 1936. On the right whale in the Japanese waters. Plants and Animals, 4: 696-702. (inJapanese)
NrsmwAKr, M., 1965. Whales and Pinnipeds. Univ. of Tokyo Press. 439. (in Japanese)- - , 1967. Distribution and Migration of Marine Mammals in the North Pacific Area. Bull. Ocean. Res.
Inst., Univ. of Tokyo. 1: 1-64.
OMURA, H., 1958. North Pacific right whale. Sci. Rep. Whale Res. Inst., Tokyo. 13: 1-52.
TAGO, K., 1922. On the whales in the Japanese waters. Z,ool. i'vfag., Tokyo. 34: 446-479. (in Japanese)
ToMILIN, A. G., 1957. Cetaceans; Mammals of USSR and adjacent countries, Vol. IX. Akademi Nauk SSSR,lvfoscow. 756. (in Russian)
TOWNSEND, C. H., 1935. The distribution of certain whales as shown by logbook records of American whaleships. :(,oologica. 19: 1-50.

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NISHIWAKI AND HASEGAWA

EXPLANATION OF PLATESPLATE I.
A. Environment of the spot of discovery.
1. Dune sand at surface.
2. Upper sand and gravel bed.
X. approximate locality of the skull
B. Shells in the Kisagata Shell Bed.
C. Enlarged part of B.
Surpulorbis and Ostrea are seen adhered to the surface ofa boulder.
PLATE II.
A. Mineral spring's precipitate seen in the bed, and the constructing embankment at the south sideof the bay is seen in the left.
2. Upper bed.
3. Lower bed.
B. Mineral spring predcipitate is seen between the upper and lower beds. The scene B is continued eastwared to scene A.
C. Shell bed (Sb), near by the scene B.
I. Dune sand.
2. Upper sand and gravel beds consist of coarse sand mixed with dispersed gravel.
PLATE III. Photographs of the specimen.
A. Caudal view of the specimen.
B. Ventral view of the specimen.
C. A part of left premaxilla of the specimen.
D. A part ofleft premaxilla of the specimen.

(outer side)(ventral side)

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