U字型の吻部は、

の頭骨の主たる特徴となっている。著者のひとりの大石は以前にナガスクジラ科鯨類の下顎骨の研究で、吻部の形態と密接な関係がある下顎骨について、次のように指摘した。の下顎骨は、水平面に置いたとき、関節部が内旋し筋突起が上方へのびるという独特の特徴をもつ。これに対してクロミンククジラでは、下顎骨は内旋せず、筋突起が上外方へのびる。両者の違いは吻部の形態に対応する。のU字型の吻部は下顎骨の長軸方向での内旋を必要としないが、クロミンククジラでは、口を閉じた状態で下顎骨とV字型の吻部との間の隙間を最小にするために下顎骨が内旋する。この状態では、クロミンククジラの下顎骨の関節部は内旋することになる。つまり、口を閉じたときにはもクロミンククジラも関節の状態は同等である。本研究では、3DCGソフトを使って上記のことを検証した。3Dシミュレーションの結果、大石の以前の研究の有効性が認められ、さらに下顎骨挙上時に下顎骨がわずかに内旋することが新たにわかった。鯨類のような巨大な頭骨について、3DCGで以上のような状況を確かめることができる。

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のひげよりとれた脂質について成分検索の結果, 約20%のステリンを抽出することができステリンの大部分がコレステリンであることを確認した。なお, 組成脂肪酸は主としてモノエテノイド酸からなるように思われる。

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The blue whale is the world’s largest animal. We can see a life-size model of a blue whale in front of the National Science Museum in Tokyo. We found it very exciting. However, we are not able to see blue whales in the sea around Japan. Blue whales still show little sign of recovery in the North Pacific area even after the whaling prohibition. We don’t know sufficiently either the actual number of blue whales or their behavior. We had good opportunities to see blue whales in the Sea of Cortez and off California between 1995-1998. We present some topics from what we obtained during the last four years of our survey. 1) Photo identification: Researchers have taken black and white photographs of individuals for the photo identification. They use the pigmentation pattern of the blue whale body surface for identification in Quebec, Canada (Sears 1988). We have taken color pictures and video footages by ourselves in our study. Photographic identification of individuals has shown new information on the migration and behavioral patterns of blue whales. From the blue whale pictures we found that each dorsal fin have clear difference-useful for identification. We can recognize there are several types of dorsal fin shapes in our pictures. We have classified the dorsal fin patterns mto categones. 2) Feeding behavior: Blue whales feed on krill in the Sea of Cortez Baja, California. Blue whale’s head breaks the surface, and we see the white big blow. Then the broad U-shaped head disappears. We can then smell the krill in the air. The krill that blue whales eat are very small. We have sometimes seen feeding behavior of blue whales in our study. It is true that Blue whales feed off Baja California in Spring. 3) Mother and Calf: We had good opportunity to see a mother and calf together in our survey. The calf was swimming with its mother side by side. We think this is the nursing behavior. We have seen the feeding behavior of a blue whale with a little calf in the Sea of Cortez, too. We will maintain our research of Blue whales in order to obtain more results. Our study has just begun. We think the photographic identification of individual whales must be useful in the study of migration of blue whales and their population size.

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The number of blue whales throughout the world has only made a small recovery. After the whaling days, in the beginning of 1992, blue whales began showing up in small numbers along the coast of California and Baja California. Researchers have identified many blue whales by photographing areas around their dorsal fins and flukes. Over 800 individuals have already been identified off the California coast from Mexico to Oregon. We have contributed by taking photos and viedeos. Photographic identification of individuals has given new information including behavioral patterns of blue whales. We think that it is useful for studying the migration of blue whales and their population. We had good opportunities to see them sometimes during 1994-2000. Over the years, it seems that blue whales are becoming used to the presence of our boats. Also we have taken photos of sperm whales and killer whales for identification in our survey. It is very useful to know their population and it is very important to know the relationship between the individual whales. We will introduce our topics with photos.

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The evolutionary deformation of mysticete skulls known as telescoping consists mainly of backward interdigitation of the medial rostral elements and forward overthrust of the occipital elements. It is assumed that both movements had a influence upon the development of other cranial elements such as those around the subtemporal fossa. Morphological characters around the subtemporal fossae of balaenopterid whales were examined in order to clarify diagnoses of species. In Balaenoptera acutorostrata and Balaenoptera edeni the alisphenoid has contact with the parietal, pterygoid, and squamosal; and does not form a part of the optic tube. On the contrary the alisphenoid of Balaenoptera borealis forms a small wall of the optic tube; and has contact with the parietal and pterygoid. In Balaenoptera physalus there are many variations in the manner of exposure of the alisphenoids. The alisphenoid of Sibbaldius musculus has contact with the parietal and pterygoid, and sometimes with the squamosal. In Megaptera novaeangliae as far as the examined specimens are concerned the alisphenoids are exclusively not exposed. In B. acutorostrata and B. edeni the foramen pseudo-ovale opens in the anteromedial comer of the glenoid fossa of the squamosal. The falciform process of B. edeni is longer than that of B. acutorostrata. The foramen pseudo-ovale of B. borealis is elliptical and opens around the medial portion of the crest between the subtemporal fossa and glenoid fossa. The falciform process of B. borealis develops much less than B. edeni. The foramen pseudo-ovale of B. physalus is round and opens on the medial portion of the crest between both the fossae; and is surrounded by the pterygoid and squamosal. In S. musculus and S. musculus brevicauda the foramen pseudo-ovale surrounded almost only by the squamosal opens around the medial portion of the crest. The foramen pseudo-ovale of M. novaeangliae opens on the medial portion of the narrow crest between the subtemporal and glenoid fossae, and is surrounded almost only by the squamosal. Although the alisphenoid of Late Eocene archaeocete Zygorhiza is exposed extensively as in terrestrial mammals, Early to Middle Miocene cetotheres such as Parietobalaena and Diorocetus remarkably diminished their alisphenoids. And recent balaenopterids, whose skulls are highly telescoped, have alisphenoids scarcely exposed. A broad width of the portion between the lateral and inferior laminae of the pterygoid in B. physalus separates the squamosal from the palatine in the medial margin of the subtemporal fossa; however, the squamosal of S. muscuｌus makes broad contact with the posterior margin of the palatine. Overlap of bones seen in the subtemporal fossae of balaenopterid whales seems to represent a mode of telescoping.

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日本の近代鯨類学の草創期における東洋捕鯨株式会社とロイ・チャップマン・アンドリュースの影響を文書資料から調べた。東洋捕鯨の前身会社はナガスクジラと

について社内名称を生物学的種に基づいて固定し、それが標準和名として使用されるようになった。アンドリュースはひげ鯨に加え、歯鯨でも日本近海個体について初めて標本の観察から学名を比定した先駆者であった。そのような認識は当時の日本の動物学者も持ちあわせ、永澤六郎教授はアンドリュースと手紙で議論した結果を日本産鯨類の学名比定の論文に反映させていた。東洋捕鯨が社内名称として生物学的種の呼称を使用したこと、アンドリュースが標本を観察して学名を比定したこと、この実践が日本の鯨類学の近代化の端緒となった。

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Baleen whales (suborder Mysticeti) comprise eleven extant species that are classified into four families. Although several phylogenetic hypotheses about these taxa have been proposed, their phylogenetic relationships still remain confusing. SINE (short interspersed repetitive element) insertion data are now regarded as almost ideal shared derived characters at the molecular level, and we have applied this method to this problem. Here, we successfully reconstruct the phylogenetic relationships of these whales by characterizing 40 informative SINE loci. One of the intriguing conclusions is that balaenopterids and eschrichtiids radiated very rapidly during a very short evolutionary period. During this period, when newly inserted SINE loci retained ancestral polymorphisms, speciation occurred and these SINEs were sorted incompletely into each lineage, thus resulting in inconsistencies regarding the presence or absence of the SINE. This is in sharp contrast to the phylogeny of toothed whales, for which no SINE inconsistencies have been found. Furthermore, we found monophyletic groupings between humpback and fin whales, and also between (sei + Bryde's) and blue whales, both of which have not previously been recognized. The comprehensive SINE insertion data, together with the mitochondrial DNA phylogeny that was recently completed, provide a nearly complete picture of the evolutionary history of baleen whales.

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A partial mysticete skull (Order Cetacea) was discovered in the early Pleistocene (1.2-1.0Ma) Setana Formation at Kuromatsunai, Hokkaido, Japan. We have identified it as a member of the family Balaenopteridae gen. et sp. indet. based on features of the occipital region. The breadth of the occipital is within the adult range of the recent species Balaenoptera brydei, B. borealis, and B. physalus or B. musculus. This fossil indicates that very large species of the family Balaenopteridae had evolved and radiated before the early Pleistocene.

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ロイ・チャップマン・アンドリュースが1910年にスミソニアン協会アルバトロス号のフィリピン調査に参加した後、日本で行った鯨類調査と1912年朝鮮で行った鯨類調査の足取りを復原した。調査はニューヨークのアメリカ自然史博物館（AMNH）に保管されているアンドリュースが収集した鯨類標本や手紙、報告書、写真、調査日誌を資料とした。アンドリュースは紀伊大島では8頭の鯨を調べ3個体分の全身骨格を確保した。鮎川では62頭以上を調査し、巨大なオスのマッコウクジラの骨格を収集した。蔚山ではコククジラ23頭含む32頭の鯨を調べ、全身骨格も収集した。これらの調査活動が可能になったのは東洋捕鯨の社員や現場従業員、本社や事業場の全面的な協力によるものであった。東洋捕鯨は別にツチクジラやシャチの骨格も寄贈している。マッコウクジラ、ツチクジラ、シャチの骨格標本はアメリカ自然史博物館で1933–1962年の間に展示されていた。コククジラの標本はスミソニアン協会国立自然史博物館で1960年代始めから現在に到るまで展示されている。彼は他にも横浜、日光、神戸、門司、台湾、沖縄、土佐清水、そして瀬戸内海にも立ち寄り写真を撮った。紀伊大島と鮎川、蔚山の写真は近代捕鯨の初期の姿を写した唯一のまとまった写真であり、アンドリュースの写真や文書は、生物学的にも文化人類学的にも将来の貴重な研究資料である。

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This study describes a previously undescribed fossil physeterid from the Pleistocene of Tokyo. This fossil physeterid was recovered from the Early Pleistocene, Fukushima Formation (ca. 1.60‒1.77 Ma), Kazusa Group in 1971 and has long been known as “Hino Kujira” without detailed descriptions. The specimen consists of fragments of the left maxilla, and we estimate the original size of the maxilla can reach at least 3 m long, suggesting an individual at least 11.5 m long. The maxilla is dorsoventrally thick (eroded, but at least 188 mm), and such a thick maxilla clearly differs from that of mysticetes but is similar to that of the modern sperm whale, Physeter macrocephalus. In addition, the average size of each pore on the spongy bone under the compact bone layer is prominent (10 to 15 mm in diameter), consistent with the macroporous structure of the maxilla of modern Physeter macrocephalus. We then provisionally make the taxonomic assignment of this Pleistocene specimen as Physeter sp. Besides, we review seventy-three documented fossil cetaceans from the Pleistocene of Japan, suggesting that the known paleodiversity of the Japanese Pleistocene cetaceans (12 genera) is much lower than that of modern composition (26 genera). This evident discrepancy likely results from the research effort that currently only produces an inadequately known fossil record of cetaceans.

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