日本の恐竜化石は１道18県から知られており，北陸地域の手取層群からは現在６種の恐竜化石が新属新種として記載されている．こうした北陸地域の恐竜化石のあらましを紹介し，福井県勝山市北谷からの勝山恐竜フォーナと石川県白山市白峰地域からの白峰恐竜フォーナで代表される手取恐竜フォーナについて概説する．

抄録全体を表示

 The uppermost Jurassic to Lower Cretaceous Tetori Group is the shallow marine to non-marine siliciclastic stratum in northern Central Japan. Abundant plant macrofossils, marine to freshwater molluscs, and terrestrial vertebrate fossils have been described from this group. The fossils from the Tetori Group represents the biota lived in mid-latitudes of the eastern margin of the Asian Continent and of the Northwest Pacific at that time. The studies of the Tetori Biota provide the clues to reconstructing the palaeobiogeography in East Asia and the Northwest Pacific.

抄録全体を表示

 A right lunar of the Rhinocerotidae (Mammalia, Perissodactyla) from the Pliocene Ueno Formation of the Kobiwako Group, central Japan is reappraised and described. This specimen is large among the lunars of mammals, mushroom-shaped in anterior and proximal view, and triangular in lateral view, indicating that it is assigned to the Rhinocerotidae. It is assigned to the tribe Rhinocerotini in having a third scaphoid facet and a caudal prolongation of the pyramidal facet. It is similar in morphology to that of a Rhinocerotini Stephanorhinus in having an ulna facet, an acute distal end of the anterior apophysis, a keel-shaped anterior apophysis, a wide proximal part, and a similar overall shape and size that are indicated by a ratio diagram. However, the generic identification of this specimen is difficult due to the scarcity of the material. This study indicates that the Rhinocerotini existed in the Pliocene of Japan, for the first time.

抄録全体を表示

 The smalltooth sandtiger shark, Odontaspis ferox (Risso 1810), is an enigmatic modern lamniform shark. In this study, a ʻsingle-sampleʼ paleontological technique previously used to examine the growth patterns of some fossil sharks is applied to a specimen of extant O. ferox of an unknown sex that measured 297 cm in total length (TL). Growth increments presumably deposited annually identified in its vertebrae suggest that the O. ferox individual was 14 years old at the time of its capture. The von Bertalanffy growth function experimentally fitted to the data gives the following growth parameters: L ₀ = 93.850 cm TL, L_∞ = 315.206 cm TL, and k = 0 .183 yr^–1. The L_∞ value strongly suggests that the specimen must have been a male, and the size at birth and size at maturity based on our study agree well with published field-based observations on O. ferox. Where O. ferox occurs in the fossil record as far back as in the early Miocene, this study also presents a method to infer the TL from an isolated tooth for O. ferox, useful for paleoecological reconstruction.

抄録全体を表示