(Odontopterygiformes) from the Ashiya Group (Oligocene), Japan

Transcription

1 Bull. Kitakyusku Mus. Nat. Hist., 9: December 31, 1989 An occurrence offossil bony-toothed bird (Odontopterygiformes) from the Ashiya Group (Oligocene), Japan Yoshihiko Okazaki Kitakyushu Museum of Natural History, Nishihonmachi 3, Yahatahigashiku, Kitakyushu 805, Japan. (Received October 31, 1989) Abstract An incomplete humer bone of odontopterygid bird is reported from the Oligocene Ashiya Group, Northern Kyushu,Japan. The length of humer bone is very large, suggesting the wing span of about 6 meters. The affinity of marine bird assemblage of the Ashiya Group to the Iwaki Group, Northeastern Honshu, is empha sized as they both yield plotopterygid and odontopterygid birds. Introduction On December , one bone fossil specimen from the Ashiya Group, North Kyushu was brought to the Kitakyushu Museum of Natural History. That was a large humer bone of a bird, reaching 60cm long, with several fragmental wing-bones. The specimen had been stored by Mr. Masayuki Sadasue, Principal of the Asagi Primary School, Onga-cho. He obtained the specimen from a quarry worker of Mizumaki-cho, through his geological research along the Onga River (mainly sur veyed in 1974). From the same district, several fossil specimens of plotopterygid bird have been reported (Hasegawaet al., 1979). But the present specimen is much larger than plotopterygid humer, that is less than 25 cm. The large size and thin bone wall indicates the humer to be included in the odontopterygid bird. The presence of the odontopterygid bird in the Japanese Tertiary has been reported from five localities (Table 1), from the Oligocene to Pliocene. As the geological age of the Ashiya vertebrate Fauna (Okazaki 1988, etc.) is Oligocene, specimens of the Iwaki City are of the same age among thejapanese odontopterygid birds. Table 1. Japanese fossils ofodontopterygid birds Location Part Age Reference Mizumaki, Fukuoka Pref. humerus Oligocene present report Iwaki, Fukushima Pref. rostrum, radius Oligocene Hasegawa et al., 1986 Chichibu, Saitama Pref. quadrate M. Miocene Ono, 1989 Mizunami, Gifu Pref. no report M. Miocene Ono, 1989 Maesawa, Iwate Pref. humerus Pliocene Ono et al., 1985 Kakegawa, Shizuoka Pref. femur Pliocene Ono et al., 1985

2 124 Yoshihiko Okazaki The author expresses his sincere thanks to Mr. Masayuki Sadasue for he kindly donated specimens to study, and Mr. Kuniomi Hirano, Kitakyushu Natural History Society who helped field activities; Also, Dr. Yoshikazu Hasegawa, Yokohama National University, Dr Keiichi Ono, National Science Museum, Osamu Sakamoto, Saitama Prefectural Museum of Natural History, and the persons of the Kitakyushu Museum of Natural History, for their suggestions and encouragements during the study. Systematic description order Odontopterygiformes Howard 1957 Family, genus, and species indet. Mizumaki specimen; left humerus with several fragmental wing bones. 000, 013 KMNH VP SMizumakifig. 1. Locality of the Mizumaki Specimen. X Mizumaki Speciman. 38 Orio Specimen (plotopterygid).

3 Bony-toothed bird from the Ashiya Group 125 Locality; Yoshida Miyao, near eastern boundary of the Mizumaki-cho, Fukuoka Prefecture, Japan. (130 42'44*E, 33 50'45*N) Horizon; Yamaga Formation, Ashiya Group. Discovery; by a quarry worker in about Description; Shaft and distal part of humerus preserved, but proximal end destroyed; shaft almost straight, depressed in anconal-palmar direction. Wall of bone shaft compact and very thin, about 2 mm and less than 1mm in thinner part. In articular part, inner surface of the bone wall with weak sponge structure, but in shaft part, inner surfacesmooth. At the broken part, where internal mould is observed, six periodical transverse inner ridges are seen in posterior part. Shaft somewhat diagonal in transverse section, with a ridge, compared to deltoid crest, along lateral margin near proximal end. In anconal view, entepicondyle and external condyle prominent. Olecranal fossa shallow. In palmar view, external condyle very prominent, internal condyle also prominent, intercondylar furrow shallow, entepicondyle very prominent. Beside the humer bone, several fragmental long bones are seen in the same slab; (1) Two long bones beside the distal end of the humerus, about 7 cm and 5 cm in length, circular section with shallow longitudinal furrow; may be parts of carpometacarpus. (2) A long bone fragment beside thecentral part ofthe humerus; may be the digit 2, phalanx 1. Measurements; Followings are measured in mm. total length as preserved (including mould) 619 width of shaft at the narrowest part 33.7 width of shaft at the distal end of deltoid crest 38.6 anconal-palmar thickness at the distal end of deltoid crest 13.1 width of distal articulation 62.9 thickness of distal articulation 33.0 Discussion and conclusion The present specimen of bird humer bone from the Oligocene Ashiya Group is identified as the Odontopterygiformes. This identification is depended on the extraordinal large size of the bone, depressed shape of section in anconal-palmar direction, shallow olecranal fossa, and thin and compact bone wall of the shaft. Present report is the first record of odontopterygid bird from the Ashiya Group. The Ashiya Group yields many fossils of plotopterygid birds as already reported (Hasegawa etal., 1979), but plotopterygid humer is much smaller, with curved shaft and more improminent condyles in its distal articulation. The size of present humer bone is rather large even in the odonjopterygians, and

4 126 Yoshihiko Okazaki the estimation of the wing span is attempted. Preserved shaft of the present humer (61.9 cm, including mould) has weak expansion in its anterior proximal part, correlated as distal end of the doltoid crest. Lost length of proximal part ofhumer is estimated as 19.3 cm, calculated from the figure of presented by Lartet, 1857 (Pelagornis miocaenus). Howard (1957) estimated the ratio of wing span against humer to be 7.29 {Osteodontornis orri; 16 feet/ 593 mm plus 3 inches). The wing span of the present bird, therefore, is estimated as 592 cm. Internal periodical ridges seen in the present specimen may serve as reinforce structure of the bone. As already noted, there are five localities of odontopterygid fossils in Japan. Among them, Iwaki Formation also yields many plotopterygid birds, and there is close similarity between these two sediments in this viewpoint. This similarity can not been traced in cetacean faunas (Okazaki 1988), because the Iwaki Formation yields scarce cetacean fossils. Reference Alexander, R. M. (1989) Dynamics of Dinosaurs and other extinct Giants. Columbia Univ. Press, Feduccia, A. (1980) The Ageoj Birds. Harvard Univ. Press, Harrison, J. O. and Walker, C. A. (1976) A Review of the bony-toothed birds (Odontopterygiformes): with descriptions of some new species. Tertiary Res., Spec. Pap. 2: 1-62, pis Hasegawa, Y. etal. (1979) Preliminary Noteson the Oligo-Miocene Penguin-like Birds from Japan (Parts 1-7). Bull. Kitakyushu Mus. Nat. Hist. 1: 41-60, pis (in Japanese) Hasegawa, Y., Ono, K. and Koda, Y. (1986) Odontopterygid bird from the Oligocene Iwaki Group. Abslr Ann. Meeting Palaeontol. Soc. Japan, 24. (injapanese) Howard, H. (1957) A gigantic "toothed" marine bird from the Miocene ofcalifornia. Santa Barbara Mus. Nat. Hist., Dept. Geol. Bull. 1: 1-23, 8 figs. Howard, H. and Walter, S. L. (1969) A new species of bony-toothed bird (Family Pseudodontornithidae) from the Tertiary of New Zealand. Proc. Canterbury Mus. 8 (4): Lartet, E. (1857) Note sur un humerus fossild d'oiseau, attribue a un tres grand Palmipeda de la section des Longipennes. C. r. hebd. Seanc. Acad. Sci., Paris, 44, , pi. 45. Okazaki, Y. (1988) Oligocene squalodont (Cetacea: Mammalia) from the Ashiya group, Japan. Bull. Kitakyushu Mus. Nat. Hist. 8: 75-80, pi. 1. Ono, K. (1980) Pliocene Tubinare Bird from Kakegawa, Shizuoka Prefecture, Japan. Mem. Natn. Sci. Mus. 13: 29-34, pi. 2. Ono, K. (1989) A Bony-toothed Bird from the Middle Miocene, Chichibu Basin, Japan. Bull. Natn. Sci. Mus., Ser. C, 15 (1): Ono, K., Y. Hasegawa, and T. Kawakami (1985) First record of the Pliocene bony-toothed bird (Odontopterygiformes) from Japan. Bull. Iwate Pref. Mus. 3: , pis. 1, 5. (in Japanese with English Summary) Scarlet, R. J. (1972) Bone of a presumed Odontopterygian bird from the Miocene of New Zealand. N. Z.Jour. Geol. Geophys. 15 (2):

5 An occurrence of fossil bony-toothed bird (Odontopterygiformes) from the Ashiya Group (Oligocene), Japan Yoshihiko Okazaki Plate 1

6 Explanation of Plate Plate 1 fig. 1. fig. 2. fig. 3. fig. 4. Odontopterygiformes, gen. et sp. indet. KMNH VP 000, 013 Left humerus from Mizumaki-cho, Fukuoka Prefecture, anconal view X0.25 section in near deltoid crest X0.5 close view ofdistal part X0.5 palmar view of articulation X0.5

7 Okazaki, Y. Bony-toothed bird from the Ashiya Group Plate 1