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

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
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