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| Pelagornis miocaenus ： ウィキペディア英語版 |
Pelagornis
''Pelagornis'' is a widespread genus of the prehistoric pseudotooth birds. These were probably rather close relatives of either pelicans and storks, or of waterfowl, and are here placed in the order Odontopterygiformes to account for this uncertainty.〔Bourdon (2005), Mayr (2009: p. 59)〕
==Description==
The fossil specimens show that ''P. miocaenus'' was one of the large pseudotooth birds, hardly less in size than ''Osteodontornis'' or the older ''Dasornis''. Its head must have been about long in life, and its wingspan was probably more than , perhaps closer to 6 m (20 ft). Unlike in its contemporary ''Osteodontornis'' but like in the older ''Pseudodontornis'', between each two of ''Pelagorniss large "teeth" was a single smaller one. ''Pelagornis'' differed from ''Dasornis'' and its smaller contemporary ''Odontopteryx'' in having no pneumatic foramen in the fossa pneumotricipitalis of the humerus, a single long latissimus dorsi muscle attachment site on the humerus instead of two distinct segments, and no prominent ligamentum collaterale ventrale attachment knob on the ulna. Further differences between ''Odontopteryx'' and ''Pelagornis'' are found in the tarsometatarsus: in the latter, it has a deep fossa of the hallux' first metatarsal bone, whereas its middle-toe trochlea is not conspicuously expanded forward. The salt glands inside the eye sockets were extremely large and well-developed in ''Pelagornis''. From the humerus pieces of specimen LACM 127875, found in the Eo-Oligocene Pittsburg Bluff Formation near Mist, Oregon (USA), ''P. miocaenus'' differs in an external tuberosity that is not as much extended shoulderwards and that is separated from the elbow end by a wider depression. The head of the humerus is turned more to the inward side and the large protuberance found there is not as far towards the end. The Waipara River humerus mentioned above agrees with ''P. miocaenus'' in that respect. If the Oregon fossils are related to ''Cyphornis'' and/or ''Osteodontornis'', and if the traits as found in ''P. miocaenus'' and the New Zealand specimen are apomorphic, the latter two may indeed be very close relatives.〔Olson (1985: p. 198), Goedert (1989), Rincón R. & Stucchi (2003), Bourdon (2005), Mayr (2008), Mayr ''et al.'' (2008)〕
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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