Morphometrics of Flightlessness in the Alcidae
Abstract Data collected from skin specimens of the 23 Recent species of Alcidae, skeletal material for Recent and fossil alcids, and published data on body mass and wing area were used to describe the morphometric characteristics of flightlessness in the Great Auk (Pinguinus impennis) and the fossil...
| Published in: | The Auk |
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| Main Author: | |
| Format: | Article in Journal/Newspaper |
| Language: | English |
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Oxford University Press (OUP)
1988
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| Online Access: | http://dx.doi.org/10.1093/auk/105.4.681 http://academic.oup.com/auk/article-pdf/105/4/681/30083921/auk0681.pdf |
| Summary: | Abstract Data collected from skin specimens of the 23 Recent species of Alcidae, skeletal material for Recent and fossil alcids, and published data on body mass and wing area were used to describe the morphometric characteristics of flightlessness in the Great Auk (Pinguinus impennis) and the fossil mancalline auks. A regression equation confirmed a body-mass estimate (5 kg) for P. impennis (Bédard 1969). The size and relatively small wings produced wing-loading of roughly 22 g· cm-2, comparable to those of medium-sized penguins. Multivariate analysis of external measurements underscored the uniquely large size, relatively short wings, and moderately deep bill of Pinguinus compared to other Recent alcids. Analysis of skeletal measurements revealed that the genera of flightless Alcidae (Pinguinus, Mancalla, Praemancalla, and Alcodes) were characterized by relatively short distal wing elements and dorsoventral flattening of all major wing elements, in combination with relatively large core and pelvic dimensions. These differences were most pronounced in Mancalla, moderately developed in Praemancalla, and smallest in Pinguinus. Estimated body mass (1-4 kg) for selected fossil mancallines exceeded the largest flighted alcids (Uria) but was less than for Pinguinus. Pinguinus was a comparatively large piscivore sharing many morphological features with the Razorbill (Alca torda) and murres (Uria spp.). Its flightlessness evidently was a consequence of extreme specialization for pursuit diving, convergent with that of the Spheniscidae. Loss of flight imposed significant requirements on breeding sites and foraging habitats of the Great Auk and presumably the mancallines, and rendered Pinguinus exceptionally vulnerable to human exploitation. |
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