Variation in Numbers of Scleral Ossicles and Thier Phylogenetic Transformations Within the Pelecaniformes
1989; Oxford University Press; Volume: 106; Issue: 3 Linguagem: Inglês
ISSN
1938-4254
AutoresKenneth I. Warheit, David A. Good, Kevin de Queiroz,
Tópico(s)Amphibian and Reptile Biology
Resumo-We examined scleral rings from 44 species of Pelecaniformes and found nonrandom variation in numbers of scleral ossicles among genera, but little or no variability within genera. Phaethon, Fregata, and Pelecanus retain the primitive 15 ossicles per ring, while the most recent common ancestor of the Sulae (Phalacrocoracidae, Anhinga, and Sulidae) is inferred to have had a derived reduction to 12 or 13 ossicles. Within the Sulidae, Sula (sensu stricto) exhibits further reduction to 10 ossicles. These patterns of ossicle reduction are congruent with both Cracraft's hypothesis of pelecaniform relationships (1985) and that of Sibley et al. (1988). The presence of scleral rings in museum specimens is significantly greater for Phaethon and Fregata, and less for Pelecanus, than would be expected from a random distribution. We conclude that the scieral ring is of potential systematic importance, and we make recommendations for its preservation in museum collections. Received 11 August 1988, accepted
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