Meeting Abstract
P2.67 Friday, Jan. 4 Postcranial skeletal pneumaticity in charadriiform birds: Re-examining relationships among skeletal pneumaticity, body size and diving behavior O’CONNOR, P.M.*; DUNCKER, H.-R.; Ohio Univ; Univ of Giessen oconnorp@ohiou.edu
Recent studies have documented repeated patterns between the extent of postcranial skeletal pneumaticity and anatomical (e.g., body size) or behavioral (e.g., diving) characteristics in some neognath birds. In some cases such patterns appear to represent clade-level features, characterizing clades within higher-level groupings. The only quantitative assessment of relative pneumaticity conducted to date examined anseriform birds. Hence, the degree to which such patterns can be generalized to other groups remains unclear. As an independent test of the anseriform dataset, 108 species of charadriiforms were examined in this study. Methods included both latex injection of the pulmonary system or direct examination of osteological specimens. The Pneumaticity Index (PI) was used to quantify and compare relative pneumaticity across species. Both historical and ahistorical approaches were used to assess the relationship between body size and relative pneumaticity. Similar to anseriforms, two notable patterns emerge: (1) pneumaticity in diving taxa (e.g., alcids) is reduced or absent relative to their nondiving sister group; and (2) although consistent patterns have been identified within a given subclade, these exhibit considerable variability relative to one another and suggest a substantial influence of phylogeny at lower taxonomic levels. Most striking is the significant, positive relationship between body size and relative pneumaticity in larids, with larger bodied forms characterized by higher PI values. Thus, repeated patterns of relative pneumaticity are indeed apparent in only distantly related neognath groups (anseriforms and charadriiforms) and underscore the extreme level of developmental plasticity at the interface between the pulmonary and skeletal systems in birds.
