Wing‐bone length allometry in birds

A comparative analysis using both independent contrasts (CAIC) and a species level analysis was used to investigate the allometric scaling of avian wing‐bone lengths. Total arm ( ta =humerus+ulna+manus) scaled with positive allometry as body mass ( M ) 0.37–0.39 . Similarly, and in accordance with previous studies, wing‐span ( b ) was positively allometric, but CAIC suggested a lower allometric exponent ( M 0.35 ) than found using species as independent data points ( M 0.39 ). Contrary to previous studies, individual wing‐bones appear to scale with similar exponents against M and scale isometrically with ta . In addition to a general trend for larger birds to have longer wings, wing‐bones and ta , their ta was a larger proportion of their b . A detailed study of primary feather length and elbow joint angle across a wide range of bird species and bird size, however, is required before a conclusive explanation for this increase in ta relative to b in larger birds can be established. Scaling equations are presented that can be used to predict M , ta and b from individual wing‐bone lengths, which may be of use to palaeontologists wishing to reconstruct whole animals from single bones.