Characterization of keratin thickness and beak dimensions (relative to beak length) in the different functional groups.

Table entries are means ± standard deviations. Characterization of keratin thickness and beak dimensions (relative to beak length) in the different functional groups.表格内的数值均为平均值±标准差。不同功能类群的角蛋白（keratin）厚度及喙部尺寸（以喙长为参照）的特征表征。