Evolution of body mass in the Pan-Alcidae (Aves, Charadriiformes): the effects of combining neontological and paleontological data

Hypotheses regarding the evolution of many clades are often generated in the absence of data from the fossil record and potential biases introduced by exclusion of paleontological data are frequently ignored. With regard to body size evolution, extinct taxa are frequently excluded because of the lack of body mass estimates—making identification of reliable clade specific body mass estimators crucial to evaluating trends on paleontological timescales. Herein, I identify optimal osteological dimensions for estimating body mass in extinct species of Pan-Alcidae (Aves, Charadriiformes) and utilize newly generated estimates of body mass to demonstrate that the combination of neontological and paleontological data produces results that conflict with hypotheses generated when extant species data are analyzed in isolation. The wing-propelled diving Pan-Alcidae are an ideal candidate for comparing estimates of body mass evolution based only on extant taxa with estimates generated including fossi...