Estimating body weight and habitat type from extinct avian and avian-like theropod footprints

Abstract

The relationship between body weight and footprint area of modern avians was derived and used to estimate the body weights of non-avian theropods taxa from the Triassic to Cretaceous and extinct avian taxa from the Cretaceous periods. Geometric information, such as the area and shape of fossil tracks of extinct avians and non-avian theropods, was used to estimate body weight and habitat type. The percentage prediction and standard error of estimates indicated that the body weight estimated from track area is comparable with body weight estimated from body fossils bones. Therefore, this approach is useful when the fossilized track record is richer than the fossilized skeletal record. The data sets for avians and reptiles were combined and used to derive a body weight–area relationship that may be applicable to a broader range of organisms, such as plantigrade quadrupeds and digitigrade bipeds. Additionally, scatter plots of the relationship between habitat type and footprint shape of modern avians were used to infer the habitat type of extinct avians. This finding suggests that the pes of animals, living in areas characterized by fluctuating water levels, and under conditions facilitating the preservation of footprints, were similar in form to those of extant semi-aquatic avians.