Developmental strategies underlying gigantism and miniaturization in non-avialan theropod dinosaurs

In amniotes, the predominant developmental strategy underlying body size evolution is thought to be adjustments to the rate of growth rather than its duration. However, most theoretical and experimental studies supporting this axiom focus on pairwise comparisons and/or lack an explicit phylogenetic framework. We present the first large-scale phylogenetic comparative analysis examining developmental strategies underlying the evolution of body size, focusing on non-avialan theropod dinosaurs. We reconstruct ancestral states of growth rate and body mass in a taxonomically rich dataset, finding that contrary to expectations, changes in the rate and duration of growth played nearly equal roles in the evolution of the vast body size disparity present in non-avialan theropods-and perhaps that of amniotes in general.

Automated summary

In amniotes, adjustments to the rate of growth rather than its duration are considered as the primary developmental strategy underlying body size evolution. However, most previous studies lack a phylogenetic framework and focus on pairwise comparisons. Here, we present a large-scale phylogenetic comparative analysis of non-avialan theropod dinosaurs, revealing that changes in both growth rate and duration played significant roles in the evolution of body size disparity in these dinosaurs and potentially in amniotes as a whole.