Sequential Moult in a Feathered Dinosaur: Implications for Early Paravian Locomotion and Ecology

Abstract

Feather moult is an important life-history process in birds, but little is known about its evolutionary history. Here we report on the first fossilized evidence of sequential wing feather moult, a common strategy among extant birds, identified in the Early Cretaceous four-winged dromaeosaurid Microraptor. Analysis of wing feather moult patterns and ecological properties in extant birds imply that Microraptor maintained its flight ability throughout the entire annual cycle, including the moult period. Therefore, we conclude that flight was essential for either its daily foraging or escaping from predators. Our findings propose that the development of sequential moult is the outcome of evolutionary forces to maintaining flight capability throughout the entire annual cycle in both extant birds and non-avialan paravian dinosaurs from 120 million years ago.