A new paper with free pdf (for now):
Highlights
Among Aves, molt strategy is correlated with habitat selection and flight ability
An ancestral feather molt strategy for Aves is probably sequential
Microraptor is the earliest known feathered vertebrate with a sequential wing molt
Microraptor likely maintained its flight ability throughout the entire year
Summary
Feather molt 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 molt, a common strategy among extant birds, identified in the Early Cretaceous four-winged dromaeosaurid Microraptor. Analysis of wing feather molt patterns and ecological properties in extant birds imply that Microraptor maintained its flight ability throughout the entire annual cycle, including the molt 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 molt is the outcome of evolutionary forces to maintain flight capability throughout the entire annual cycle in both extant birds and non-avialan paravian dinosaurs from 120 mya.