The potential of fossil primary feather in taxonomic and ecological prediction

Abstract

Feathers, shaped by the interplay of phylogenetic factors and environmental behaviors, serve not only as critical indicators for avian classification but also as carriers of information regarding flight patterns and ecological habitats. Although isolated fossil feathers are frequently undervalued due to the lack of direct skeletal associations, their well-preserved outline and microstructure can provide critical insights into key issues such as feather evolution, the origin of flight behavior, and taxonomic diversity. In this study, we discovered an exceptionally well-preserved distal primary feather from the Lower Cretaceous in the Jiuquan Basin of northwest China. We extracted the morphological outlines of modern primary feathers for elliptic Fourier analysis and combined microstructural data to test whether feather morphology can be used to distinguish taxonomic groups, orders, and habitats. The results indicate that the flight feather morphology in modern birds is predominantly shaped by flight-related adaptations, with significant morphospace differentiation across flight types and taxonomic orders, while habitat exerts minimal influence on feather architecture. Furthermore, multivariate statistical analyses that incorporate fossil data into modern datasets suggest that the primary feather fossil occupies a morphospace position associated with terrestrial ecological and flight mode similar to that of modern passerine type, indicating a potential association between the fossil feather and enantiornithines. However, accurate identification of fossil feather information requires expanded fossil data collection to uncover further insights embedded within the fossilized feathers.