Fossilized skin reveals coevolution with feathers and metabolism in feathered dinosaurs and early birds

Maria E Mcnamara,Zhonghe Zhou,David W E Hone,Michael J Benton,Fucheng Zhang,André Toulouse,Xing Xu,Diane Johnson,Tara Foley,Stuart L Kearns,Chris S Rogers,Patrick J Orr

doi:10.1038/s41467-018-04443-x

Abstract

Feathers are remarkable evolutionary innovations that are associated with complex adaptations of the skin in modern birds. Fossilised feathers in non-avian dinosaurs and basal birds provide insights into feather evolution, but how associated integumentary adaptations evolved is unclear. Here we report the discovery of fossil skin, preserved with remarkable nanoscale fidelity, in three non-avian maniraptoran dinosaurs and a basal bird from the Cretaceous Jehol biota (China). The skin comprises patches of desquamating epidermal corneocytes that preserve a cytoskeletal array of helically coiled α-keratin tonofibrils. This structure confirms that basal birds and non-avian dinosaurs shed small epidermal flakes as in modern mammals and birds, but structural differences imply that these Cretaceous taxa had lower body heat production than modern birds. Feathered epidermis acquired many, but not all, anatomically modern attributes close to the base of the Maniraptora by the Middle Jurassic.

Highlights

Feathers are remarkable evolutionary innovations that are associated with complex adaptations of the skin in modern birds
Evo-devo studies[4] and fossilised feathers[5,6,7] have illuminated aspects of early feather evolution, but how the skin of basal birds and feathered nonavian dinosaurs evolved in tandem with feathers has received little attention
We report the discovery of fossilised skin in the feathered non-avian maniraptoran dinosaurs Beipiaosaurus, Sinornithosaurus and Microraptor, and the bird Confuciusornis from the Early Cretaceous Jehol biota (NE China; Supplementary Fig. 1)

Summary

Introduction

Feathers are remarkable evolutionary innovations that are associated with complex adaptations of the skin in modern birds. We report the discovery of fossilised skin in the feathered non-avian maniraptoran dinosaurs Beipiaosaurus, Sinornithosaurus and Microraptor, and the bird Confuciusornis from the Early Cretaceous Jehol biota (NE China; Supplementary Fig. 1).

Results

Conclusion