Earliest evidence of avian primary feather moult (1 Viewer)

[Fred Ruhe]

Xiaoli Wang, Jingmai O’Connor, Xiaoting Zheng ,Yan Wang and
Yosef Kiat4/ 2024

Earliest evidence of avian primary feather moult

Biology Letters. 20 (7). 20240106. doi:10.1098/rsbl.2024.0106. PMID 38955226.

Abstract: https://royalsocietypublishing.org/doi/10.1098/rsbl.2024.0106

Feather moulting is a crucial process in the avian life cycle, which evolved to maintain plumage functionality. However, moulting involves both energetic and functional costs. During moulting, plumage function temporarily decreases between the shedding of old feathers and the full growth of new ones. In flying taxa, a gradual and sequential replacement of flight feathers evolved to maintain aerodynamic capabilities during the moulting period. Little is known about the moult strategies of non-avian pennaraptoran dinosaurs and stem birds, before the emergence of crown lineage. Here, we report on two Early Cretaceous pygostylian birds from the Yixian Formation (125 mya), probably referable to Confuciusornithiformes, exhibiting morphological characteristics that suggest a gradual and sequential moult of wing flight feathers. Short primary feathers interpreted as immature are symmetrically present on both wings, as is typical among extant flying birds. Our survey of the enormous collection of the Tianyu Museum confirms previous findings that evidence of active moult in non-neornithine pennaraptorans is rare and likely indicates a moult cycle greater than one year. Documenting moult in Mesozoic feathered dinosaurs is critical for understanding their ecology, locomotor ability and the evolution of this important life-history process in birds.

Enjoy,

Fred

 

[Fred Ruhe]

Figure 1. Gradual and sequential moult. An example of a typical primary moult among flying taxa. This moult strategy includes a limited and temporary moultrelated gap in the wing-feathered surface (white-throated robin, Irania gutturalis). The coloured areas in the small wing (bottom right) represent different plumage
parts: old and abraded primary feathers (light blue), new or growing primary feathers (dark blue), secondary feathers (yellow), tertials (orange), wing coverts (grey) and alula (green).


Figure 2. Primary feather moult in early pygostylian birds, (a) STM7-21, and (b) STM7-22. The black arrows indicate the growing feathers and the moult-related wing gap. The coloured areas represent different plumage parts: primary feathers (light blue), growing primary feathers (dark blue), secondary feathers (yellow) and rectrices (green).


Fred