Fossil evidence sheds light on sexual selection during the early evolution of birds

• 成果类型: Article
• 署名作者: Zhou, Yibo; Pan, Yanhong; Wang, Min; Wang, Xiaoli; Zheng, Xiaoting; Zhou, Zhonghe
• 署名单位: Nanjing University; Nanjing University; Chinese Academy of Sciences; Institute of Vertebrate Paleontology & Paleoanthropology, CAS; Linyi University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-14475
• DOI: 10.1073/pnas.2309825120
• 发表日期: 2024-01-16
• 关键词: tufted malachite sunbird; male mating success; size dimorphism; body-size; tail ornamentation; shape dimorphism; female choice; confuciusornis; allometry; length

摘要

The impact of sexual selection on the evolution of birds has been widely acknowledged. Although sexual selection has been hypothesized as a driving force in the occurrences of numerous morphological features across theropod evolution, this hypothesis has yet to be comprehensively tested due to challenges in identifying the sex of fossils and by the limited sample size. Confuciusornis sanctus is arguably the best-known early avialan and is represented by thousands of well-preserved specimens from the Early Cretaceous Jehol lagerstatte, which provides us with a chance to decipher the strength of sexual selection on extinct vertebrates. Herein, we present a morphometric study of C. sanctus based on the largest sample size of this taxon collected up to now. Our results indicate that the characteristic elongated paired rectrices is a sexually dimorphic trait and statistically robust inferences of the sexual dimorphism in size, shape, and allometry that have been established, providing the earliest known sexual dimorphism in avian evolution. Our findings suggest that sexual selection, in conjunction with natural selection, does act upon body size and limb length ratio in early birds, thereby promoting a deeper understanding of the role of sexual selection in large-scale phylogenetic evolution.