New research on dinosaurs: bird flapping flight or multiple independent origins

 New research on dinosaurs: bird flapping flight or multiple independent origins

Wing load and takeoff power of small theropod dinosaurs. (photo provided by research team)

The reporter learned from the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, that Xu Xings team led by the Institute and researchers from the University of Hong Kong, Argentina, the United States and the United Kingdom systematically analyzed and updated the phylogenetic tree of Xugu dinosaurs using the implicit weight method. On this basis, quantitative analysis showed that flapping wing flight may have occurred three times or more in near bird dinosaurs This important achievement has been published online in the international academic journal contemporary biology.

Pei Rui, a member of the research team and co first author of the paper, introduced that the evolutionary history of the Mesozoic small theropod dinosaurs had multiple evolutionary convergence phenomena, resulting in some uncertainty in the phylogenetic analysis results. As a framework for exploring evolutionary problems, the uncertainty of phylogeny limits the accurate analysis of the evolutionary history of morphological functions such as the origin of bird flight.

On the basis of expanding the evolution matrix of the virtual skeleton dinosaurs, this study uses the implicit weight method for the morphological features in the system analysis, and gives weights to different features to reduce the uncertainty of the analysis results caused by evolutionary convergence. The results of this systematic analysis re support the monophyletic dinoflagellates, which are composed of chilosauridae and traumatosauridae, while the near ornithosaurs are at the base of ornithoptera. The trosaurus members of the early Cretaceous Jehol biota of China and the Western clawed dinosaurs of North America are classified into the monophyletic microraptors.

Based on the newly established phylogenetic tree, he said, the team conducted a quantitative analysis of the dynamic flapping flight potential of early winged ornithoptera and closely related birds. In this study, wing load and takeoff power were selected to estimate and reconstruct the fossil species and ancestral nodes.

The results show that most of the early ornithoptera and some non bird dinosaurs (Microraptor and ornithosaur) have reached the reference value standard of wing load and take-off power of present-day flying birds, that is, they have the potential of dynamic flapping wing flight. In addition, the wing load of some small non bird dinosaurs reached the reference value of living flying birds, but the take-off power was insufficient, and the other groups, including the larger theropod dinosaurs, did not meet the standard of living flying birds.

According to Pei Rui, the latest research supports the multiple independent flapping wing flight origins of theropods. Besides ornithoptera, at least two possible flight origin events have been identified, and the wing load and take-off power of a series of non bird dinosaurs are close to the reference values of living birds. The results suggest that while birds initially took off, many non ornithopod dinosaurs may have been exploring a biplane assisted movement pattern, and some of them have successfully flapped their wings and flew to the sky. However, the specific details and patterns of the independent origins of these flights need to be further studied.

Source: Wang Fengzhi, editor in charge of China News Network_ NT2541