image: Archaeorhynchus specimen displaying preserved plumage and lung tissue. view more
Credit: Image courtesy of J. Zhang (Institute of Vertebrate Paleontology and Paleoanthropology, Beijing).
Researchers report evidence of fossilized lung structures in an early bird that reveals structural similarities with modern birds. Evolutionary developments that supported flight include unidirectional airflow in the lungs, supplementary air sacs, and lung tissue that is finely subdivided to maximize surface area. Extant in living crocodilians, unidirectional airflow is now considered ancestral to early feathered dinosaurs, but fossilized lung structures in early bird and dinosaur lineages had not previously been found. Zhonghe Zhou, Jingmai O'Connor, and colleagues analyzed a specimen of Archaeorhynchus spathula, an early bird that lived during the Cretaceous Period, via scanning electron microscopy. The authors focused on a speckly white material in the chest cavity not previously seen in Archaeorhynchus or any other fossil. The results of the fossil analysis revealed an extremely subdivided structure similar to that of modern bird lungs, which enables the high oxygen diffusion capacities necessary for powered flight. The authors also found in the preserved plumage a pintail feather structure not shared by other known Cretaceous birds but common in modern specimens. According to the authors, the results suggest that key avian structures were in place by the Early Cretaceous and may have helped modern bird ancestors survive the extinction of the dinosaurs.
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Article #18-05803: "Archaeorhynchus preserving significant soft tissue including probable fossilized lungs," by Xiaoli Wang et al.
MEDIA CONTACT: Zhonghe Zhou, Institute of Vertebrate Paleontology and Paleoanthropology, Beijing, CHINA; e-mail: zhouzhonghe@ivpp.ac.cn; Jingmai O'Connor, Institute of Vertebrate Paleontology and Paleoanthropology, Beijing, CHINA; e-mail: jingmai@ivpp.ac.cn
Journal
Proceedings of the National Academy of Sciences