Dinosaur-like forms in early bird shoulders

Researchers report a species of early bird with a combination of bird-like and dinosaur-like bone morphologies. Early members of the Pygostylia, birds with short tails that end in a compound bone, are critical for understanding how the body plan of modern birds evolved. Min Wang, Thomas A. Stidham, and Zhonghe Zhou describe a specimen of Pygostylia named Jinguofortis perplexus from the Early Cretaceous Period in China that forms, along with the bird Chongmingia, an evolutionary branch, or clade, named Jinguofortisidae, the second-earliest known branch of Pygostylia. Jinguofortisids display a mosaic of characteristics, some reminiscent of nonavian theropod dinosaurs and others uniquely evolved in birds and specialized for flight, including a reduction in hand digits. Of note among the theropod-like features is a fused scapula and coracoid as part of the shoulder assembly. The authors report that the fusion of the scapulocoracoid may result from accelerated bone ossification, which may have helped the birds rapidly achieve maturity. With short, wide wings, Jinguofortis may have lived in dense forests. According to the authors, the structure of the shoulder girdle, when considered in context with the structures of other major four-footed animal groups, highlights the role of developmental plasticity in the early evolution of birds.

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Article #18-12176: "A new clade of basal Early Cretaceous pygostylian birds and developmental plasticity of the avian shoulder girdle," by Min Wang, Thomas A. Stidham, and Zhonghe Zhou.

MEDIA CONTACT: Min Wang, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, CHINA;; e-mail: wangmin@ivpp.ac.cn; Zhonghe Zhou, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, CHINA;; e-mail: zhouzhonghe@ivpp.ac.cn

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