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Contributed by Zhonghe Zhou, August 3, 2011 (sent for review July 13, 2011)
Abstract
The crop is characteristic of seed-eating birds today, yet little is known about its early history despite remarkable discoveries of many Mesozoic seed-eating birds in the past decade. Here we report the discovery of some early fossil evidence for the presence of a crop in birds. Two Early Cretaceous birds, the basal ornithurine Hongshanornis and a basal avian Sapeornis, demonstrate that an essentially modern avian digestive system formed early in avian evolution. The discovery of a crop in two phylogenetically remote lineages of Early Cretaceous birds and its absence in most intervening forms indicates that it was independently acquired as a specialized seed-eating adaptation. Finally, the reduction or loss of teeth in the forms showing seed-filled crops suggests that granivory was possibly one of the factors that resulted in the reduction of teeth in early birds.
Footnotes
- ↵1To whom correspondence should be addressed. E-mail: zhouzhonghe{at}ivpp.ac.cn.
Author contributions: X.Z., L.D.M., and Z.Z. designed research; X.Z., L.D.M., Z.Z., and D.M. performed research; X.Z., D.A.B., and F.Z. contributed new reagents/analytic tools; D.A.B. and F.Z. analyzed data; and L.D.M., Z.Z., and D.M. wrote the paper.
The authors declare no conflict of interest.
- Xiaoting Zhenga,b,
- Larry D. Martinc,
- Zhonghe Zhoud,1,
- David A. Burnhamc,
- Fucheng Zhangd, and
- Desui Miaoc
- aInstitute of Geology and Paleontology, Linyi University, Linyi, Shandong 276000, China;
- bShandong Tianyu Museum of Nature, Pingyi, Shandong 273300, China;
- cDivision of Vertebrate Paleontology, Biodiversity Institute, University of Kansas, Lawrence, KS 66045;
- dKey Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China
Contributed by Zhonghe Zhou, August 3, 2011 (sent for review July 13, 2011)
Abstract
The crop is characteristic of seed-eating birds today, yet little is known about its early history despite remarkable discoveries of many Mesozoic seed-eating birds in the past decade. Here we report the discovery of some early fossil evidence for the presence of a crop in birds. Two Early Cretaceous birds, the basal ornithurine Hongshanornis and a basal avian Sapeornis, demonstrate that an essentially modern avian digestive system formed early in avian evolution. The discovery of a crop in two phylogenetically remote lineages of Early Cretaceous birds and its absence in most intervening forms indicates that it was independently acquired as a specialized seed-eating adaptation. Finally, the reduction or loss of teeth in the forms showing seed-filled crops suggests that granivory was possibly one of the factors that resulted in the reduction of teeth in early birds.
- paleornithology
- feeding
Footnotes
- ↵1To whom correspondence should be addressed. E-mail: zhouzhonghe{at}ivpp.ac.cn.
Author contributions: X.Z., L.D.M., and Z.Z. designed research; X.Z., L.D.M., Z.Z., and D.M. performed research; X.Z., D.A.B., and F.Z. contributed new reagents/analytic tools; D.A.B. and F.Z. analyzed data; and L.D.M., Z.Z., and D.M. wrote the paper.
The authors declare no conflict of interest.
Fossil evidence of avian crops from the Early Cretaceous of China
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