A study explores the evolutionary origin and function of a small, toothless beak-like structure at the front of the toothed jaws of some prehistoric birds. The structure, termed a predentary, was seen in toothed ornithuromorph birds that lived in the Cretaceous, but is not found in modern birds. Alida M. Bailleul, Zhonghe Zhou, and colleagues investigated the origin and function of the predentary in the preserved remains of Yanornis martini from China, a small bird that consumed fish. The authors used high resolution CT scans and other microscopic analyses to develop a 3D model of the tip of the jaws and tissues. The authors found evidence of cartilage inside the joint between the predentary and the rest of the lower jaw. Together, the results suggest that the predentary was mobile and had characteristics of a sesamoid bone, which is embedded within soft tissues. Other characteristics suggest that the predentary and teeth were proprioceptive, which could have aided in prey capture by responding to sensory stimuli. According to the authors, the proprioceptive capability and kinetic movement of the predentary inferred from the results may have played a role in precision and dexterity during foraging.
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Article # 19-11820: "Origin of the avian predentary and evidence of a unique form of cranial kinesis in Cretaceous ornithuromorphs," by Alida M. Bailleul, Zhiheng Li, Jingmai O'Connor, and Zhonghe Zhou.
MEDIA CONTACT: Alida Bailleul, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, CHINA; e-mail: alida.bailleul@ivpp.ac.cn
Proceedings of the National Academy of Sciences