Researchers report a small fossil reptile related to dinosaurs and pterosaurs that suggests a miniaturized origin for some of the largest animals to live on Earth. Dinosaurs and pterosaurs, known for being among the largest land-dwelling and flying animals in Earth's history, belong to the group Ornithodira. Their origins, however, are poorly understood, given that few specimens from the root of this lineage have been found. Christian F. Kammerer and colleagues report an early ornithodiran named Kongonaphon kely, discovered in Mid-to-Upper Triassic rocks in Madagascar. In contrast to the large size of many of its dinosaur and pterosaur relatives, Kongonaphon would have stood only around 10 cm tall. Analysis of ornithodiran body size evolution suggests that the dinosaur and pterosaur lineages originated from extremely small ancestors, carrying important implications for their paleobiology. Wear on the conical teeth of Kongonaphon suggests a diet of insects, and a shift to insectivory associated with small body size may have helped early ornithodirans occupy ecological niches distinct from co-occurring reptiles. Heat retention in small bodies is difficult, and the Triassic was a time of climatic extremes. Hence, fuzzy skin coverings ranging from simple filaments to feathers, which are known on both the dinosaur and pterosaur sides of the ornithodiran tree, may have originated for thermoregulation in small-bodied common ancestors, according to the authors.
Article #19-16631: "A tiny ornithodiran archosaur from the Triassic of Madagascar and the role of miniaturization in dinosaur and pterosaur ancestry," by Christian F. Kammerer, Sterling J. Nesbitt, John J. Flynn, Lovasoa Ranivoharimanana, and André R. Wyss.
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Proceedings of the National Academy of Sciences