The existing time of Sihetun vertebrate in western Liao- ning, China---Evidence from U-Pb dating of zircon

In different opinions, the stratigraphic time of the feathered dinosaurs and early birds in Sihetun and its neighboring areas in Beipiao, western Liaoning is appointed to different epoches of eras, such as Late Jurassic, Early Cretaceous and Late Jurassic-Early Cretaceous. Even the recently dating data are still very different. This note first reported the U-Pb age of (125.2±0.9) Ma of zircon separated from tuff of Sihetun vertebrates horizon. The age reveals that Sihetun vertebrate belongs to Early Cretaceous. The method is more objective, because of the strong ability of disturbance resistance and high U-Pb blocking temperature of zircons.