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

In different opinions, the stratigraphic time of the feathered dinosaurs an d early birds in Sihetun and its neighboring areas in Beipiao, western Liao ning is appointed to different epoches of eras, such as Late Jurassic, Earl y Cretaceous and Late Jurassic-Early Cretaceous. Even the recently dating d ata 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 resi stance and high U-Pb blocking temperature of zircons.