SIMS U-Pb geochronology for the Jurassic Yanliao Biota from Bawanggou section, Qinglong (northern Hebei Province, China)

ABSTRACT

The Yanliao Biota is notable for producing rare and well-preserved Jurassic vertebrate fossils. Many discoveries in the Bawanggou section, northern Hebei Province have greatly enhanced our knowledge of important vertebrate fossils from the Yanliao Biota, including an arboreal euharamiyidan mammal, maniraptoran theropods, salamanders and pterosaurs. However, lacking of precise dating for the sediments bearing these fossils in the Bawanggou section hampered further understanding of the evolution of this biota. Here we report a chronology based on secondary ion mass spectrometry (SIMS) U-Pb zircon analyses from the Tiaojishan Formation bearing the Yanliao Biota in the Bawanggou section. Three bentonite layers dated to 159.0 ± 1.1 Ma, 159.5 ± 0.8 Ma, and 159.8 ± 0.8 Ma, respectively, were found to be interstratified with the fossil-bearing layer in this area. These data place the Yanliao Biota from Qinglong in the Oxfordian Stage of the Upper Jurassic and provide stringent constraints on vertebrates discovered in the Bawanggou section. Previous biostratigraphic studies and our geochronology show that fossil assemblage in the Bawanggou section is coeval with the Linglongta Biota (late Yanliao Biota) preserved in the Daxishan section (western Liaoning Province).

KEYWORDS:

• Late Jurassic
• Yanliao Biota
• Bawanggou section
• SIMS U-Pb geochronology

Acknowledgments

We thank the Editor Robert Stern, and two reviewers (Prof. Diying Huang and anonymous reviewer) for their insightful comments and suggestions, to improve the manuscript. This work was supported by the National Natural Science Foundation of China (grants 41688103, 41425013 and 41972007), and the Strategic Priority Research Program of the Chinese Academy of Sciences. This paper is a contribution to the IGCP Project 679.

Disclosure statement

No potential conflict of interest was reported by the authors.

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Funding

This work was supported by the National Nature Science Foundation of China [Grant Nos. 41688103, 41425013 and 41972007]; the Strategic Priority Research Program (B) of the Chinese Academy of Sciences [Grant Nos. XDB18030505 and XDB26000000].