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During the Early Cretaceous, significant tectonic regime transformation occurred in East China. Meanwhile, the Jehol Biota, which contains world‐famous feathered dinosaurs, flourished. However, few studies have been conducted to investigate the influence of tectonic regime transformation on regional topography and climates and the possible climatic causes of the unique characteristics of these dinosaurs. Here, we address these issues by applying clumped isotope paleothermometry to Early Cretaceous carbonates in NE China. In the Sihetun area, the mean annual paleotemperature derived from paleosol carbonates was 5.9 ± 1.7°C, and the paleoelevation was 2.8–4.1 km during the Early Cretaceous. The topographic evolution was closely related to the subduction of the paleo‐Pacific plate beneath East Asia during this period. Our results suggest a high altitude and cold habitat with frozen winters for the Jehol Biota in the Sihetun area, which implies possible climate‐Keywords:influenced evolution of the feathered characteristic of the dinosaurs. Plain Language Summary: During the Early Cretaceous, the Jehol Biota, especially the unique feathered dinosaurs, flourished in western Liaoning Province, China. As insulation devices, the feathers helped these nonavian dinosaurs resist the cold climate, although conventional opinions have suggested that the Early Cretaceous was a typical "greenhouse climate" world. Based on the clumped isotopes of the paleosol carbonates in the Sihetun area, our study estimates the paleotemperature and paleoaltitude of the living habitat of these feathered dinosaurs during the Early Cretaceous. We suggest that the feathered dinosaurs in NE China lived in a high‐altitude habitat with frozen winters and volcanic eruptions, which implies possible climate‐influenced evolution of the feathered characteristic of the dinosaurs. We also suggest that topographic change‐induced cooling was caused by significant tectonic regime transformation in East China. Key Points: We analyze carbonate clumped isotopes to estimate the Early Cretaceous elevation of the habitat of feathered dinosaurs in NE ChinaThe feathered dinosaurs lived in a high‐altitude habitat with freezing conditions in winter in NE China during the Early CretaceousTopographic changes were caused by the eastward subduction of the paleo‐Pacific plate [ABSTRACT FROM AUTHOR]

The Lower Cretaceous Yixian Formation in western Liaoning, China contains the exceptionally well-preserved Jehol Biota, and includes the famous assemblages known as "Dinosaur Pompeii". In this study, we focus on the fossil-rich Zhuanchengzi Bed near Yingwoshan, and describe laminated lacustrine successions that show prominent rhythmites to understand subdecadal palaeoclimate variability. We highlight the cyclicity preserved at a millimetre-scale based on analysis of the rhythmic alterations between the light- and dark-coloured carbonate-siliciclastic layers. Coupling petrographic with phase-specific geochemical analyses, we infer these laminated successions represent varves. The light-coloured layers of the couplets, containing dolomite-dominated carbonates, developed during warm seasons as a result of chemical precipitation enhanced by photosynthetic activities and rhythmic changes in the ambient water properties. The dark-coloured layers are mostly composed of siliciclastic and clay minerals representing terrestrial input during cold seasons. Varve thickness variations likely record seasonal climate changes regulated by ancient Asian Monsoons and decade-level cyclicities, such as ENSO-like and solar cycles. Overall, the varve records in the Yixian Formation offer a novel perspective on the palaeoseasonality of the Jehol Biota and provide insights into the dominant climate mode over interannual time scales of the Early Cretaceous greenhouse world. • Dolostones from Yixian Formation in Jehol Biota show clear annual laminations. • The light- and dark-coloured layers precipitated in wet and dry seasons of a year. • Seasonal variations of precipitation and temperature existed in the Early Cretaceous. • Early Cretaceous solar cycles and ENSO-like signals are preserved in varves. [ABSTRACT FROM AUTHOR]