High‐Altitude and Cold Habitat for the Early Cretaceous Feathered Dinosaurs at Sihetun, Western Liaoning, China.

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]