Chronological evidence for extension of the Jehol Biota into Southern China

The fossils of the Cretaceous Jehol Biota are magnificent, exquisitely preserved and extraordinarily diverse. Strata that may be correlative with the classic Jehol localities are known over much of Central and Eastern China, as well as Korea, Japan, Mongolia and Siberia. It has been previously hypothesized based on fossil assemblages that the Jehol Biota progressively expanded from the classic Jehol area, with younger representatives covering progressively larger geographic ranges. It has been interpreted that the youngest Jehol Biota bearing layers are in the East Anhui province of South China. Here we present robust 40Ar/39Ar dates of 129.0 ± 0.2 Ma for one rhyolite sample from the lower Longwanshan Formation and 127.1 ± 1.3 Ma and 128.0 ± 0.9 Ma for two volcanic samples from the upper Honghuaqiao Formation from the outcrops of Jehol fossils in East Anhui. Our age results indicate that fossils from these formations are time-equivalent to the second phase fossils from the lower Yixian Formation in the western Liaoning, NE China, and the deposition of these beds is at least 6 Ma older than previously estimated. Therefore our results suggest that the hypothesis of the Jehol radiation and migration should be reevaluated.