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The end Permian to Middle Triassic interval (∼252–242 Ma) witnessed the largest marine mass extinction and the most delayed recovery in the Phanerozoic. The nature and mechanism of these biotic and environmental changes remain unclear. This special issue focuses on the Triassic marine sediments in South China, which provide unique documentation of the collapse and recovery of marine ecosystems. Six papers focus on biotic changes and their ecological significance in Early and Middle Triassic times, documenting evidence from bivalves, marine reptiles, stromatolites, hybodontid teeth, vertebrate coprolites, and other putative fossils. Two papers study conodont biostratigraphy across the Permian-Triassic boundary (PTB) and Induan-Olenekian boundary. Two papers reconstruct the palaeoenvironments of the Early Triassic Chaohu Fauna and Middle Triassic Luoping Biota. Two further papers present new marine δ13C records and biomarker data and link them to volcanic eruptions in Early Triassic times. These new findings are important for understanding the co-evolution between biotic and environmental changes in the aftermath of Permian-Triassic boundary mass extinction. [ABSTRACT FROM AUTHOR]

The terrestrial Yanliao Biota in northeastern China represents a Jurassic biodiversity hotspot. Abundant and diverse fossils include the oldest known representatives of several groups of plants, invertebrates, and vertebrates that thrived in a forest ecosystem under a humid and warm climate. Since the early 21st century, discoveries associated with the Yanliao Biota have significantly improved our understanding of Jurassic terrestrial ecosystems. However, a robust chronostratigraphic framework is required to calibrate the biota with key evolutionary events and to improve understanding of possible links between evolution and tectonism. In this paper, we report novel 40Ar/39Ar ages for two tuff layers (161.4 ± 0.8 Ma and 161.6 ± 0.6 Ma) positioned directly above the less-studied but salamander fossil-rich beds in Reshuitang, near Lingyuan, Liaoning Province, China. These new age data improve knowledge of the timing of diversification of early salamanders. We also review all reported age data and summarize significant fossils from classic Yanliao outcrops. Our study indicates that the Reshuitang fossil beds were deposited slightly later than the well-known Daohugou fossil beds situated ∼15 km away in Inner Mongolia and somewhat earlier than the Linglongta fossil beds in western Liaoning Province. These findings advance understanding of the Jurassic world during an episode of pronounced climatic warming. • We provide detailed age calibration for the Jurassic Yanliao Biota. • Our study allows us to understand Jurassic terrestrial ecosystems. • A robust chrono-stratigraphy reconstructs the link between life and climate. [ABSTRACT FROM AUTHOR]

The Jehol Biota comprises significant fossils that help to elucidate the evolution of Early Cretaceous terrestrial ecosystems. In this paper, we provide three new zircon U Pb age constraints (124.3 ± 1.5 Ma, 124.9 ± 1.6 Ma, and 121.5 ± 1.4 Ma) from the base to the top of the Jiufengshan Formation (Xinganling Group) at the Naketa section in the north Great Xing'an Range of eastern Inner Mongolia, China, within a succession that contains the typical Eosestheria - Ephemeropsis trisetalis - Lycoptera davidi (EEL) assemblage of the Jehol Biota. Combined biostratigraphic and radio-isotopic dating suggests that the Jiufengshan Formation in the Naketa section corresponds to the upper part of the Yixian Formation and the lower part of the Jiufotang Formation, making it Barremian to earliest Aptian in age. Our findings allow us to test a widely accepted hypothesis about the migration and radiation of the Jehol Biota, and show that these organisms preserved within the lower part of the Jiufengshan Formation reached the Naketa area during the second and third evolutionary stages. The preservation of Jehol elements in the Naketa section provides valuable clues regarding the evolutionary history of the Jehol Biota and its spatiotemporal development. Furthermore, our study allows us to explore possible links between evolutionary processes and concurrent tectonism in the North China Craton, as the timing of this Jehol migration occurred when the tectonic setting changed from a compressional to an extensional regime. • We provide detailed fossil records and robust age for the far north Jehol outcrop. • This study refutes the widely accepted model for the Jehol migration. • Our results test the link between biological radiation and tectonic activity. [ABSTRACT FROM AUTHOR]

The Early Cretaceous Jehol Biota in northern China is a terrestrial lagerstätte that contains exceptionally-preserved fossils, including birds, dinosaurs, pterosaurs, mammals, insects, and flowering plants. The biota underwent three developmental phases, with relatively limited biodiversity in an early phase that rapidly diversified in a middle phase; however, the relationship between this biological radiation and climate remains uncertain. In this paper, we study fossils from the early-to-middle phases of the Jehol Biota preserved in the Lower Cretaceous (middle Valanginian-lower Barremian) Dabeigou and Dadianzi formations of Hebei Province to ascertain climatic impact on biotic evolution. The occurrence of a cool to warm climate turnover during the deposition of these strata is inferred based on a synthesis of geochemical and paleontological evidence. Palaeogeographic distribution of the middle phase of the biota is wider and positioned more southerly than that of the early phase, possibly indicating that the biota in the early and middle phases lived in boreal and temperate climate realms, respectively. Biotic diversity shows an increasing trend from the early phase to the middle phase of the Jehol Biota, closely coinciding with the cool to warm turnover of the climate. The body sizes of some taxa in the middle phase were significantly smaller than those in the early phase, which is also interpreted as a climatic effect. This study represents the first attempt to correlate the response of terrestrial evolution of the Jehol Biota to climate change, with a focus on Early Cretaceous paleotemperatures. • The Lower Cretaceous of northern Hebei record early-middle stages of Jehol Biota. • Climate change from cool to warm during early development of Jehol Biota. • Warming climate enabled the diversification of the Jehol Biota. [ABSTRACT FROM AUTHOR]

New fossil-bearing horizons at the Gezidong and Jiaxikou localities, eastern Inner Mongolia, referred to as the Moqi fossil bed, yield a diverse fossil assemblage coined herein as "Moqi Fauna". The Moqi Fauna provides important insights into the evolution of some vertebrate clades, such as frogs and salamanders, and their Early Cretaceous diversification. In this paper, we report an improved chronology of the Moqi fossil bed based on SIMS and high-precision CA-ID-IRMS U-Pb zircon analyses of three tuff samples from horizons that are interstratified with the fossil-bearing layer at two localities. The SIMS U-Pb dating method applied on zircons from three samples gave dates of 117.8 ± 0.9/1.5 Ma, 117.7 ± 1.0/1.5 Ma, and 118.3 ± 1.2/1.7 Ma, respectively. Two high-precision CA-ID-IRMS U-Pb weighted mean 206Pb/238U ages of, 119.20 ± 0.38/0.38/0.72 Ma and 118.67 ± 0.13/0.14/0.28 Ma were also obtained. These findings indicate the age of the Moqi Fauna is ca. 119.20 Ma to 118.67 Ma. Comparison of the Moqi Fauna with the well-known Jehol Biota, as well as the Fuxin Biota of a slightly younger age, suggests that the Moqi Fauna was a distinct fauna which shows a potential link with the Jehol Biota. • We report the exceptional "Moqi Fauna" in eastern Inner Mongolia, China. • The "Moqi Fauna" is characterized by new and diverse fossil assemblages. • Mesozoic frog and salamander preserved together. • The Moqi fossil-bearing bed is precisely dated to 119.20–118.67 Ma. • Our study allows to better understand the vertebrate evolution and Early Cretaceous terrestrial ecosystem. [ABSTRACT FROM AUTHOR]