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Thick successions of middle and late Cenozoic sedimentary rocks occur in the Linxia Basin of China. These deposits comprise an archive recording spatiotemporal patterns of mountain uplift, erosion, basin deformation, and associated changes in the monsoon, as a result of the growth of the northeastern Tibetan Plateau. The Linxia Basin is also world famous for its abundant and diverse vertebrate fossils that shed light on Cenozoic terrestrial ecosystem evolution; however, previous studies of these important fossils have been beset by issues related to commercial excavation and associated difficulties in ascertaining provenance, with many specimens in private collections. Despite years of intensive studies by geologists from Lanzhou University and vertebrate paleontologists from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP), aspects of basin stratigraphy and chronology still remain controversial. The heart of these controversies often revolves around questions of imprecise fossil provenance and related casual references of fossils as age tie-points, different interpretations of lithostratigraphic units at different localities across the basin, and ultimately different age determinations. In this special issue, entitled Biostratigraphy, Chronostratigraphy and Vertebrate Paleontology of the Linxia Basin, we report the findings of an IVPP project, funded by the Chinese Academy of Sciences, which addresses these controversies, proposes a new age model for basin, and develops understanding of the fossil assemblages. In this introduction to the special issue, we review the tectonic context for basin evolution and chronology as well as lithostratigraphy, paleoenvironments and climates. While issues of provenance remain challenging and will continue to burden Chinese vertebrate paleontologists into the future, our findings shed new light on the vertebrate paleontology of the Linxia Basin, and unique circumstances in which it developed.

Establishing the temporal sequence of the Middle-Late Jurassic Yanliao Biota is essential as it anchors the timing of many key evolutionary innovations in vertebrates. Lack of sufficiently reliable high-precision ages of fossil-bearing horizons hinders our ability to reconstruct the tempo and mode of vertebrate evolution. Here, we frame a temporal sequence of Yanliao Biota with precise age constraints for iconic vertebrates, proposing that the major vertebrate-bearing strata span from 164 Ma to 157 Ma in age. The increasing ecological diversity of mammaliaforms is well illustrated by the Middle-Late Jurassic Yanliao Biota and Early Cretaceous Jehol Biota. Incorporation of the updated temporal frameworks in Bayesian tip-dated mammaliaform phylogeny reveals that Triassic haramiyidans are separate from Jurassic taxa and unrelated to crown Mammalia. Tip-dated phylogeny supports a long-fuse model for mammal evolution, featured by a Late Triassic root and Middle-Late Jurassic interordinal diversification of crown Mammalia, showing consistency with molecular-based timetrees in divergence timing.

Archeomagnetism focuses on exploring high-resolution variations of the geomagnetic field over hundreds to thousands of years. In this study, we carried out a comprehensive study of chronology, absolute and relative paleointensity on a late Neolithic site in central China. Ages of the samples are constrained to be ~3,500–3,000 BCE, a period when available paleointensity data are sparse. We present a total of 64 high-fidelity absolute paleointensities, demonstrating the field varied quickly from ~55 to ~90 ZAm2 between ~3,500–3,000 BCE. Our results record a new archeomagnetic jerk around 3,300 BCE, which is probably non-dipolar origin. The new results provide robust constraints on global geomagnetic models. We calculated a revised Chinese archeointensity reference curve for future application. The variations of absolute and relative paleointensity versus depth show good consistency, reinforcing the reliability of our results. This new attempt of combining absolute and relative paleointenstiy provides a useful tool for future archeomagnetic research.

The Aoerban region of central Inner Mongolia, China is an important early Miocene fossil site that contains a diverse mammalian record unrivaled by other Asian sites of similar age. In this paper, we present lithostratigraphic, biostratigraphic, and magnetostratigraphic data from Aoerban Formation to better understand faunal changes between the Xiejian and Shanwangian Chinese Land Mammal ages. With new biochronological constraints, magnetochrons in the Aoerban Formation can be correlated to C6An.2n to C5Cr with an age range of 20.71–16.72 Ma of the Astronomically Tuned Neogene Timescale (ATNTS2012). The strata of the Aoerban region contain a number of important mammalian First Appearance Data, including several morphotypes of deer (Cervidae), horses (Anchitherium), pika (Alloptox), cricetid rodents (Megacricetodon), and possibly the local earliest record of gomphotheres (i.e., the Proboscidea event). Although the ranges for most of these taxa are still poorly known, some of them, alone or in combination, are useful in defining the base the Shanwangian Land Mammal Age. Within this finely calibrated chronologic framework, the faunas of the Aoerban region are important for better understanding mammalian evolution, biogeography, and paleoenvironment.

Detailed understanding to the evolution of Neogene land mammals in East Asia and its intercontinental correlation has been impeded by the absence of an integrated biochronological system of this region. The numerous and diverse records of Neogene vertebrate fossils preserved in Inner Mongolia of northern China play a key role in the establishment of an independent biochronological framework in East Asia. However, most of these faunas are poorly constrained by independent chronological controls due to the scattered distribution of fossil localities and insufficient exposure of the fossiliferous strata. Additionally, age estimates by mammalian evolution and correlation often have uncertainties greater than ~1–2 million years. Here we present new magnetostratigraphic results of the Baogeda Ula Fauna, which was generally assigned an early Baodean Age (Late Miocene), or equivalent to the European MN12 zone (middle Turolian). Hipparion remains and associated vertebrate fossils were excavated from the upper part of the fluvio-lacustrine Baogeda Ula Formation near Abaga Banner, central Inner Mongolia of northern China. At least two layers of basalt sheet flows can be observed on top of the Baogeda Ula Formation. Our magnetostratigraphy, aided by published biochronology data and K–Ar ages of the lower basalt layer suggests that the Baogeda Ula Fauna consisting of three fossiliferous horizons can be placed within chron C4n.1n with an age range of 7.642–7.528 Ma. Thus, the Baogeda Ula Fauna becomes the first and only Baodean assemblage that is constrained by both magnetostratigraphy and radiometric ages, offering an anchoring point for future biochronological correlations.