Sha Li

The ~ 66 Ma Cretaceous/Paleogene (K/Pg) boundary coincides with a severe mass extinction widely attributed to the Chicxulub impact and consequent abrupt climatic changes. However, it is unclear how long the subsequent climatic disruptions affected terrestrial and marine environments and what caused them. Here, we present magnesium isotope (δ²⁶Mg) and Chemical Index of Alteration data from an expanded section on Seymour Island, Antarctica, where a new cyclostratigraphic age model provides millennial-scale resolution. Pre-boundary weathering indices, including δ²⁶Mg values, record a stable, mild weathering regime. Post-boundary weathering saw a transition to a substantially variable regime with intervals of intense weathering revealed. This environmental instability persisted for at least 43.89 kyr after impact, and may reflect the climatic influence of Deccan volcanism. Thus, whilst the Chicxulub impact can be directly implicated in mass extinction, the recovery interval was substantially affected by Deccan volcanism.

The Carnian Pluvial Episode (CPE; 234–232 million years ago) is an iconic but poorly understood hyperthermal event. Here, we present an integrated high-resolution (~2–10 kyr) multi-proxy record from a Carnian lacustrine succession of the Junggar Basin of northwestern China. We find that the rapid CPE onset (~15.8 kyr) could have been the result of volcanism and subsequent surface carbon-cycle feedbacks. The CPE terrestrial carbon cycling, at a scale of ± 1‰ (δ¹³C_org), displays an in-phase relationship with the 405-kyr-long-eccentricity parameter, paralleling the warmhouse climate–carbon-cycle interactions throughout the Oligo–Miocene. The CPE hydrological cycle was typified by increased aridification in continental interiors and multiple precipitation centres at low-latitude eastern regions of Pangea and at the poles. The carbon and hydrological cycle changes of the CPE include features reminiscent of other warm events, suggesting they may share key characteristics and hold important clues to Earth system functioning.

A latest Paleocene charophyte flora collected from the South Gobi area in the Junggar Basin, western China, includes the geographically widespread taxa Peckichara torulosa var. varians (Dollfus and Fritel, 1919) Sanjuan, Vicente, and Eaton, 2020, Lychnothmanus vectensis (Groves, 1926) Soulié-Märsche, 1989, and Gyrogona lemani capitata Grambast and Grambast-Fessard, 1981. Lychnothmanus vectensis (as Lychnothmanus aff. L. vectensis) is known from the Cretaceous–Paleocene transition in eastern China and the latest Paleocene in western China, with likely additional records from the United States (Utah). The earliest European records of L. vectensis are from the late Eocene to early Oligocene in Spain, France, and England. Similarly, the oldest record of G. lemani capitata is from the latest Paleocene in the South Gobi area, with younger records from the middle Eocene of France. These latest Paleocene gyrogonite assemblages demonstrate the origin of these charophyte lineages in Asia. The dispersal of these charophytes from Asia to Europe in the middle to late Eocene appears to have occurred before the retreat of the Turgai Strait in both the Tarim area and the Siberian Basin by the end of the late Eocene and before the “Grande Coupure” in Europe and the Mongolian Remodelling in Asia during the Eocene–Oligocene transition. We hypothesize that waterbirds may have facilitated this intercontinental dispersal, and that idea is supported by the shared occurrence of avian groups in Central Asia and Europe in the middle and late Eocene.

A new aeshnoid dragonfly, Jingguaeshna taoae gen. et sp. nov., is described based on an incomplete hindwing from a new Miocene deposit in Jinggu, Yunnan Province, southwestern China. Jingguaeshna gen. nov. is most likely a member of the Telephlebiidae, sharing a number of typical characters of this family. Jingguaeshna taoae gen. et sp. nov. is the first aeshnoid dragonfly fossil found from Yunnan and probably the oldest-known telephlebiid dragonfly. This study also reveals a new entomofauna in southwestern China, contributing new information to the understanding of the Miocene ecosystems in this region.