Abstract The Junggar Basin, NW China, hosts continuous and well-exposed Late Triassic and Jurassic continental strata. Extensive coal, oil and gas deposits occur within the basin and, together with the high-palaeolatitude locality and continental records of several Mesozoic geological events, make the sedimentary successions globally important. This special publication focuses on these successions, presenting recent advances in palaeontology, geology and palaeoenvironments. The contents span various topics, including studies of fauna, flora, stratigraphy, geochemistry, palaeogeography, palaeoclimate, petroleum reservoir quality, the end-Triassic mass extinction, the Toarcian Oceanic Anoxic Event, Triassic–Jurassic seasonal freezing and true polar wander. To provide continuity throughout the various papers, where possible, bed numbers for all stratigraphic units are provided, enabling findings to be compared among studies and tested in the future. This special publication highlights that the sediments of the Junggar Basin provide important long-term records of continental life and environmental changes through the Triassic and Jurassic.

Abstract In the Junggar Basin, northwestern China, the biostratigraphy and vegetation patterns of the Middle–Late Triassic sediments are comparatively poorly resolved. Here we investigate Middle–Late Triassic successions of the Dalongkou Section in the southern Junggar Basin for palynostratigraphy and vegetation patterns. Three palynological abundance zones are proposed here: the Aratrisporites Abundance Zone (Middle Triassic), the Dictyophyllidites – Aratrisporites Abundance Zone (latest Middle to early Late Triassic) and the Lycopodiacidites – Stereisporites informal abundance zone (Late Triassic). A review of previous records of the Fukangichthys Fauna indicates that this vertebrate fossil assemblage is stratigraphically located within the uppermost part of the Karamay Formation and is Middle Triassic in age. The revised dating of this and other faunas are further used to constrain the palynological zones in the Junggar Basin. Although the palynoflora is consistently dominated by non-striate bisaccate pollen (produced by seed ferns and/or conifers) in the studied section, spores record a distinctive abundance increase during the late Middle Triassic. Spore taxon abundance changes indicate a vegetational shift from a Middle Triassic–early Late Triassic community characterized by abundant lycophytes (likely Annalepis and Pleuromeia) to a Late Triassic ecosystem with abundant dipteridaceous ferns (e.g. Dictyophyllum) in the Junggar Basin and across North China. This study updates the Triassic biostratigraphy in the Junggar Basin, and sheds light on temporal floral changes in this basin and elsewhere in North China during the Middle to Late Triassic.