Zircon geochronology of the new dinosaur fauna in the Middle Jurassic lower Shaximiao Formation in Chongqing, SW China

New macronarian from the Middle Jurassic of Chongqing, China: phylogenetic and biogeographic implications for neosauropod dinosaur evolution

“…[15–18]). Recently, a new zircon U-Pb age from Yunyang geochronology yielded a maximum depositional age of 166.0 ± 1.5 Ma (late Middle Jurassic) below the bone-bearing horizon of the Lower Shaximiao Formation [19]. In general, we suggest the bone-bearing horizon may belong to the Bathonian.…”

“…Although a series of detrital zircon U-Pb geochronology for this formation in the Sichuan Basin was carried on, the accurate age for this formation is still controversial (e.g. [15][16][17][18] Jurassic) below the bone-bearing horizon of the Lower Shaximiao Formation [19]. In general, we suggest the bone-bearing horizon may belong to the Bathonian.…”

“…The age for this formation is still controversial, traditionally it has been suggested to be Middle Jurassic, based on regional stratigraphic correlations and sedimentology [4][5][6] and specifically, potentially Bajocian to Bathonian based on some invertebrate remains [7][8][9][10][11][12], but Bathonian-Callovian-Oxfordian based on recent detrital zircon geochronological age (e.g. [13][14][15][16][17][18][19]). The Lower Shaximiao Formation has yielded the remains of several diverse faunas of terrestrial vertebrates [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38], including seven sauropod genera (Shunosaurus, Protognathus, Omeisaurus, Abrosaurus, Dashanpusaurus, Datousaurus, Bashunosaurus).…”

Limited flexural control of fold-thrust belts on the Jurassic Sichuan Basin, South China

“…These two sections were correlated using regional makers, such as maximum flooding surfaces, regional black shale beds or mudstone, and limestone tops. Stratigraphic ages were constrained and assigned based on published isotopic ages (Xu et al, 2017;Xu et al, 2021;Zhou et al, 2022) and biostratigraphic studies (Wang et al, 2018;Huang, 2019), using the timescale by Gradstein and Ogg, (2020). Although these ages are with uncertainties, they will not significantly influence the results and conclusions.…”

A sauropod from the Lower Jurassic La Quinta Formation (Dept. Cesar, Colombia) and the initial diversification of eusauropods at low latitudes

“…The comparisons below are restricted to vertebrae from the anterior-to-middle part of the dorsal series. For this reason, we exclude from comparisons several pre-Late Jurassic sauropods for which there are no dorsal vertebrae or for which no information is available, such as Vulcanodon (Africa) or Nebulasaurus , Chinshakiangosaurus , and Anhuilong (Asia), as well as sauropods whose age assignments have been moved forward into the Late Jurassic, such as Shunosaurus (Oxfordian; Wang et al, 2018; but see Zhou et al, 2022) and Rhoetosaurus (early Oxfordian or younger; Todd et al, 2019).…”