Geochemical characteristics of newly discovered Elongatoolithidae eggs from the Upper Cretaceous of Jiangxi Province, southern China: Palaeoenvironmental and palaeoclimatic inferences. (July 2019) - He, Qing
Abstract: We analyzed identified oospecies and associated geochemical characteristics of newly discovered dinosaur eggs from the Cretaceous Hekou Formation in Yudu District, Jiangxi Province, China. Results reveal that the Yudu eggs can be identified as representatives of the known oospecies Macroolithus rugustus within Elongatoolithidae based on external shape, size, ornamentation, and internal microstructure between the columnar and cone layers. The major element found in Macroolithus rugustus shells is Ca, while trace elements mainly include Sr, Ba, As, Cr, Mn, Pb, Cd, La, and Ir, characterised by Ir and Sr abnormalities, as well as the toxic elements As and Pb. Enrichment of trace elements in shells might be due to the diet of dinosaurs and subsequent deposition in eggs, consistent with global Ir anomalies and the regional enrichment of trace elements. δ 13 C values for Macroolithus rugustus ranging between −8.81‰ and −7.65‰ are indicative of C3 plants with relatively high CO2 concentration and low mean annual precipitation (MAP), while δ 18 O values ranging between −8.51‰ and 3.14‰ indicate relatively low humidity and the alteration of water sources of female dinosaur. The Sr and Ca contents as well as δ 18 O values of eggshells could be associated with the drinking water and food materials together with dissolved bone apatite. In light of the red-brown colour of surrounding rocks, high Fe composition revealed by macroelement analysis, and the presence of a C3 vegetation with low MAP, the palaeoenvironment of Yudu dinosaur nesting area was most likely to be fluvial and the palaeoclimate was semi-arid to arid, which is conducive to the preservation of eggs. Graphical abstract: Image 1 Highlights: The newly discovered dinosaur eggs from Yudu area, Jiangxi Province can be referred to Macroolithus rugustus . Four trace elements (Sr, Ir, As and Pb) of dinosaur eggshells are abnormal in the study area near the K/Pg boundary. The δ 13 C and δ 18 O values of dinosaur eggshells show the C3 plants with relatively high CO2 content, low MAP and humidity. The higher elemental and isotopic values of dinosaur eggs in the Yudu area show a drier climate in the Late Cretaceous.