A new paper:
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The main mineral of dinosaur eggshells in the Xixia Basin is calcite and minor quartz.
Two trace elements (Sr and Ir) of dinosaur eggshells in the Xixia Basin are abnormal in the early Late Cretaceous.
Î13C and Î18O values of dinosaur eggshells exhibit the C3 plants with low MAP and high mean annual temperature.
The geochemistry of dinosaur eggs and surrounding rocks in the Xixia Basin show extremely arid climate in the Late Cretaceous.
Abstract
The trace elements and isotopic compositions of macroelongatoolithid eggshells provide insights into the palaeoenvironment of these huge eggs preservation. We analysed the geochemical characteristics of newly discovered macroelongatoolithid eggs from the early Cretaceous Zhaoying Formation in the Xixia Basin, Henan Province, China. X-ray diffraction results reveal that the minerals of these eggs are predominately composed of calcite. The major elements in eggshells are Ca, Mg, K, Na, Al, Fe and Ti, and trace elements mainly include Sr, Ba, Mn, La, As, Sc, V, Cr, Co, Ni, Cu, Pb, Zn, Cd, U, and Ir. The high Sr and Ir concentrations could be caused by food materials and drinking water of dinosaurs. Î13C values of eggshells varying between -7.19â and -5.08â (average -5.69 â) indicate the C3 plants for dinosaurs with relatively high atmospheric CO2 concentration and low mean annual precipitation (MAP); further researches show that the carbon isotopic composition of atmospheric CO2 was around -4.11â to -2.19â, and the MAP was lower than 10 mm/yr. Î18O values varying between -5.72â and -3.28â (average -4.53â) show the temperature of nesting area were about 23ÂC and the drinking water was dominated by leaf water with few meteoric water. The palaeoenvironment in which these huge eggs were preserved could be interpreted as continental deposit with extremely arid climate in the early Late Cretaceous Xixia Basin based on the high Fe contents of eggshells, the low palaeoclimate index of surrounding rocks, and the extremely low MAP shown by oxygen isotope.