Isotopic hallmark of mid-palaeolatitude titanosaurian eggs

LEA LEUZINGER; STEFANO BERNASCONI; MARTÍN HECHENLEITNER; LUCAS FIORELLI; PABLO ALASINO

Mendoza

Jornada; 34º Jornadas Argentinas de Paleontología de Vertebrados; 2021

Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales

suited for palaeoecological reconstructions based on oxygen and carbon stable isotope analyses. Their resistance to dia-genesis makes them valuable substitutes of bioapatite remains when highly mineralized skeletal remains such as teeth arescarce or absent. We present a new set of conventional (δ18O and δ13C) and clumped (Δ47) stable isotope compositions oftitanosaurian eggshells from the recently discovered Late Cretaceous nesting site of Quebrada de Santo Domingo, La RiojaProvince, northwestern Argentina. Comparisons with isotopic data from other titanosaurian nesting sites worldwide revealclear clusters, one of which is interpreted as the isotopic hallmark for well-preserved, mid-palaeolatitude titanosaurianeggs (δ13CVPDB= -15 to -11‰; δ18OVSMOW= 27 to 33‰). This implies that the physiological processes linked to egg formationacross Titanosauria were comparable, and that representatives of that clade needed similar environmental conditions fornesting, independently of their geographical location. The definition of an isotopic range for well-preserved titanosaurianeggshells shall help to recognize close-to-pristine material, especially when the alteration is cryptic and did not affect themicrostructure of the oological remains. Additionally, we offer new data on the body temperature of titanosaurians sug-gesting that it may have been higher than previously published. Finally, we show that Riojan titanosaurians needed condi-tions more arid than the long-term average for nesting, further supporting the hypothesis that these dinosaurs were breeding migrants.