Laying under stressful conditions: temporal occurrence of pathologic sauropod eggshells in the Late Cretaceous of northeastern Iberian Peninsula

摘要: In living archosaurs (crocodiles and birds), pathologic eggs and eggshells appear as a consequence of disturbance in biological and/or environmental conditions. Because eggshell is a physiologically controlled biomineralized tissue, a prolonged retention of the egg within the oviduct may produce several irregularities in the eggshell structure (Hirsch, 2001). Dinosaur oological record provides several examples of pathological eggshells, having been recognized in ornithopod, sauropod and non-avian theropod eggs (Zelenitsky & Hills, 1997; Zhao et al., 2001; Bravo et al., 2005; Jackson & Schmitt, 2008). Among all pathologic oological types, the most common and well known phenomenon is the multilayered eggshell, but other types of abnormalities have also been recognized (Jackson & Schmitt, 2008). An accurate evaluation of the purported pathologic remains is essential for avoiding misinterpretation (Hirsch, 2001; Grellet-Tinner et al., 2010).The presence of pathologic dinosaur oological remains in Europe has been associated to climatic changes (Dughi & Sirugue, 1958, 1976; Erben, 1970, Thaler, 1965), or even to dinosaur demise (Erben et al., 1979). Nevertheless, the former interpretation has never been explored in detail, and the latter one has been widely rejected (Kerourio, 1981; Penner, 1985; Vianey-Liaud et al., 1994; Jackson & Schmitt, 2008). After sampling more than 70 stratigraphic levels of 35 different eggshell-sites in the Tremp Formation of South-Central Pyrenees (Catalonia), we recovered several multilayered, abnormal ornamented and extra spherulitic pathologic eggshells, mainly affecting Megaloolithus siruguei …