CONICET | Buscador de Institutos y Recursos Humanos

Titanosauria is a clade of huge herbivorous dinosaurs whose representatives are known on all the continents, including Antarctica. Evidence currently suggests that this diverse group of sauropods used a variety of nesting sites worldwide. The rarity and nature of these nesting sites, combined with their abundance of egg clutches and eggs, indicate that sauropod dinosaurs were potentially colonial nesters and migrated to the same locations ('nesting-site fidelity') to lay their eggs. Historically, studies on nesting sites have focused on egg systematics, including diagnosis of eggs and eggshells fragments, which has resulted in a parataxonomic classification scheme. This trace fossil parataxonomy creates serious problems for understanding the paleobiological aspects of reproduction, as this classification scheme does not meet biological and evolutionary criteria. To date, no investigation has focused on the ecological and geological basis for the selection of titanosaur nesting sites that are distributed worldwide. Observations were performed on a series of well-known Cretaceous nesting sites in Argentina, South Korea, Romania, India, France and Spain. Preliminary observations strongly suggest that titanosaurs did not use the classic ?sit-on-eggs? incubation strategy typical of most modern dinosaurs, and instead must have relied on external environmental heat for incubating their egg clutches. Taking into account clutch composition and geometry, the nature of the sediments and their properties, and eggshell structures and conductance, it appears that titanosaurs adopted nesting behaviors comparable to those displayed by modern megapodes. This family of birds displays wide and specific nesting strategies, such as burrow-nesting in diverse media and mound building, which could explain the lack of true nesting traces, despite the overwhelming abundance of egg clutches in these nesting sites.

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