Fossil eggshells from some of the largest dinosaurs ever discovered have been unearthed in a surprisingly cooler climate distant from the equator. Despite the immense size of titanosaurs, they could not rely on brooding to keep their volleyball-sized eggs warm, as they were too large, as explained by University of Calgary paleontologist Darla Zelenitsky.
A recent study, led by University of Tsukuba paleontologist Kohei Tanaka and co-authors from Japan and Argentina, examined microscopic pores on the eggshells to uncover the incubation technique used by titanosaurs. The researchers suggest that titanosaurs likely buried their eggs in warm mounds of decaying vegetation, similar to the method employed by modern crocodiles.
Titanosaurs were colossal herbivorous dinosaurs characterized by their long necks and tails, weighing up to 75 tonnes, comparable to half the size of a blue whale. Fossilized volleyball-sized eggs known as Fusioolithus have been associated with titanosaurs and were previously discovered in warmer regions. However, fragments of Fusioolithus eggshells were found in the Chorrillo Formation in southern Argentina, dating back to the Late Cretaceous period.
The Chorrillo Formation, once located at a latitude equivalent to Red Deer, Alta., boasted a climate akin to present-day New York City. The region showcased a diverse ecosystem where titanosaurs like Nullotitan glaciaris and other dinosaurs coexisted with various fauna including crocodiles, snakes, turtles, and mammals.
To ensure the successful development and hatching of their embryos, dinosaurs needed to maintain optimal egg temperatures for extended periods. While smaller dinosaurs likely brooded their eggs, titanosaurs resorted to burying them in warm environments. The study’s findings on the porosity of titanosaur eggshells from the Chorrillo Formation supported the theory that these eggs were buried for incubation.
The research underscores the adaptability of dinosaurs, showcasing their ability to thrive and reproduce in varied environments. Tsu-Ruei Yang, an expert in vertebrate paleontology, expressed interest in further exploring the nesting strategies of titanosaurs to unravel their evolutionary success and global dispersion during the Late Cretaceous era.