Fossil eggshells believed to belong to some of the largest dinosaurs ever discovered have been located in a surprisingly cool region far from the equator. The gigantic titanosaurs couldn’t warm their volleyball-sized eggs by sitting on them due to their massive size, as pointed out by University of Calgary paleontologist Darla Zelenitsky. A recent study published by Zelenitsky and researchers from Japan and Argentina has uncovered that titanosaurs likely utilized a unique incubation method to maintain the necessary warmth for hatching without direct nesting.
Analyzing the microscopic features of the eggshells, the researchers propose that titanosaurs employed a similar incubation approach seen in modern crocodiles by burying their eggs in warm piles of decomposing vegetation. Titanosaurs were colossal, long-necked, herbivorous dinosaurs weighing up to 75 tonnes, comparable to half the mass of a blue whale. Fossilized volleyball-sized eggs associated with titanosaurs, known as Fusioolithus, have been previously discovered in warmer climates. However, in recent years, fragments of Fusioolithus eggshells were found in the Chorrillo Formation at the southern tip of Argentina, dating back to the Late Cretaceous period.
The Chorrillo Formation, once positioned at a latitude equivalent to Red Deer, Alta., boasted a climate resembling that of present-day New York City. The diverse ecosystem within the formation included the titanosaur Nullotitan glaciaris, measuring up to 25 meters in length, along with smaller herbivores and carnivorous dinosaurs. The discovery of titanosaurs’ eggs in such a cool environment surprised Zelenitsky, highlighting the challenges faced by larger animals in terms of survival and reproduction.
Dinosaurs needed to maintain warmth for their eggs to develop and hatch, requiring incubation for extended periods. While smaller dinosaurs could brood their eggs for warmth, titanosaurs could not due to their immense size relative to the eggs. Alternative incubation methods observed in modern species like sea turtles and crocodiles involve burying eggs in warm environments. The researchers found evidence of buried titanosaurs’ eggs by measuring the porosity of the eggshells, indicating adaptation to different environmental conditions.
The study showcases the remarkable adaptability of dinosaurs, emphasizing how even the largest of them found ways to thrive in diverse habitats. Tsu-Ruei Yang, an expert in vertebrate paleontology, suggested that the success and global spread of titanosaurs may be linked to their varied nesting strategies. He pointed out the importance of further research to fully understand the nesting behaviors of titanosaurs throughout different time periods.