Fragments of 255 fossilized titanosaur eggshells from Argentina’s Chorrillo Formation show the giant sauropods reproduced in cold high-latitude regions about 68 million years ago.
The find undercuts the long-held view that titanosaurs nested only in warm near-equatorial zones, even though their bones had been found from Antarctica to Texas and Mongolia.
Researchers say the dinosaurs likely buried eggs in mound nests of soil, sand and vegetation, where heat from decay could incubate them without adults sitting on the clutch.
Very porous eggshells also suggest the eggs had to be covered to retain moisture, supporting the idea that titanosaurs left the nest after laying rather than providing direct parental care.
The study broadens evidence of how some of Earth’s largest dinosaurs adapted breeding strategies to harsh southern climates.