Some dinosaurs used heat of the sunlight or microbial decay to warm their eggs, while others brooded, a study by a team including a researcher from Nagoya University suggests.
The study by the team including Japanese researcher Kohei Tanaka was published online in the British journal Scientific Reports. While the fossils of dinosaur eggs and nests have been discovered across the globe, it was not clear how dinosaurs warmed their eggs.
To understand nesting habits, the team researched species including alligators and birds which take advantage of surrounding heat to warm their eggs, as they are similar to dinosaurs. They found that the nesters mainly used microbial decay to warm their eggs when the nesting material consisted of dirt or plants, and sunlight in sandy nesting locations. The researchers used this knowledge to analyze 192 fossilized dinosaur nests.
The nests of some sauropods -- giant herbivorous dinosaurs having a small head and a long neck -- were found in coarse-grained sediment such as sandstone. This led researchers to presume that these dinosaurs used solar radiation or geothermal heat to incubate their eggs.
For the hadrosaurus, a herbivorous dinosaur whose face is like the platypus, researchers concluded it was possible microbial decay was used for incubation because hadrosaurus nests were mainly discovered in fine-grained deposits such as mudstone.
The scientists also analyzed nests of troodontids, small carnivorous dinosaurs similar to birds, including eggs. The fossils were discovered in both fine-grained and coarse-grained deposits, indicating that the eggs were hatched in any type of environment. This supported the theory that these dinosaurs brooded.
Tanaka, who works as a special researcher at Nagoya University Museum, commented, "I want to utilize differences in the ways of warming eggs to shed light on the habitats of dinosaurs."