Written by Steve McAnon, CNN

Global warming may have made some dinosaurs extinct, but scientists now know a lot more about what it does for the dinosaurs that lived and died long before modern humans took to the Earth.

Hardened eggshells unearthed in the Sundarban Hills of Nepal reveal the chemical composition of dinosaur eggs -- showing that they were once warmer than they are today, but also a little colder.

Researchers believe that fossilized dinosaurs made out like bandits, cooling their eggs down with a combination of fire and rain, and leaving their hatchlings hot and thirsty.

Their big heads can cope with the constant heat from rapid, massive body growth, but the thickness of the eggs, the size of the interior water-filled cavity and the efficiency of the cooling process suggest the dinosaurs were adding water and ice to the solution before it dried up.

"The warm dinosaur eggs are worth their weight in gold to paleontologists, because in many ways they offer an insight into the living conditions of the dinosaurs during the age of the dinosaurs -- a time when the world was experiencing major shifts in temperature," said Timing in the Archaeological and Paleontological Sciences group at London's Natural History Museum, which discovered the examples.

"Lack of nutrients would have taken its toll on hatchlings whose diets would have consisted mainly of palm fronds to compensate for lack of food.

"Some scientists believe that the humid conditions may have been ideal for the survival of animals in temperate regions," they added.

The team discovered evidence of large pools of evaporated or dissolved water, indicating that the cold blood flowing through the dinosaur embryos was already well below freezing before it reached the cells.

Dinosaur eggs were effectively art, researchers claim

"As far as we know, heat from burning charcoal and rainwater are the only ways that fuel could help to slow the disappearance of these dinosaurs," lead researcher Frank Hanssens, an archaeologist at the University of Bonn in Germany, told CNN.

"On the other hand, there's no way of knowing how the incubation conditions affected dinosaurs' ability to feed their young well," he said.

In a previous study of Neanderthal pollen, scientists found evidence of elephant dung in early human burials. Having a couple of dinosaurs of a similar size to the human ancestors is particularly interesting, suggesting they may have interbred in this period of history.

These large creatures were far from the only ones to give birth at temperatures as high as 145 degrees Fahrenheit (68 degrees Celsius). A record of about 1,300 dinosaur eggs was found in the Hadrosauric sandstone in the Soviet Republic of Kazakhstan.

The findings will be presented at a conference in Ohio later this month.

"So much is known about today's dinosaurs and their environment, but little of this scientific material covers the dinosaurs before, during, and after the age of the dinosaurs," said Hanssens.