Fossilised dinosaur eggshells helped scientists estimate the internal body temperatures of two kinds of dinosaurs: sauropods and oviraptors.
Researchers used chemical analysis on dinosaur eggs from the Gobi desert in Mongolia and from Argentina, to figure out the body temperature of oviraptors and of titanosaurs (long-necked herbivorous sauropod dinosaurs).
Robert Eagle, a researcher in the Department of Earth and Space Sciences at University of California, Los Angeles, believes that knowing whether the dinosaurs were cold blooded or warm blooded could shed more light on their psychology and behavioural patterns (for instance hunting methods).
Some palaeontologists suggested that dinosaurs were cold blooded creatures much like lizards; other disagreed and said that they had a metabolic rate similar to mammals and birds, and were thus warm blooded.
To provide more scientifically accurate results, Dr. Eagle decided to base his analysis on chemistry.
Calcium carbonate – compound of oxygen, calcium, and carbon – is a mineral that makes up the hard eggshell exterior. When calcium carbonate is formed, oxygen-18 and carbon-13 (rare chemical isotopes) bind together.
Oxygen-18 and carbon-13 tend to bind more when the temperatures are lower, and less at higher temperatures. Using a mass spectrometer, the researchers calculated the levels of isotopic bonds in the dinosaur eggshells.
“The abundance of these bonds reflects the body temperature of the female when the eggshell forms,” Dr. Eagle said.
It is possible that sauropods generated their heat internally, much like modern-day mammals and birds, which means that they were warm blooded. On the other side of the spectrum, the oviraptors turned out to be partly cold blooded (intermediate ectotherms), having slower metabolic rates than modern birds.
According to Dr. Eagle there may be two possible explanations as to why this difference occurred: either the dinosaurs (sauropods and oviraptors) really had different metabolic rates, or the larger dinosaurs (sauropods) retained a lot more heat from the environment given their enormous size.
The difference between warm blooded (endotherms) animals and cold blooded (ectotherms) animals is that the ones that are warm blooded have the ability to regulate their internal body heat, while the cold blooded creatures rely on their environment for heat.
Image Source: nationalgeographic