He and his colleagues analyzed the chemical makeup of ancient eggshells, using a technique previously perfected on teeth to estimate the temperature of the body they formed in.
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They found that body temperature of dinosaur differed widely.
Were dinosaurs warm or cold blooded? With a mass spectrometer, researchers could measure these isotopic bonds in fossilized eggs. Mineral forming inside colder bodies has more clustering of isotopes.
“So the abundance of these bonds reflects the body temperature of the female when the eggshell forms”, Eagle explains. That enabled them to estimate that the environmental temperature in Mongolia shortly before the dinosaurs went extinct was approximately 79 degrees Fahrenheit. Like modern mammals and birds, they would have generated body heat internally. “Comparing the outcomes to trendy game birds takes off daylight on the development with this trait”. “They were kind of part way to evolving endothermy”.
“There are two possible explanations”, Eagle says.
So did a few dinosaurs have bird-like metabolisms, and the hot blood to match? So oviraptorids were still able to elevate their body temperature above their surroundings. Warm-blooded animals, also known as endotherms, are capable of internal body regulation.
D’Emic thinks we shouldn’t expect to be able to infer a “typical” dinosaur physiology from any one species. “There is a huge array of questions that can be asked”.
A great debate amongst paleontologists for over a century has revolved around whether dinosaurs were warm blooded endotherms like mammals, or cold-blooded ectotherms like modern reptilia.
The basic findings line up with what most recent research in the area has concluded: Dinosaur metabolisms were all over the place.
The research is published today in the journal Nature Communications.
Eggshells are made from calcium carbonate, a hard brittle substance that comes in subtly different variations. They determined whether the fossilized eggshells maintain their original chemistry or were altered over tens of millions of years. The isotopes – carbon-13 and oxygen-18 – tend to cluster together more closely at colder temperatures. The researchers used a similar method a few years ago to estimate dinosaur temperature using teeth.
This new technique, which the researchers first tried out and verified on 13 bird species and nine reptiles, allows them to determine the body temperature of the dinosaur that laid the eggs. Smaller, two-legged omnivorous oviraptors were estimated to have had a body temperature of 89.4 degrees Fahrenheit. The smaller dinosaurs had substantially lower temperatures, probably below 90 degrees. The dinosaurs were warmer than that, but only just.
Warm blooded animals need to eat a lot to stay warm, necessitating hunts or eating plants. “If dinosaurs were endothermic to a degree, they had more capacity to run around searching for food than alligators would”.
The answers offered new insights into dinosaurs’ body temperatures-and a long-standing debate.
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Depending on the temperature at which they formed, those materials contain different proportions of isotopes-atoms of the same chemical element that vary slightly in mass. But the technique works only if the material being analyzed is well-preserved, says Robert Eagle, an evolutionary biologist at the University of California, Los Angeles. “They may have been intermediate-somewhere between modern alligators and crocodiles and modern birds; certainly that’s the implication for the oviraptorid theropods”. “This presents the first direct measurements of theropod body temperatures”.
