Dinosaurs were likely warm-blooded, says a new study

A new study shows that dinosaurs were likely warm-blooded.

Researchers at the University of Barcelona made the finding after analyzing the growth lines, also called "LAGs," around dinosaur bones, which had until now been assumed to be caused by the creatures' internal heat, rather than warm blood.

Yet, the scientists have shown that all mammals have growth lines, like tree rings – a phenomenon caused by changing seasonal conditions that can inhibit the growth of cold-blooded animals, said TG Daily.

While cold-blooded animals grow in fits and starts, it is believed that mammals grow continuously.

According to Live Science, the study looked at the bones of 100 mammals, including gazelles, sheep and cows.

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They found that they also had growth lines, which changed due to seasonal conditions, and that those lines were similar to those found on dinosaur fossils.

The presence of those lines in dinosaur fossils had, until now, been the clearest indicator that dinosaurs were cold-blooded.

"It may seem surprising that until now there has not been a similar systematic study to prove or disprove whether it is only ectotherms that leave these marks in their bones during growth," said study author, Meike Köhler of the Catalan Institute of Palaeontology in Barcelona, in a press release.

Experts say that the study does not definitively show that dinosaurs were indeed warm-blooded.

"It’s probably not going to close the debate whether dinosaurs were warm-blooded or not,” said paleontologist Martin Sander of the University of Bonn in Germany, according to Science News, “but the argument that [rest lines] mean cold-blooded is certainly not valid any longer.”

The study was published in the journal Nature.