In fact, some previous studies had already questioned this hypothesis and among the international scientific community there has been increasing consensus about the idea that LAGs were not necessarily indicators of ectothermy. Similarly, examples of mammals that seemed to have LAGs in their bones had emerged. This study conclusively closes the debate.
The ICP researchers Xavier Jordana, lecturer of postgraduate studies at the Universitat Autnoma de Barcelona and Nekane Marn, PhD student at the same university, have also participated in this study.
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Discussion of the physiology of dinosaurs
The idea that dinosaurs may have been warm-blooded reptiles is not a new one. In fact for more than 40 years it has been the subject of discussion among researchers. On the one hand, the fact that they achieved sizes of dozens of metres and enormous weights in such a short time led scientists to think of an endothermic physiology, since such huge growth is only known among animals with high metabolisms. Endothermic animals, which are able to generate internal heat, can grow continuously and maintain a highly active metabolism from birth up to maturity.
Until a few years ago, however, the existence of clearly marked LAGs in the bones of vertebrates has been thought of as an indicator of ectothermic physiology or cold bloodedness. It was thought that the growth lines appeared periodically coinciding with the cold season when the animals' metabolism slowed down and growth was basically arrested.
This study shows that ruminants, which are large mammals with species capable of living in hot and cold ecosystems as well as humid and dry environments, also have LAGs whether they are living at the North Pole or in the tropics. It has therefore been demonstrated that the only indicator of the fact that dinosaurs could have been ectotherms, does not denote their thermophysiology.
|Contact: Maria Jesus Delgado|
Universitat Autonoma de Barcelona