Dinosaurs Took A Middle Road Between Warm- And Cold-Blooded b4in.org/b4Lo There has been a long-standing debate over dinosaurs: were they cold-blooded like modern day reptiles or warm-blooded like mammals? In the early days of science, and in Hollywood, these prehistoric beasts were depicted as slow, lumbering giants as they were believed to be cold-blooded. But over the past few decades, these animals have been portrayed as swift-moving lizards, more reminiscent of warm-blooded behaviors. New research, led by John Grady, a graduate student at the University of New Mexico, has possibly solved the mystery of dinosaur metabolism, stating dinosaurs were neither cold-blooded (ectothermic) nor warm-blooded (endothermic). Instead, he and his team paint a picture of something more in between. “Most dinosaurs were probably mesothermic,” said Grady in a statement. “A thermally intermediate strategy that only a few species – such as egg laying echidnas or great white sharks – use today.” METABOLIC EVIDENCE Publishing a paper in the journal Science, the team demonstrate the first evidence to quantitatively explore the relationship between growth rate and metabolic rates in animals and extend that to those which have been long extinct – namely the dinosaurs. Grady and his colleagues, which included fellow graduate students Eva Dettweiler-Robinson and Natalie Wright, along with supervision from Prof Felisa Smith of UNM and Prof Brian Enquist of the University of Arizona, used an extensive database of animal growth and energy use that was developed by Grady himself to demonstrate that animals which grow fast not only require more energy, but also have higher body temperatures. Using growth estimates of extinct dinosaurs, the team then calculated dinosaur metabolic rates, unexpectedly finding that dinosaurs followed a more intermediate road between mammals and reptiles. “I think we were all surprised by this,” Smith said. “The idea certainly took some getting used to. But, the patterns were so robust.” “Our results showed that dinosaurs had growth and metabolic rates that were actually not characteristic of warm-blooded or even cold-blooded organisms. They did not act like mammals or birds nor did they act like reptiles or fish,” Enquist told Reuters’ Will Dunham. “Instead, they had growth rates and metabolisms intermediate to warm-blooded and cold-blooded organisms of today. In short, they had physiologies that are not common in today’s world.” More b4in.org/b4Lo
Posted on: Fri, 13 Jun 2014 23:00:11 +0000
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