Dinosaurs Are Not Cold-Blooded Reptiles


Dinosaurs roamed the earth for millions of years before going extinct. Yet they have gone through quite a transformation in the hundred plus years since being discovered in the early years of the 1800s. A British paleontologist coined the term Dinosauria to refer to the specific species that he had found in Great Britain. The origin of the word is Greek, roughly translating to “terribly great reptile.” Somehow the word stuck, but changed to be a more general term referring to the whole group of prehistoric animals. However, the term is not very accurate, as dinosaurs are more closely related to birds, as opposed to common cold-blooded reptiles.

Being cold-blooded is not exactly what it sounds like. Cold-blooded species do best in hotter environments. They typically move slowly, if at all in colder temperatures, because they are trying to conserve the little energy they have left from the last period of warm weather. So people pictured these scaly-skinned giants lumbering about like reptilian elephants. However, dinosaurs are being proven less like reptiles everyday, and they are now, without question not cold-blooded.

Cold-blooded beings are ectothermic. They work like solar panels, in that they rely on the outside sunlight to provide most of their energy, then they conserve in colder sunless situations, until they can get another dose of energy. Warm-blooded endothermic beings have a very fixed internal temperature, which is regulated by their metabolism generating a lion’s share of their energy. Homeothermic beings are similar to endothermic beings, except they are more reliant on their size, because larger beings lose heat faster. These animals work more like batteries. For example, large crocodiles bask on river banks for long periods to accumulate energy, they then go about their crocodile business until they need another charge on a river bank.

Dinosaurs do not fall under any of these categories. They appear to fall in the category between endothermic and ectothermic: mesothermic. Modern day examples of mesothermic animals are Great White Sharks, Tuna, Leatherback turtles and echidnae. Dinosaurs, seem to regulate their temperature with a combination of techniques. They are primarily cold-blooded, but their metabolism increases their body temperature, no doubt outside temperature helps, while their hardworking muscles finish the job and their large size keeps the temperature relatively regulated. So the dinosaurs would not have lumbered about as previously pictured, they were actually quite quick and maneuverable.

This new revelation has come from New Mexico University. Professor John Grady figured that if dinosaur bones are like tree trunks in that each ring represents a year of growth (which has already been proven), then you can quantify not only the growth rate with that information, but also the metabolic rate. So he gathered 381 different species, both living and extinct, then compared the rates of growth, mass and known metabolic rates to create new mathematical scale of representation for endothermic and exothermic species. The results showed that dinosaurs were not on the cold-blooded side of the scale, nor were on the endothermic side, but in between, in the mesothermic part of the spectrum.

However, critics have pointed out that all the mesothermic animals mentioned before regulate their temperature in different ways. They adapted to their surroundings in different ways. Therefore, there is much variation to their methods, and it is probable that the same is the case for the many species of dinosaurs. Thus there is still much more to be learned about how earth’s prehistoric giants regulated their temperatures, and soon many more revelations will be flooding in, but one thing is now certain, dinosaurs are not as simple as people once assumed, they are not cold-blooded.

By Eddie Mejia

National Geographic
LA Times

One Response to "Dinosaurs Are Not Cold-Blooded Reptiles"

  1. Lino   July 15, 2014 at 2:41 am

    Dinos are not extinct, birds are dinos!


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