The dinosaurs’ adapting capacity

In Alaska and in South Australia (which at the time was joined with Antarctica) fossils of Cretaceous dinosaurs that lived in territories situated beyond the Antarctic Circle were found. At the time, the climate was not as severe as it is at present, but due to the long Polar nights, the temperatures must have been quite low in the season of low insolation, probably only a few degrees. Some researchers, when faced with these exceptional findings of animals that were traditionally believed to be cold blooded in an environment with low temperatures, hypothesized that they ventured in long migrations during the colder periods, or that they went into lethargy, somewhat like tortoises and amphibians in our times. However, a careful morphological study showed that the dinosaurs in Alaska, plumed predators (but unable to fly) which were 2-3 m long, called Troodons, and the dinosaurs in Antarctica, hypsilophodontid dinosaurs of the Leaellynasaura genus, had unusually large eyes. A particularly well preserved specimen of Leaellynasaura in which a natural cast of the brain is visible, shows that the eye lobes were also very developed. This could seem to be an adaptation to the long months of semi-darkness in the regions beyond the polar circles, which would therefore exclude the hypothesis of migration.
The capacity of nocturnal sight and the consequent possibility of hunting in the darkness too, lead to the belief that these animals were active also during the months in which there was a poor amount of light, which would therefore exclude even the hypothesis of lethargy. However, activity during the colder months necessarily implies another characteristic : homoiothermy, i.e. the capacity to regulate body temperature; in other words, dinosaurs, or at least some of them, must have been warm blooded organisms. This had already been hypothesized in order to explain the ability to move and the possibility of dispersing heat in animals with a gigantic mass, however these discoveries are probably the final proof. It is also curious, that at the opposite poles of the Earth animals evolved with physical characteristics that were so similar, a sign of the adaptation to the environment they lived in. Curiously, it seems that in the apparently more hostile environment, dinosaurs survived longer after the extinction at the end of the Cretaceous Period – perhaps because they had a better capacity to adapt, as they were used to living in a severe and difficult environment.

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