05/26/2024 – 17:27
Intense volcanic activity changed the Earth’s climate, causing dinosaurs to adapt, shows a study carried out in Spain. Two large groups became warm-blooded and were able to migrate from one habitat to another. Dinosaurs had to face major climate changes between 250 and 65 million years ago, caused by high levels of volcanic activity. Now, a new study led by scientists in Vigo, Spain, has investigated how certain species have adapted to this: by developing warm blood.
For a long time, paleontologists assumed that dinosaurs were ectothermic, that is, cold-blooded, animals. This means they didn’t need much food and stimulated their metabolism through sun and heat.
However, cold-blooded animals are very dependent on the weather. Today’s reptiles, fish and insects, for example, are in this group and need exposure to the sun to regulate their temperature.
It has been known for some time that two of the three large groups of dinosaurs were warm-blooded, that is, they were endothermic – just like us humans and all other mammals and birds today.
Warm-blooded dinosaurs needed more food but had a higher metabolism, which made them less dependent on weather factors. Because they were endotherms, they depended more on a regular supply of food.
The two groups of warm-blooded dinosaurs are called theropods (like velociraptor and tyrannosaurus) – from which our modern birds are descended – and ornithischians (like triceratops and stegosaurus). The third group, called sauropodomorphs (like Brachiosaurus), was made up of very large dinosaurs with long necks – these were cold-blooded.
Extreme climate change forced dinosaurs to adapt
Researchers at the University of Vigo wondered when and why groups of theropods and ornithischians evolved into warm-blooded animals. Through a large-scale analysis of dinosaur bones and their location, they discovered that at that time, 200 million years ago, climate change played a decisive role.
“We are not talking about climate change as we know it today, this change occurred over many thousands of years”, explains Rainer Schoch, paleontologist at the Natural History Museum in Stuttgart and specialist in amphibian and terrestrial reptile fossils.
The causes of strong climate fluctuations were the same as today: excessive CO2 pollution in the atmosphere. At that time, however, the reason was volcanoes, which were more active, releasing huge amounts of greenhouse gases into the atmosphere. This made the weather unstable. First, it cooled markedly for many thousands of years, then it became much hotter.
Many species of cold-blooded dinosaurs died out during this period because they could not cope with the fluctuations, explains Rainer Schoch.
Warm blood enabled new habitats
The exact extent of temperature fluctuations at that time cannot be reliably reconstructed, according to Schoch. However, it can be assumed that the cold phases were relatively warm compared to today. And the hot phases were much hotter by today’s standards.
During this period, two of the three major groups of dinosaurs evolved to be warm-blooded – an adaptation mechanism to climate fluctuations. “Warm-blooded animals were then able to open new habitats towards the poles and find new niches”, explains Schoch.
Without this development in the blood, today’s birds would not be able to fly. “The way birds fly requires a very high metabolism. Warm blood is an important prerequisite for this”, highlights Schoch.
Despite being cold-blooded, some species from the sauropodomorph group also survived. Due to their gigantic size and mass, they had a decisive advantage: gigantothermy, a phenomenon in which bulky ectothermic animals find it easier to maintain a constant and relatively high body temperature than smaller animals.
“The effects of climate on wildlife are the most important thing we can take away from this. We still don’t understand everything, but we will understand better if we look at the past”, emphasizes Schoch.
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