A new way to tell whether dinosaurs were hot or cold-blooded has been found.
This question has been a topic of heated debates among paleontologists, who accused each other of acting more like politicians than scientists.
The dinosaurs were thought to be slow, lumbering, and cold-blooded like the modern reptiles they are today being crocodilians.
There have been hints that this isn't the case.
There are growing signs that dinosaurs may have been warm-blooded.
Some of them are descendants of the hot- running birds that have the highest metabolism.
Some argued that dinosaurs might not have been endotherms or cold-blooded, and that there could be a third option. Today's turtles burn internal energy to regulate their body temperature, but not as much as mammals and birds do.
A new method developed by a Yale University paleologist allows researchers to calculate the metabolism of dinosaurs using their fossils.
Metabolicism is how we convert oxygen into chemical energy that fuels our body. Side products that interact with our bodies are converted into waste. Warm-blooded animals need a higher metabolism to fuel themselves.
We don't know how the fossilization process alters minerals in the bones, so it's hard to rely on previous attempts to get metabolic indicators. The breathing waste product is stable.
We have developed a new proxy that targets the by-products of molecular aerobic respiration. Aerobic respiration involves converting oxygen into chemical energy, a cascade of processes that release heat which eventually determines an animal's ability to actively thermoregulate... pic.twitter.com/njnIQY2iyU
— Dr. Jasmina Wiemann (@jasmina_wiemann) May 25, 2022
The researchers hunted for signs of this telltale waste using the bones of 55 different animals.
The amount of breathing waste found in the bones of different species was compared to calculate a scale of waste to metabolism. They used this to calculate the metabolism of extinct animals.
The question of whether dinosaurs were warm-blooded or cold-blooded is one of the oldest questions in paleontology, and now we think we have a consensus that most dinosaurs were warm-blooded.
The lizard-hipped saurischians had similar metabolisms to the cold-blooded reptiles we know today. Many of the other groups ran fast.
Some ornithischians, including Stegosaurus, Triceratops, and a hadrosaur secondarily reduced their metabolic rates to those found in modern ectotherms (i.e., lizards), suggesting thermoregulatory behaviors such as seasonal migration, sun basking, or preferences for warm climates. pic.twitter.com/go7HaIYe9V
— Dr. Jasmina Wiemann (@jasmina_wiemann) May 25, 2022
It was suggested that endothermy was present in the ornithodiran ancestors of pterosaurs before they split from their dinosaur relatives. Birds have a very ancient trait called high endothermy.
The results rule out the hypothesis that birds and mammals may have survived the mass extinction event due to their warm-blooded nature. Many dinosaurs who were wiped out shared this trait.
One of the key advantages when it comes to surviving mass extinctions is having a high metabolism.
We are living in the sixth mass extinction, so it is important for us to understand how modern and extinct animals responded to previous climate change and environmental changes, so that the past can inform our future actions.
Nature published their research.
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