The Limited Times

Now you can see non-English news...

New study aims to seal dispute over whether dinosaurs were hot or cold blooded

2022-05-25T19:29:42.532Z


The question of whether the blood that flowed through dinosaurs was hot or cold has long preoccupied paleontologists, until now.


Great Argentine discovery: dinosaur eggs discovered 0:54

(CNN) --

Fearsome predators like T. rex and towering, long-necked dinosaurs like Brachiosaurus were warm-blooded creatures just like birds and mammals, according to a groundbreaking new study.


The question of whether the blood that ran through the gigantic structures of the dinosaurs was hot or cold, like that of reptiles, is one that has long preoccupied paleontologists.

Knowing this fundamental fact could shed light on the life of these prehistoric creatures in a significant way.

Warm-blooded animals have a high metabolic rate: they take in a lot of oxygen and need a lot of calories to maintain their body temperature, while cold-blooded animals breathe and eat less.

"The question of whether dinosaurs were warm-blooded or cold-blooded is one of the oldest in paleontology, and we now think we have a consensus that most dinosaurs were warm-blooded," said study lead author Jasmina Wiemann, a postdoctoral researcher at the California Institute of Technology, in a press release.

Recent attempts to answer this question have suggested that dinosaurs were warm-blooded, but those results, which involved analysis of growth rings or chemical isotope signals in bones, were ambiguous because fossilization can change these markers. .

Furthermore, those analysis techniques damage the fossils, making it difficult to create a large data set.

However, Wiemann and his colleagues devised a new and, in their view, more definitive method for assessing a dinosaur's metabolism.

advertising

Is it the definitive answer?

The researchers looked at the waste that forms when oxygen is inhaled into the body and reacts with proteins, sugars and lipids.

The abundance of these waste molecules, which appear as dark-colored spots on fossils, scales with the amount of oxygen ingested and is an indicator of whether an animal is warm-blooded or cold-blooded.

A microscopic view of soft tissue removed from an Allosaurus bone is shown.

The molecules are also extremely stable and do not dissolve in water, meaning they are preserved during the fossilization process.

Wiemann and his team analyzed the femur (thigh bone) of 55 different creatures, including 30 extinct and 25 modern animals.

Among the samples were bones from dinosaurs, giant flying reptiles called pterosaurs, marine reptiles such as plesiosaurs, and modern birds, mammals, and lizards.

The scientists used a method called infrared spectroscopy, which focuses on the interactions between molecules and light.

This technique allowed them to quantify the number of residue molecules in the fossils.

The team then compared those results to known metabolic rates of modern animals and used that data to infer metabolic rates of extinct creatures.

(Left to right) This illustration shows Plesiosaurus, Stegosaurus, Diplodocus, Allosaurus, and Calypte (modern hummingbird), with shades of red indicating warm-blooded and blue for cold-blooded.

the findings

Early generations of paleontologists had grouped dinosaurs with reptiles, suggesting that they had a reptilian appearance and lifestyle.

Today, most paleontologists agree that dinosaurs were much more bird-like after the discovery of feathered fossils in the 1990s, which led to the understanding that modern birds are directly descended from dinosaurs.

The study, published Wednesday in the academic journal Nature, found that dinosaur metabolic rates were typically high and in many cases higher than those of modern mammals, which typically have body temperatures of around 37C. , and more similar to those of birds, which have an average body temperature of around 42 °C.

"With our new evidence for avian-level ancestral metabolism in all dinosaurs and pterosaurs, all warm-blooded dinosaurs probably had high body temperatures, comparable to those of modern birds," Wiemann said by email.

However, there were notable exceptions.

Dinosaurs classified as ornithischians, an order characterized by lizard-like hips and including instantly recognizable creatures like Triceratops and Stegosaurus, evolved to have low metabolic rates comparable to those of modern cold-blooded animals.

  • 'Extremely rare' fossil of giant flying reptile discovered on Scottish island

"Lizards and tortoises sit in the sun and bask, and we may have to consider similar 'behavioral' thermoregulation in ornithischians with exceptionally low metabolic rates. Cold-blooded dinosaurs might also have had to migrate to warmer climates. warm during the cold season, and climate could have been a selective factor for where some of these dinosaurs could live," Wieman said.

It has been proposed that having a high metabolic rate is one of the reasons birds survived the mass extinction that wiped out the dinosaurs 66 million years ago.

However, Wiemann said this study indicated that this was not true: Many dinosaurs with exceptional bird-like metabolic abilities went extinct.

The research will "dramatically change" how we interpret the biology and behavior of many extinct animals, said Jingmai O'Connor, associate curator of fossil reptiles at the Field Museum in Chicago, who was not involved in the study.

"I consider these results pretty definitive. Wiemann's methods are painstaking and thoroughly tested," he said.

"Some dinosaurs were warm-blooded, this was the ancestral state, but others secondarily evolved to be ectothermic (cold-blooded). The next question is why and what this means about their behavior, ecology and evolution."

dinosaurs

Source: cnnespanol

All news articles on 2022-05-25

You may like

Trends 24h

Latest

© Communities 2019 - Privacy

The information on this site is from external sources that are not under our control.
The inclusion of any links does not necessarily imply a recommendation or endorse the views expressed within them.