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Jurassic Sprinters: Hot Evidence for Debate on Dino Speed

Oct 15, 2015 08:05 AM EDT
Tachiraptor admirabilis

(Photo : Maurílio Oliveira via AAAS)

It turns out that Jurassic hunters may have really been the terrifying sprinters that Hollywood has made them out to be. New research has revealed that careful body temperature regulation had many dinosaurs 'running hot,' but only on sunny days.

Paleontologists and evolutionary biologist have been in a heated debate over dinosaur speed for a very long time, with some parties arguing that most dinos were no faster than the sluggish alligators and crocodiles we see today.

That's not to say that alligators are slow. The animals are stunningly quick when snapping up unsuspecting prey. However, unlike the dinosaurs sprinting around box office hit Jurassic World,  these modern-day terrors spend most of their time conserving energy and lazing in the sun to regulate body temperature.

It would then not be unreasonable to assume that crocodiles, who have evolved much slower than birds -- dinosaurs' other modern descendants -- are then a prime example of how ancient hunters actually behaved.

Still the idea of velociraptors or the iconic Tyrannosaurus rex just lazing around all day is certainly not as fantastic an image as what has filled out childhood dreams. That's why experts recently set out to be sure, and what they've found could end the speed debate.

Led by Robert Eagle, a researcher at UCLA College, a team of scientists examined 70- and 80-million year old dinosaur eggshell fossils from Argentina and Mongolia, respectively. The chemistry of these shells allowed them to determine the temperature at which the eggshells formed.

In other words, the experts were able to learn the internal body temperature of an expecting mamma-dino. The results were published in the journal Nature Communications.

"This presents the first the direct measurements of theropod body temperatures," co-author Aradhna Tripati excitedly announced. (Scroll to read on...)

Artist's interpretation of oviraptorid theropods, small dinosaurs that were closely related to Tyrannosaurus rex and birds.
(Photo : Doyle Trankina and Gerald Grellet-Tinner / UCLA) Artist's interpretation of oviraptorid theropods, small dinosaurs that were closely related to Tyrannosaurus rex and birds.

Interestingly, the Argentine fossils, eggshells from long-necked titanosaur sauropods, hinted at significantly warmer temperatures than the Mogoli shells. Those second fossils were from the Gobi desert, and belonged to much smaller oviraptorid theropods, relatives of the T-rex.

This backs the theory that dinosaurs we neither cold-blooded nor warm blooded, but a mix between the two.

"At least some dinosaurs were not fully endotherms like modern birds," Eagle explained. "They may have been intermediate -- somewhere between modern alligators and crocodiles and modern birds."

So how does this help settle the speed debate?

"This could mean that they produced some heat internally and elevated their body temperatures above that of the environment but didn't maintain as high temperatures or as controlled temperatures as modern birds," Eagle added. "If dinosaurs were at least endothermic to a degree, they had more capacity to run around searching for food than an alligator would."

That may not necessarily mean that velociraptors would be happy to sprint alongside a very determined Chris Pratt in the middle of the night, as seen in Jurassic World. However, it does mean that there is a much better chance that it could happen -- you know... if we brought dinosaurs back to life in the 21st century. A man can dream.

For more great nature science stories and general news, please visit our sister site, Headlines and Global News (HNGN).

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