Dinosaur species laid eggs like reptiles, brooded like birds, new study finds

The birds we see immediately are the predecessor of a dinosaur that realized to fly and survived a mass extinction 66 million years in the past, however little is thought about their transition.

Though they have been the one species to outlive the Cretaceous interval, not a lot was identified about how comparable the dinosaurs and modern-day birds may be.

A small piece of a dinosaur eggshell, concerning the measurement of a fingernail, was central to a global examine printed within the journal Proceedings of the Nationwide Academy of Sciences on Monday, serving to to unravel the prehistoric creature’s reproductive system. reconstruct and decide its physiology, metabolism and physique temperature. .

The Troodon, believed to be a meter-long carnivorous dinosaur, is assumed to have given rise to birds, mentioned Francois Therrien, a paleontologist on the Royal Tyrrell Museum in Drumheller, Alta., who is among the authors of the examine.

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The examine, he mentioned, “may give us plenty of details about what occurred throughout that transformation from a typical carnivorous dinosaur to a fowl, (reminiscent of) answering questions on whether or not the birds truly inherit a lot of the traits of carnivory. dinosaurs.”

Therrien added that the transition was a gradual one, one thing researchers discovered by similarities the dinosaur had with modern-day reptiles and birds.

The examine discovered that Troodons have been warm-blooded animals with a reproductive system much like immediately’s reptiles, however in addition they had the power to reasonable their physique temperature much like birds.

Whereas Troodon eggs resembled a fowl’s egg in form and floor, the feminine dinosaur had two ovaries and will lay two eggs at a time, like these of reptiles.

It additionally means a feminine Troodon might lay 4 to 6 eggs per clutch, mentioned Darla Zelenitsky, a dinosaur paleobiology professor on the College of Calgary.

“We might see that the dinosaur produced its eggs very slowly, which is typical of contemporary reptiles,” says Zelenitsky, who can be one of many authors of the examine.

Feminine birds have one ovary and may lay an egg each one or two days. Researchers are usually not clear whether or not the evolutionary lack of an ovary occurred amongst non-avian dinosaurs or after the transition to birds.

The examine used a way referred to as double-lump isotope thermometry to measure the heavier styles of oxygen and carbon within the eggshell fossils to find out the physique temperatures of Troodons and to higher perceive the dinosaur’s reproductive system.

The findings have been then matched with eggshells from modern-day reptiles, reminiscent of crocodiles, alligators and sure species of turtle, in addition to birds reminiscent of chickens, sparrows, wrens and ostriches.

The dinosaur nestlings, some discovered at two websites in southern Alberta, contained as much as 24 eggs, suggesting that feminine Troodons laid eggs in communal nests, that are seen amongst birds, together with ostriches.

“It’s attainable that some (Troodon) moms got here collectively to construct communal nests and lay all their eggs, then share the duties of guarding and incubating all of the eggs in flip,” Therrien mentioned.

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The nests additionally mirrored intelligence among the many Troodons, Therrien and Zelenitsky mentioned. The dinosaurs buried the eggs vertically within the nest with the pointed facet down and the blunt facet up, which might have improved incubation.

The eggshell fossils, saved on the Royal Tyrrell Museum, have helped scientists reconstruct the Earth’s floor temperature to higher perceive the physique temperature of the dinosaur and the mineralization processes of the fossils.

Oxygen isotope clustering and carbon crystallization, which depend upon temperature, additionally revealed the physique temperature of the species.

Troodon dinosaurs are believed to have laid eggs at between 30 C and 42 C. The species had a resting physique temperature of 42 C, which may very well be lowered to 30 C relying on their atmosphere, much like birds.

Scientists are actually whether or not Troodons might have survived in humid areas in numerous elements of the world, versus the semi-arid areas the place the eggs have been first found.

“Most individuals suppose that it’s a must to discover full dinosaur skeletons to have the ability to say one thing about its biology and the animals after they lived,” Therrien mentioned.

“With the examine, we are able to actually get into how an animal functioned by finding out the isotopic composition of the eggshell you could’t get from finding out bones alone.”

Researchers are actually Troodon eggs from completely different websites and from time intervals to see if the patterns discovered on this examine are nonetheless in line with different eggs.

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