NSF: Research sheds new light on 150-year-old dinosaur temperature debate.- La investigación arroja nueva luz sobre el debate de temperatura de los dinosaurios de hace 150 años de edad,

Hola amigos: A VUELO DE UN QUINDE EL BLOG., La evidencia muestra algunos dinosaurios elevan su temperatura corporal utilizando fuentes de calor como el sol: ¿Eran los dinosaurios rápidos, cazadores agresivos como los de la película "Jurassic World"? ¿O es que tienen tasas metabólicas más bajas que las hicieron más como caimanes y cocodrilos de la actualidad?
Durante 150 años, los científicos han debatido sobre la naturaleza de la temperatura corporal de los dinosaurios y cómo influyó niveles de actividad.

More infomation.....

http://www.nsf.gov/news/news_summ.jsp?cntn_id=136426&WT.mc_id=USNSF_51&WT.mc_ev=click

Evidence shows some dinosaurs elevated their body temperatures using heat sources such as the sun

Scientists used a new technique to find out dinosaurs' body temperatures based on their eggshells. Credit and Larger Version

October 13, 2015

Were dinosaurs fast, aggressive hunters like those in the movie "Jurassic World"? Or did they have lower metabolic rates that made them more like today's alligators and crocodiles?

For 150 years, scientists have debated the nature of dinosaurs' body temperatures and how they influenced activity levels.

Research by National Science Foundation (NSF)-funded scientists, including John Eiler of the California Institute of Technology, indicates that some dinosaurs had the capacity to elevate their body temperatures using heat sources in the environment, such as the sun.

The researchers also believe the animals were probably more active than modern-day alligators and crocodiles, which can be energetic, but only for brief spurts.

The evidence shows that some dinosaurs had lower body temperatures than modern birds, their only living relatives, and were probably less active.

The research results are published today in the journal Nature Communications.

"These scientists used a relatively new isotope analysis technique on fossil eggshells to investigate thermal regulation in non-avian dinosaurs," says Rich Lane, program director in NSF's Division of Earth Sciences, which funded the research. "Comparing the results to modern birds sheds light on the evolution of this trait."

Led by Robert Eagle, a researcher at UCLA, the scientists examined fossilized dinosaur eggshells from Argentina and Mongolia. Analyzing the shells' chemistry allowed them to determine the temperatures at which the eggshells formed.

"This technique tells you about the internal body temperature of the female dinosaur when she was ovulating," says Aradhna Tripati, a co-author of the study and a UCLA geologist. "This presents the first direct measurements of theropod body temperatures."

The Argentine eggshells, which are approximately 80 million years old, are from large, long-necked titanosaur sauropods, members of a family that includes the largest animals to roam the Earth--relatives of Brontosaurus and Diplodocus.

The shells from Mongolia's Gobi desert, 71 million to 75 million years old, are from oviraptorid theropods, much smaller dinosaurs that were related to Tyrannosaurus rex and birds.

Sauropods' body temperatures were warm--approximately 100 degrees Fahrenheit. The smaller dinosaurs had substantially lower temperatures, probably below 90 degrees.

Warm-blooded animals, or endotherms, produce heat internally and maintain their body temperatures, regardless of the temperature of their environment; they do so mainly through metabolism. Humans and other mammals fall into this category.

Cold-blooded animals, or ectotherms, including alligators, crocodiles and lizards, rely on external environmental heat sources to regulate their body temperatures. Lizards, for example, often sit on rocks in the sun to absorb heat, which allows them to be active.

Scientists have long debated whether dinosaurs were endotherms or ectotherms. The research indicates that the answer could lie somewhere in between.

"The temperatures we measured suggest that some dinosaurs were not fully endotherms like modern birds," Eagle says. "They may have been intermediate--somewhere between modern alligators and crocodiles, and modern birds. That's the implication for the oviraptorid theropods.

"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. If dinosaurs were endothermic to a degree, they had more capacity to run around searching for food than alligators would."

The researchers also analyzed fossil soils, including minerals that formed in the upper layers of soils on which the oviraptorid theropod nests were built. That enabled them to estimate that the environmental temperature in Mongolia shortly before the dinosaurs went extinct was approximately 79 degrees Fahrenheit.

"The oviraptorid dinosaur body temperatures were higher than the environmental temperatures--suggesting they were not truly cold-blooded, but intermediate," Tripati says.

Eagle, Tripati and their colleagues initially looked at modern eggshells from 13 bird species and nine reptiles to establish their ability to determine body temperatures from the chemistry of eggshells.

The researchers measured, in calcium carbonate minerals, the subtle differences in the abundance of chemical bonding between two rare, heavy isotopes: carbon-13 and oxygen-18.

They studied the extent to which these heavy isotopes clustered together using a mass spectrometer--a technique that enabled them to determine mineral formation temperatures. Minerals forming inside colder bodies have more clustering of isotopes.

The scientists analyzed six fossilized eggshells from Argentina, three of which were well-preserved, and 13 eggshells from Mongolia's Gobi Desert, again selecting three that are well-preserved.

The answers offered new insights into dinosaurs' body temperatures--and a long-standing debate.

Co-authors of the journal paper are also with the University of Alabama, Tuscaloosa; Germany's University of Mainz; Columbia University; California State University, Fullerton; California State University, Los Angeles; Orcas Island Historical Museum; CONICET, Argentina; Boise State University; University of Utah; and the Natural History Museum of Los Angeles County.

-NSF-

Media Contacts Cheryl Dybas, NSF, (703) 292-7734, cdybas@nsf.gov
Stuart Wolpert, UCLA, (310) 206-0511, swolpert@support.ucla.edu

Related WebsitesNSF Grant: Insights into Dinosaur Body Temperatures, Physiology, and Environments from Clumped Isotope Thermometry:
 http://www.nsf.gov/awardsearch/showAward?AWD_ID=1024929&HistoricalAwards=false

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2015, its budget is $7.3 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives about 48,000 competitive proposals for funding, and makes about 11,000 new funding awards. NSF also awards about $626 million in professional and service contracts yearly.

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Oviraptor fossils that were part of the study were found in the Gobi Desert's Flaming Cliffs.
Credit and Larger Version

Titanosaur eggshell fossils from Argentina sites held new clues in dinosaur temperature questions.
Credit and Larger Version

A large clutch of titanosaur eggs has been cleaned for research.
Credit and Larger Version

A titanosaur egg, a remnant of ancient history, is viewed by researchers today.
Credit and Larger Version

The key to new discoveries lies in this titanosaur egg, a remnant of the long-ago past.
Credit and Larger Versión
The National Science Foundation (NSF)
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