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New study may solve mystery about warm-blooded dinosaurs
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Scientists once thought of dinosaurs as sluggish, cold-blooded creatures. Then research suggested that some could control their body temperature, but when and how that shift came about remained a mystery.
Now, a new study estimates that the first warm-blooded dinosaurs may have roamed the Earth about 180 million years ago, about halfway through the creatures’ time on the planet.
Warm-blooded creatures — including birds, who are descended from dinosaurs, and humans — keep their body temperature constant whether the world around them runs cold or hot. Cold-blooded animals, including reptiles like snakes and lizards, depend on outside sources to control their temperature: For example, basking in the sun to warm up.
Knowing when dinosaurs evolved their stable internal thermometer could help scientists answer other questions about how they lived, including how active and social they were.
Davide Bonadonna/University of Vigo/University College London via AP
To estimate the origin of the first warm-blooded dinosaurs, researchers analyzed over 1,000 fossils, climate models and dinosaurs’ family trees. They found that two major groups of dinosaurs — which include Tyrannosaurus rex, velociraptors and relatives of triceratops — migrated to chillier areas during the Early Jurassic period, indicating they may have developed the ability to stay warm. A third crop of dinosaurs, which includes brontosaurs, stuck to warmer areas.
“If something is capable of living in the Arctic, or very cold regions, it must have some way of heating up,” said Alfio Allesandro Chiarenza, a study author and a postdoctoral fellow at University College London.
The research was published Wednesday in the journal Current Biology.
Jasmina Wiemann, a postdoctoral fellow at the Field Museum in Chicago, said a dinosaur’s location is not the only way to determine whether it is warm-blooded. Research by Wiemann, who was not involved with the latest study, suggests that warm-blooded dinosaurs may have evolved closer to the beginning of their time on Earth, around 250 million years ago.
She said compiling clues from multiple aspects of dinosaurs’ lives — including their body temperatures and diets — may help scientists paint a clearer picture of when they evolved to be warm-blooded.
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GOP, Democratic strategists on Biden’s next steps with calls for him to drop out growing
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U.S. troops leaving Niger bases this weekend and in August after coup, officials say
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The U.S. will remove all its forces and equipment from a small base in Niger this weekend and fewer than 500 remaining troops will leave a critical drone base in the West African country in August, ahead of a Sept. 15 deadline set in an agreement with the new ruling junta, the American commander there said Friday.
Air Force Maj. Gen. Kenneth Ekman said in an interview that a number of small teams of 10-20 U.S. troops, including special operations forces, have moved to other countries in West Africa. But the bulk of the forces will go, at least initially, to Europe.
Tech. Sgt. Christopher Dyer / AP
Niger’s ouster of American troops following a coup last year has broad ramifications for the U.S. because it is forcing troops to abandon the critical drone base that was used for counterterrorism missions in the Sahel.
Ekman and other U.S. military leaders have said other West African nations want to work with the U.S. and may be open to an expanded American presence. He did not detail the locations, but other U.S. officials have pointed to the Ivory Coast and Ghana as examples.
Ekman, who serves as the director for strategy at U.S. Africa Command, is leading the U.S. military withdrawal from the small base at the airport in Niger’s capital of Niamey and from the larger counterterrorism base in the city of Agadez. He said there will be a ceremony Sunday marking the completed pullout from the airport base, then those final 100 troops and the last C-17 transport aircraft will depart.
Speaking to reporters from The Associated Press and Reuters from the U.S. embassy in Niamey, Ekman said that while portable buildings and vehicles that are no longer useful will be left behind, a lot of larger equipment will be pulled out. For example, he said 18 4,000-pound (1,800-kilograms) generators worth more than $1 million each will be taken out of Agadez.
Unlike the withdrawal from Afghanistan, he said the U.S. is not destroying equipment or facilities as it leaves.
“Our goal in the execution is, leave things in as good a state as possible,” he said. “If we went out and left it a wreck or we went out spitefully, or if we destroyed things as we went, we’d be foreclosing options” for future security relations.
AFP via Getty
Niger’s ruling junta ordered U.S. forces out of the country in the wake of last July’s ouster of the country’s democratically elected president by mutinous soldiers. French forces had also been asked to leave as the junta turned to the Russian mercenary group Wagner for security assistance.
Washington officially designated the military takeover as a coup in October, triggering U.S. laws restricting the military support and aid.