Wikipedia:Main Page history/2020 December 19
From today's featured articleAchelousaurus was a ceratopsid dinosaur that lived about 74.2 million years ago, during the Late Cretaceous. The first fossils of the genus were collected from the Two Medicine Formation in the U.S. state of Montana in 1987. Mainly known from skull material, Achelousaurus was about 6 m (20 ft) long, with a weight of about 3 tonnes (3.3 short tons). It had a large head with a hooked beak, and a bony neck-frill with a pair of long, curved spikes. In the places where other centrosaurines often had horns, Achelousaurus had bosses (roundish protuberances) above the eyes and on the snout that may have been used in fights and for display. It has been suggested that Achelousaurus was a transitional form between Einiosaurus (which had spikes but no bosses) and Pachyrhinosaurus (which had larger bosses), though this is debated. As a ceratopsian, Achelousaurus would have been a herbivore. It appears to have had a high metabolic rate, though lower than that of modern mammals and birds. (Full article...)
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NGC 6357 is a diffuse nebula in the constellation Scorpius. This composite image of the nebula contains X-ray data from the Chandra X-ray Observatory and the ROSAT telescope (purple), infrared data from the Spitzer Space Telescope (orange), and optical data from the SuperCosmos Sky Survey (blue). Radiation from hot, young stars is energizing the cooler gas in the clouds that surround them. Often known as the Lobster Nebula, the astronomical object has also been termed the Madokami Nebula by fans of the anime Madoka Magica due to its supposed resemblance to the main character. Scientists at the Midcourse Space Experiment prefer the name War and Peace Nebula, because the bright, western part resembles a dove, while the eastern part looks like a skull in infrared images. Photograph credit: NASA
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