Quetzalcoatlus, genus made up of two species of giant pterosaurs classified in the family Azhdarchidae, which contains some of the largest known flying animals. Both species lived during the Maastrichtian Age (72.1 million to 66 million years ago) of the Cretaceous Period. One of them, Quetzalcoatlus northropi, is widely believed to have been the largest flying creature that ever lived....

　　Burmese python, (Python bivittatus), species of constrictor snake that is native to various environments in southern and Southeast Asia, including several islands in Indonesia, and is known for its exceptional size and its environmental adaptability. Burmese pythons inhabit mangrove forests, rainforests, swamps, grasslands, rivers, and rocky areas, in a range extending from Nepal, Bangladesh, northeastern India, and Myanmar (Burma) eastward...

　　 　　reticulated python (Malayopython reticulatus)Reticulated python (Malayopython reticulatus) coiling around a branch. One individual of this species of Asian python attained a length of 10 meters (32.8 feet).(more)reticulated python, (Malayopython reticulatus), species of giant constricting snake belonging to the python family, Pythonidae, and known for being the longest living snake in the world, with the largest recorded individual measuring 10...

　　American alligator, (Alligator mississippiensis), species of alligator inhabiting freshwater rivers, lakes, and swamps and brackish waters in the Southern U.S. and northeastern Mexico. The alligator’s geographic range extends from the Mexican states of Coahuila, Nuevo León, and Tamaulipas northeastward to Oklahoma and Arkansas and eastward through the Gulf Coast to North Carolina, South Carolina, Georgia, and Florida. The species is...

　　 　　American crocodile (Crocodylus acutus)American crocodiles (Crocodylus acutus) basking in the sun in Costa Rica. Usually solitary, the reptiles bask for most of the day and then enter the water during the evening to hunt.(more)American crocodile, (Crocodylus acutus), moderately large species of crocodile inhabiting forests and freshwater environments, as well as brackish and marine intertidal environments, in Florida, Central America,...

　　spectacled caiman, (Caiman crocodilus), species of alligator-like reptiles common to swamps, other wetlands, and waterways in Central America and northern South America. The spectacled caiman takes its name from its most prominent distinguishing feature, a bony ridge between the eyes that resembles the nosepiece of a pair of eyeglasses. The species has adapted to a wide variety of habitats, and...

　　 　　 Sweden’s history as a sovereign state stretches back a thousand years, though its boundaries were often changing until the early 19th century. These 14 buildings provide useful snapshots of how the country’s distant past has influenced its more recent history. 　　Earlier versions of the descriptions of these buildings first appeared in 1001 Buildings You Must See...

　　 　　 Norway, by some estimates, is two-thirds mountainous, and about half of its population lives in the south of the country, where its capital, Oslo, is located. These eight contemporary buildings will give you another lens through which to see this Scandinavian country. 　　Earlier versions of the descriptions of these buildings first appeared in 1001 Buildings You Must...

　　 　　Sure, you’ve seen Meet Me in St. Louis and might even know all about Chuck Berry, Cardinals baseball, and St. Louis blues music. But the Gateway to the West is known for much more than that—much more, even, than we can cover in a short list. We can try, though! Here, in no particular order, are...

　　 　　megamouth shark (Megachasma pelagios)Schoolchildren looking into the tooth-lined mouth of a 4.2-meter- (13.8-foot-) long preserved megamouth shark (Megachasma pelagios) specimen at Tokai University Marine Science Museum in Shizuoka, Japan.(more)megamouth shark, (Megachasma pelagios), species of large filter-feeding sharks inhabiting the continental shelf and open-ocean regions of tropical and temperate oceans worldwide. The species is found between latitudes 40° N and...

　　 　　 Quite a few islands around the world are very large, and many of them are countries. Australia is technically an island because it is unconnected to any other body of land, but it is more commonly considered a continental landmass. Of the seven continents, Australia is the smallest, at 2,969,976 square miles, or 7,692,202 square kilometers. However,...

　　Arthropleura, genus of exceptionally large extinct millipede-like arthropods that thrived from the Viséan Age of the Carboniferous Period to the Asselian Age of the Permian Period (346.7 million to 293.52 million years ago) and are known from their fossilized exoskeletons. Members of Arthropleura are the largest known arthropods in Earth’s history, with an estimated length exceeding 2.6 meters (8.5 feet)—roughly...