アメリカ自然史博物館さんのインスタグラム写真 - (アメリカ自然史博物館Instagram)「Nyctosaurus lived about 85 million years ago, during the Late Cretaceous. With a wingspan of 6 to 10 feet (1.8 to 3.0 meters), this pterosaur also had two long, thin bones sticking out of its head, probably connected by soft tissue, forming a large crest. Scientists have many theories about why pterosaur crests evolved, which include recognizing one's own species, cooling, or even steering through the air. But without living descendants for comparison, and because pterosaur fossils are so rare, it's impossible to say for sure. Another leading theory for why pterosaurs evolved crests is sexual selection—perhaps, as with peacocks’ tails, the larger the crest, the more likely a pterosaur was to attract a mate. Photo: C. Chesek/©AMNH」8月22日 13時10分