【ゆっくり解説】1億2500万年前、恐竜は水中へ進出した――古代の水域を支配した「水中恐竜」たちの正体

125 million years ago, some dinosaurs had already moved beyond terrestrial habitation and ventured into aquatic environments such as rivers, lakes, and wetlands. This video focuses on Spinosaurus and provides a detailed explanation of the body structure, ecology, hunting methods, and ongoing scientific debate surrounding ancient aquatic dinosaurs. Ichthyosaurs, mosasaurs, plesiosaurs, and marine crocodiloids that swam in the seas of the Mesozoic era are not dinosaurs. However, studies of fossils, trace fossils, tail structure, bone density, snout, teeth, and hind limbs have revealed the possibility that some dinosaurs not only lived near water but also evolved to hunt prey in the water. [Image caption: Swimming traces of a large theropod discovered in Spain.] [Image caption: Spinosaurus with conical teeth that made it difficult for fish to escape.] [Image caption: A massive tail that pushes water, and dense bones that may have reduced buoyancy.] Furthermore, we'll introduce dinosaurs whose relationship with aquatic environments is being debated, including Baryonyx, Suchomimus, Halsukaraptor, Natvenator, Austroraptor, Buitreraptor, and Liaoningosaurus. Did Spinosaurus really track fish in the water? Were Halsukaraptor and Natvenator swimming dromaeosaurids? And how far did dinosaurs actually venture into aquatic environments? With each new fossil discovered, the boundary between dinosaurs and water is being rewritten little by little. We'll explore, with the latest research, how dinosaurs, once thought to be land-only rulers, lived in ancient aquatic environments. If you're interested in ancient creatures, dinosaurs, evolution, extinction, and paleontology, please subscribe to our channel.