While most, if not all, dinosaurs were able to doggy-paddle for brief periods of time, some must have been more accomplished swimmers than others. For example, it would only make sense if fish-eating theropods like Suchomimus and Spinosaurus were able to swim, since falling into the water ...
In fact, there is hard evidence for one unusual way in which dinosaurs communicated. Manyhadrosaurs, or duck-billed dinosaurs, were equipped with elaborate head crests. The function of these crests may have been exclusively visual in some species (say, recognizing a fellow herd member from afar...