My first, entirely understandable response was "Hey, there's no such thing as aquatic dinosaurs! Silly!" Then I clicked the link and read the article. It's about the discovery that placoderms, which were prehistoric armored fishes, gave birth to live young. We've found a placoderm mother in the process of giving birth, with umbilical cord still attached (more here). Which is a really, really cool discovery!
But the title of the piece is, once again, Dating Habits of Aquatic Dinosaurs Revealed. Not placoderms. I can only guess that whoever dreamed up the headline was using the term "dinosaur" the way we might refer to an old car as a "dinosaur."
Only, it's really, grossly, stupidly irresponsible to use the word in this way to describe another prehistoric creature. Not only that, the article described the fish as the "Incisoscutum species of Placoderms." Weird capitalization aside, the placoderm is actually called Incisoscutum ritchei. That makes "incisoscutum" the name of the genus.
Seriously dude, you're a science writer. For a science website. For crying out loud!