The storied Northwest Passage was one of those things that Europeans believed in a lot longer than they should have. Many lives were lost trying to find the way from the North Atlantic to the North Pacific and back again, quite literally through what is now Canada. No such thing as it turned out. Also, as it turns out, our ancestors were several thousand years too late. Once upon a time there was a kind of waterway through North America which is now called the Western Interior Seaway. And that thing up there, which is now called a xiphactinus, lived in it.
This article from Canadian Broadcasting Co. online gives you the rundown on a fossil xiphactinus found in what was once the Western Interior Seaway. The skeletal remains were found in 2009 - not surprisingly, the jaw was located first - but it wasn't until recently that Canadian scientists wanted to announce with certainty what they had found. The most interesting thing to me, besides the ancient seaway itself, is the fact that the xiphactinus was found with the fossilized remains of a monasaur flipper in those jaws.
According to Canadian Fossil Discovery Centre curator Anita Janzic, the find is pretty unusual at best. She says in the article:
It's quite remarkable to have the opportunity to find one fossil, and absolutely incredible when that one fossil leads to the discovery of an ancient sea monster skeleton.
The article is very short on information about xiphactinus. Disappointingly so, in fact. It chooses to drift off into stumping for the CFDC and it's need for funds for a new building in the last five paragraphs rather than sticking to the alleged topic. From what I could find out, the monsters were large; probably comparable to some modern sharks. They had bones and a spine and the jaw was not only wide but - again like a shark - could be opened to accommodate the equally large prey they would find in the seaway during the Cretaceous period.
It's a tantalizing look at a time when fish like big X up there dominated the seaways the way the Royal Navy would by the 18th century of our modern era. And just another reason to be thankful you didn't live in the fish-eat-mammal, hard scrabble Cretaceous.