That's huge! Imagine what it woud be like having one of these monsters living today!
But how on earth was a 150 feet 100 tonnes terrestrial creature able to succesfully roam this planet for 18.7 million years? Could it not only have been gignatic, but also fairly fast and agile? How on earth was it even able to support it's own weight without collapsing? The vast majority of enormous animals live in the ocean, why? Because it doesn't take nearly as much strength to support your own weight when you are in water. When whales are washed up on the shore, they don't die because of lack of oxygen, they die because they are crushed under their own weight. Gravity must've functioned different millions of years ago.