And it was as these seas rolled back that layers of sediment built up, eventually forming the mass of rock that we can see today. The fossils found there, moreover, suggest that the area was once teeming with life. Yes, the remains of plants, fish, invertebrates and even sharks have been unearthed here over the years.
But there’s one type of creature that lived here millions of years ago that keeps scientists coming back to the Hell Creek Formation: dinosaurs. Indeed, it’s famous for being the place where the most complete skeleton of a Hadrosaurid ever to be unearthed was found.
These “duck-billed” dinosaurs were placid herbivores and lived in herds. However, there was another, much more fearsome dinosaur that stalked these parts when the land was covered with woods, rivers and valleys.