Cretaceous Formation refers to a time period of 65 to 140 million years ago. This is a long time period where Dinosaurs- Ruled and evolved. T-Rex lived for 15 million years, between 80 and 65 million years ago. Extinction of the Dinosaurs and the end of the Cretaceous Period is due to a large asteroid that hit in the Yucatan- Gulf of Mexico region... Cretaceous Dig Digging fossil cones from the top of a layer of coal. Wide open spaces in South Dakota. Charlie preparing to hunt dinosaur bones. A great view entering Bad Lands of Hell Creek Formation (65-140 million years old). A view of cliffs in the Bad Lands possibly holding secrets of Dinosaur fossils. What was the top of an exposed bone reveals a well preserved rib. Beginning to dig past what was exposed on surface and the first vertebrae reveals another large vertebrae. Much more of the puzzle coming to light. This piece was quite a job to save, and to anexperienced observer to be the head gear that went back on a specides of Triceratops Dinosaur. So this confirmed that I was digging on a Triceratops site. Another one of the mystery bones one might find until more is carefully exposed and glued to hold its shape frozen in time. This mystery bone looks to be part of the pelvis with a rib bone almost beneath it. With bones eroding out of the hard muddened bank, one digs further hoping to find more skeletal remains as revealed. Beginning to dig in the bank reveals a vertebrae on the outer area and another vertebrae and a couple of ribs. Hours of careful digging reveals several bones to a triceratops; four vertebraes and two ribs are visable. One has to carefully dig around all bones and glue any loose pieces of bone to its proper place.