Hi, I'm Barb Graves, interpretive park ranger at Zion National Park. On behalf of the park staff, I'd like to welcome you to Zion and its majestic sedimentary rocks. The rocks of Zion represent a smorgasbord of paleo environments, including shallow marine, coastal, desert sand dunes, rivers, and lakes. Zion's fossil plants, animals, and tracks provide a window to past life beginning more than 245 million years ago. Imagine a scene here from one of those earliest times. Salty, shallow water lightly laps the shoreline where brachiopods and gastropods and crinoids fan out on the silty bottom. If we come forward millions of years from then, large reptiles lounge and forage in the afternoon sun along drainages. Forests of large conifers cover the inland areas. That was the scene right here 220 million years ago during the Chinle formation’s paleo environment, where today Zion’s petrified wood records that conifer forest evidence. Other Chinle fossils include bone fragments, fish and reptile teeth, plant material, and invertebrate burrows. Chinle's terrestrial vertebrate body fossils include phytosaur and crocodile-like reptile remains. Perhaps the most impressive fossil evidence is dinosaur imprints and casts that were found in the formations behind me, deposited after the Chinle formation. Dozens of Meonave and Kayenta formation tracks are preserved in place, including eubrontes and grallator tracks from therapod or three-toed dinosaurs. Paleontologists give different names to these tracks than to the dinosaurs who created them, because it's very difficult to link the two. The most probable dinosaur for the creation of this grallator later track is Megapnosaurus, a lizard-like, 70 pound meat eater about ten feet long from the tip of the tail to the nose. The eubronte's track maker was likely a Dilophosaurus-like dinosaur that may have been 20 feet long and weighed up to 1,500 pounds. Some fossil skeletons found elsewhere indicate that these dinosaurs hunted in packs, running up to 30 miles per hour. If evolution had taken another path, we might be walking along the Pa’rus trail today with a herd of dinosaurs thundering toward us. We hope that you'll join us soon at Zion to experience its unique geologic stories and stone.