On Monday, President Trump will travel to Utah to announce significant cuts to two of the state’s most remarkable national monuments, Grand Staircase–Escalante and Bears Ears. It will be the largest rollback of protections to public lands in history and could open what one paleontologist called the “last great, largely unexplored dinosaur boneyard in the lower 48 states” to coal mining and other energy development.

Today, Grand Staircase–Escalante National Monument is 1.9 million acres of spectacular desert landscapes, winding slot canyons and high plateaus, natural bridges and trickling ephemeral streams. It was the last place in the continental U.S. to be mapped and remains an unspoiled natural frontier drawing outdoor enthusiasts and scientific experts in search of adventure and exploration from across the country. The monument forms the economic backbone of local communities in southern Utah, attracting new businesses and visitors to this rural stretch of the Southwest.

But 76 million years ago, this corner of southwestern Utah looked entirely different. Instead of desert, Grand Staircase–Escalante was home to a lush, tropical rainforest, where abundant plants supported an ecosystem of prehistoric giants. The monument is now known as the ‘Shangri-La of dinosaurs.’

Around 90 million years ago, during the Late Cretaceous period, rising seas inundated the middle of the country, splitting North America into two continents: Laramidia to the west and Appalachia to the east. All records of Laramidia, known as the “lost continent,” are buried under layers of rock and soil in the Western states. Paleontologists have only uncovered fossils from Laramidia in a handful of exceptional and heavily-eroded landscapes — like Grand Staircase–Escalante National Monument — but what they have unearthed has challenged long-standing assumptions about dinosaur evolution and revealed remarkable new species.

So far, paleontologists have found 25 unique species of dinosaurs in Grand Staircase–Escalante. The Kaiparowits formation and its predecessor, the Wahweap formation, have become a practical “treasure trove” of fossils revealing never-before-seen tropical plants, turtles, crocodiles, and dinosaurs. Laramidia, a continent one-fifth the size of Africa, was home to 15 to 20 rhinoceros- to elephant-sized species of dinosaurs likely thriving off the abundant resources of the tropical ecosystem — Grand Staircase–Escalante was home to many of them.

Meet the dinosaurs of Grand Staircase–Escalante National Monument.

Age: ~76 million years ago

Formation: Kaiparowits

Name: ornamented horned face (nickname: the “horny-est dinosaur ever”)

Size: 15 feet long, with a massive skull measuring at nearly 6 feet

Diet: Herbivore

Fun facts: Paleontologists think that Kosmoceratops 13-horned frill was used for intimidation or for attracting mates, not defense. According to paleontologist Scott Sampson, “The sideways-oriented horns offer another means to lock heads and engage in contests of dominance.” Whatever their purpose, it’s easy to see how Kosmoceratops earned it’s nickname — “horny-est dinosaur ever.”

Age: ~76 million years ago

Formation: Kaiparowits

Name: big-nose horned face

Size: 15 feet long

Diet: Herbivore

Fun facts: Both Nasutoceratops and Kosmoceratops are part of the “ceratopsid” family. All ceratopsids display pronounced nose regions, but Nasutoceratops’ oversized nose takes it to a new level. According to Sampson, “The jumbo-sized schnoz of Nasutoceratops likely had nothing to do with a heightened sense of smell — since olfactory receptors occur further back in the head, adjacent to the brain — and the function of this bizarre feature remains uncertain.”

Age: ~76 million years ago

Formation: Kaiparowits

Name: Utahceratops is named for its home state — Utah!

Size: 18–22 feet long, with a massive 7 foot skull

Diet: Herbivore

Fun facts: Utahceratops’ mouth contains hundreds of rows of column-like teeth, creating a “dental battery” used for slicing up tough plants. Because of the size of its massive 7 foot skull, Utahceratops’ horned frill at the top of its head is hollow to minimize its weight.

Age: ~80 million years ago

Formation: Wahweap

Name: devil, (nickname: the “Last Chance Ceratopsian”)

Size: 18 feet long

Diet: Herbivore

Fun facts: Diabloceratops’ is named for its devilish horns, but its nickname — the “Last Chance Ceratopsian” — comes from the Last Chance Stream where it was found. First discovered in 1998, Diabloceratops is the oldest-known member of the centrosaurine ceratopsian family and the first unearthed south of Montana.

Age: ~77 million years ago

Formation: Kaiparowits

Name: bent sword face

Size: 20–26 feet long

Diet: Herbivore

Fun facts: Macharioceratops’ unique hook-like horns earned it the name ‘bent sword face,’ but their purpose remains a mystery to scientist. Ohio University paleontologist Erik Lund says, “[It’s] a unique morphology unto itself, but there is also a groove on the big spikes, which is a characteristic not ever seen before in horned dinosaurs.” While it’s possible the hooks were a mating display feature or used for intimidation, their exact use is unknown.

Age: ~76 million years ago

Formation: Kaiparowits

Name: monstrous murderer

Size: 12 feet tall

Diet: Carnivore

Fun facts: Teratophoneus is the most complete Tyrannosaur fossil in the Southwest. So far, 80 percent of its skeleton has been unearthed, remarkably preserved in the position it died in. Despite its name, Teratophoneus was not nearly as monstrous as its relative Tyrannosaurus, the most famous member of the Tyrannosaur group. Based on the skeleton uncovered in Grand Staircase–Escalante, Teratophoneus was only about one-tenth of the size of the mighty Tyrannosaurus.

Age: ~80 million years ago

Formation: Wahweap

Name: king of gore

Size: 24 feet long

Diet: Carnivore

Fun facts: At approximately 80 million years old, Lythronax is the oldest known tyrannosaur. “Despite being the oldest known tyrannosaurid, it’s by no means a primitive member of the group,” says Corwin Sullivan of the Institute of Vertebrate Palaeontology and Palaeoanthropology in Beijing, “[That] tells us two interesting things: that tyrannosaurids started their evolutionary radiation sooner than we thought, and that a fair bit of their early record is still missing.”

Age: ~76 million years ago

Formation: Kaiparowits

Name: hooked beaked lizard

Size: 40 feet long

Diet: Herbivore

Fun facts: 76 million years ago, Gryposaurus was the largest known dinosaur in Utah, surpassing local tyrannosaurs. In fact, Gryposaurus was so large that Sampson has referred to it as the “Arnold Schwarznegger of duck-billed dinosaurs.” The second half of Gryposaurus’ name, monumentensis, is named for Grand Staircase–Escalante National Monument, where many monumental paleontological discoveries have been unearthed.

Age: ~75 million years ago

Formation: Kaiparowits

Name: near crested lizard

Size: 30 feet tall

Diet: Herbivore

Fun facts: Paleontologists believe that Parasaurolophus’ strange, tubular crest was likely used to attract mates. Fossils indicate that the crests of Parasaurolophus males were bigger than female crests. As Alan Titus, the Bureau of Land Management paleontologist at Grand Staircase–Escalante, says, “It’s about looking good and showing off.”

Age: ~76 million years ago

Formation: Kaiparowits

Name: Talos, which means talon in Greek, is named for a winged figure with lightning-fast speed from Greek mythology

Size: 6 feet long, 3 feet tall

Diet: Omnivore

Fun facts: The extremely rare Talos remains unearthed in Grand Staircase–Escalante gave paleontologists an unlikely window into Talos’ behavior. Because of a severe injury Lindsay Zanno, a paleontologist at The Field Museum of Natural History in Chicago, believes the dinosaur was likely “doing something dangerous, something high risk.” According to Zanno, “[The talon] was either used to hunt prey, or it was used in combat with other members of the species, which is something other modern birds do.” Paleontologists even suggest the talon may have been used as a puncture device, possibly to climb large prey or pin down smaller animals.