Laramide orogeny prior to their extinction." This turnover event saw the replacement of specialized and highly ornamented centrosaurine and lambeosaurines by more basal upland dinosaurs in the south, while northern biomes became dominated by "Triceratops" with a greatly reduced hadrosaur community. Laramide orogeny The Laramide orogeny was a period of mountain building in western North America, which started in the Late Cretaceous, 70 to 80 million years ago, and ended 35 to 55 million years ago. The exact duration and ages of beginning and end of the orogeny are in dispute. The Laramide orogeny occurred in a series of pulses, with quiescent
Trans-Hudson orogeny Yavapai province (see Trans-Hudson Orogen map and the THOT Transect map. To the south, the orogen contributed to the subsurface Phanerozoic strata in Montana and the Dakotas that created the Great Plains. The Trans-Hudson orogeny was the culminating event of the Paleoproterozoic Laurentian assembly, which occurred after the Wopmay orogeny (West of Hudson Bay, ca. 2.1-1.9 Ga.). The Trans-Hudson orogeny resulted from the collision of the Superior Craton of eastern Canada with the Hearne Craton in northern Saskatchewan and the Wyoming Craton of the western United States, with the Archean microcontinent Sask Craton trapped in the THO western interior. Similar