拉腊米迪亚古陆，是距今大约9000-7000万年前的白垩纪晚期，一内路海道将现在的北美洲西部隔离为一块小型大陆。

科学家注意到，在拉腊米迪亚大陆的南北部似乎同时住着许多不同类型的大型恐龙，包括各式各样的角龙科以及暴龙科恐龙，虽然批评者对于此地的土地面积和食物数量是否能够同时供养如此多样的大型动物表示怀疑，但最近在大阶梯-埃斯卡兰特国家公园的凯帕罗维兹地层挖掘出的化石中发现了以往未知的恐龙群，巩固了其理论。

Laramidia was an island continent that existed during the Late Cretaceous period (99.6–66 Ma), when the Western Interior Seaway split the continent of North America in two. In the Mesozoic era, Laramidia was an island land mass separated from Appalachia to the east by the Western Interior Seaway. The seaway eventually shrank, split across the Dakotas, and retreated towards the Gulf of Mexico and the Hudson Bay. The masses joined to unite the North American continent.