"Hardwood forests are a common biome throughout the broader Hell Creek ecossystem, making up the majority of the floodplain habitat. Flowering plants had taken hold by the late Cretaceous and here the medium-sized walnut-like tree Dryophyllum dominates the canopy, with plane trees (Platanaceae) increasingly common around ponds and streams. Groups of Triceratops frequent this biome, browsing upon the abundant foliage. Using the denser forest edges as cover, the mighty Tyrannosaurus rex can also be found in this habitat, laying in wait of an ambush."

― Saurian encylopedia

The hardwood forest is a biome simillar to the bluffs, mainly because it contains a variety and abundance of the same vegetation, but the main difference between the two is that the hardwood forest has less elevations, which determines it's location close to the river, while the Bluffs are located at the edge of the map (not counting with the ocean). The vegetation of the hardwood forest is mainly composed by tall thin trees with large canopies, providing shade. The hardwood forest is obviously different from the cypress forests and redwood forests, as it contains mainly oak and willow looking trees, instead of being composed by conifers and other trees with wide trunks. This environment is shady and slightly bushy, which is perfect for the lurking Acheroraptor. Dakotaraptor usually wander these regions for food. Chamops and Palaeosaniwa are quite common, and Didelphodon are pretty common. Medium to small sized herbivores, like the ornithomimids, Denversaurus, Thescelosaurus and Pachycephalosaurus are sometimes found here, as well as the gigantic Tyrannosaurus. Ankylosaurus are seldomly found here.