Sauropelta

A flock of Deinonychus dart from the dense forest they had been moving through across the broad floodplain to the tree line on the far side.

- Phil Hore

Although highly intelligent and dangerous, the sheer size and thick-armored skin of the numerous dinosaurs feeding along the waterway afford these herbivores the luxury of barely registering the movement of the small predators.

Short and squat bodied, these nodosaurs slowly march along, with their heads lowered and swinging back and forth as they feed. Each animal keeps its distance from the next because of the large cone-shaped bony spears projecting from their shoulders.

Broad feet with thick webbing between the toes allow these heavy animals to move across the wet, slick mud that makes up the floor of the flood plain. Here they feed on the rich plant life—such as young seedling cycads and conifers—that sprout along this fertile region.

Not too far in the future this waterway will expand until it covers much of central North America, splitting the continent into two separate landmasses, but that’s a problem for the descendants of these early ankylosaurs. Today it’s a rich region full of life, all surviving off the occasional floods washing sediments in from the interior of the continent, turning the braided river plain into a roaring torrent of death and destruction.

This is the last time that many of the original American dinosaur species dominate the land because the future will belong to invasive species from Asia. Dinosaurs like the tyrannosaurs and ceratopians—groups that would evolve into iconic species like T. rex and Triceratops—would slowly replace the allosaurs, stegosaurs, and sauropods of the Jurassic.