[1] The show features the reign of the non-avian dinosaurs in America over the course of more than 160 million years, through five different segments, each with their own variety of flora and fauna.
When Dinosaurs Roamed America premiered to 5 million viewers[2] and aired numerous times on the Discovery HD Theater's opening lineup in 2002.
[3] When Dinosaurs Roamed America was directed by Pierre de Lespinois[4] with Evergreen Films, and was narrated by actor John Goodman (voice of Rex in We're Back!
Unlike Walking with Dinosaurs, the show's creatures are almost entirely composed of computer-generated imagery, and is also one of the first documentaries to depict dromaeosaurs and therizinosaurs with nearly full coats of feathers.
[4] Exotic HD cameras were rare at the time, which made reaching some of the filming locations for When Dinosaurs Roamed America (which include various parts of Argentina, Tasmania, and Florida) difficult, but the portable HD cameras allowed de Lespinois and his small team to capture never-before-seen shots of the various landscapes.
When Dinosaurs Roamed America was first revealed on the Discovery website in June 2001, originally with a July 13 airdate set.
The narrator explains how the Permian mass extinction led to new forms of life, including, eventually, the most extraordinary creatures ever to walk the planet, the dinosaurs.
The Ceratosaurus feasts while the others escape into a grove of pine trees and run into a herd of sauropods called Camarasaurus.
The program then shows a forest located in New Mexico during the Middle Cretaceous period (all centering the Moreno Hill Formation).
Small predatory coelurosaurs, now identified as the tyrannosauroid Suskityrannus, scamper through the foliage and steal pieces of meat from a dead Zuniceratops.
Zuniceratops panic for safety and the Nothronychus follows, but the feasting dromaeosaurs are too distracted by eating and fire surrounds the region.
In the Late Cretaceous, near Mount Rushmore in South Dakota (specifically Bone Butte), Anatotitan and Triceratops browse on a rolling grassland bordered by tropical jungle, while Ornithomimus peck at roots and other plants in the area.
Unable to get past the horns of the defensive Triceratops, the Tyrannosaurus attacks a Quetzalcoatlus, but the pterosaur launches off and flies away from the hungry theropod.
The three Tyrannosaurus chase after one individual and it runs straight into the forest where the mother emerges from the bushes, grabs the unfortunate hadrosaur, and kills it by breaking its neck.
The impact gouges out a crater 120 miles wide and sends an incandescent plume of dust, glass and ash into the atmosphere which falls back to earth as fiery debris.
The feasting Tyrannosaurus watch in horror as a burning blast wave hurtles towards them and flee as pieces of fiery rock rain down.
A few hours after impact, a heavy cloud of dust and ash settles over America, and temperatures drop as sunlight and heat can no longer reach the surface of the planet.
Despite the depressing and traumatic event, life is described as being resilient, and a turtle is shown emerging from the water and a bird flies overhead, explained by the narrator as the only dinosaurs left.