'''''When Dinosaurs Roamed America''''' (2001, sometimes shortened to ''When Dinosaurs Roamed'', especially outside North America) was the Creator/DiscoveryChannel's first major attempt to [[FollowTheLeader cash-in]] on the [[EverythingsBetterWithDinosaurs dinosaur]]-[[{{Documentary}} documentary]] trend started by [[Creator/TheBBC BBC]]'s famous ''Series/WalkingWithDinosaurs''. Similar to that program, this also aimed for a SpeculativeDocumentary format, and used {{CGI}} to recreate its dinosaurs, [[UsefulNotes/PrehistoricLifeNonDinosaurianReptiles pterosaurs, and various other prehistoric animals]], placing them into [[RogerRabbitEffect real-life]] scenery. The stories were told in chronological order, from the beginning to the end of the dinosaurs' reign.

Unlike its predecessor/competitor, however, ''WDRA'' included short cut-away scenes to paleontologists and at times froze the animation to reveal the skeletal structure behind the animals' skin, using solid facts to [[ShownTheirWork explain the science]] that went into creating the program.

Other things that make it different from ''WWD'' is the fact that it concentrates purely on [[CaptainObvious American dinosaurs]], and condenses its stories into small segments, instead of devoting full episodes to them.

While disliked by some due to how quickly Discovery churned it out after hearing of the dinosaurs' marketability from Britain, the product was generally well-received by the viewers, especially compared to some later works, such as ''Series/ClashOfTheDinosaurs'' and ''Series/MonstersResurrected''.
!!The work contains examples of the following tropes:

* AllThereInTheManual: Notice that small, unnamed theropod from the very beginning of the last segment? The website reveals it's TheCameo of ''Ornithomimus''.
* AlwaysABiggerFish: ''Allosaurus'' to ''Ceratosaurus''. Also counts as an example of TheHunterBecomesTheHunted.
** The ''Megapnosaurus'' (''Kayentavenator''?) suddenly cease their attack on the ''Anchisaurus''. It turns out that the ''Dilophosaurus'' has shown up.
* AnimalsNotToScale: Most likely the result of the animators not paying attention. When the first ''T. rex'' shows up, it doesn't seem out of scale with the rest of the animals. But the narration claims it's a ''juvenile''. Later, when his mother appears, she is hulking huge, even compared to the "Anatotitan" which is supposed to be the same size as a ''rex''!
** Similarly ''Megapnosaurus'' is said to be 10 feet long; how come the not-even 7 foot ''Anchisaurus'' is more than twice their size (this could be a case of ScienceMarchesOn as the larger ''Ammosaurus'' is sometimes considered ''Anchisaurus'')?
* ApocalypseHow: A ApocalypseHow/{{Class4}} event at the end of the Cretaceous, but interestingly, the documentary also ''starts'' with an even larger meteor-strike, that was supposed to represent the great extinction event that ended the Permian and made way for the evolution of dinosaurs in the Triassic. A lesser meteor-related extinction also separates the Triassic and Jurassic.
** ApocalypseWow
* BewareMyStingerTail: ''Stegosaurus'' and ''Desmatosuchus''.
* EagleLand: Back when eagles still had teeth.
* EatsBabies: ''Ceratosaurus''.
* EverythingsBetterWithDinosaurs
* FailedASpotCheck: The deinonychosaurs fail to notice a forest fire, even when being surrounded by flames.
** BehindTheBlack: And the ''Ceratosaurus'' doesn't notice the hulking huge, oncoming ''Allosaurus'' either, until it's right on top of it. To the ceratosaur's credit, though, it ''was'' off-screen, even if out in the open, plainly visible from all sides.
* FamilyUnfriendlyDeath: What happens to the poor ''Apatosaurus'' that trips and falls.
* FeatheredFiend: The documentary famously depicted many dinosaurs with feathers, including "raptors" and the bizarre-looking ''Nothronychus''.
* ForegoneConclusion: The extinction at the end of the Cretaceous period.
* GiantFlyer: ''Quetzalcoatlus''.
* HemisphereBias: It's in the title.
* TheHunterBecomesTheHunted: ''Allosaurus'' does this to ''Ceratosaurus''.
* InfantImmortality: Averted, the ''Ceratosaurus'' catches a juvenile ''Dryosaurus''.
* MightyRoar: ''Tyrannosaurus'', obviously, but ''Dilophosaurus'' also has an awesome roar (which sounds oddly metallic).
* {{Narrator}}: John Goodman.
* NeverSmileAtACrocodile: Averted by the herbivorous ''Desmatosuchus'', but the (likely) non pseudosuchian ''Rutiodon'' does the job.
* NoPronunciationGuide: ''Desmatosuchus'' and ''Anatotitan'' are mispronounced "De'''mas'''tosuchus" and "Ana'''ta'''totitan", respectively.
** Dubs fared no better. For instance all three Hungarian narrations (yes, there's that many) had trouble deciding where to use soft "C"s and hard "K"s, which lead to mispronunciations like "Koelophysis", "Keratosaurus" and "koelurosaurus" -- on the other hand, the third version got ''Desmatosuchus'' right for once.
* NoisyNature: For a dinosaur-show, this is almost prerequisite. A particularly glaring example is the Dilophosaurus. Justified in the part where the Syntarsus ([[ScienceMarchesOn now Megapnosaurus]]) steal his food, since he is trying to scare them away, but for the most part he can't seem to shut up even when he's stalking prey (Ironically, ScienceMarchesOn and it is fairly certain most dinosaurs were not incredibly noisy animals).
* PrehistoricMonster: Avoided, although the animals do behave as aggressive as its intended audience expects them to.
* PteroSoarer: The ''Quetzalcoatlus'' may seem outdated by today's standards, but that's the result of [[ScienceMarchesOn science marching on]].
* RaptorAttack: Somewhat {{justified|Trope}}, as the {{CGI}} team couldn't get their feathers to be quite as birdlike as they should be.
* RealIsBrown: Practically all the animals are shades of brown.
* RogerRabbitEffect: The CGI creatures are dropped into RealLife scenery.
* ScreamsLikeALittleGirl: The ''Ceratosaurus'', as the ''Allosaurus'' kills it.
* SeldomSeenSpecies: ''Desmatosuchus'', ''Icarosaurus'', ''Rutiodon'', ''Anchisaurus'', ''Camarasaurus'', ''Nothronychus'', and ''Zuniceratops''.
* SexyDiscretionShot: When the ''Stegosaurus'' pair get ready to mate, the camera tilts skywards. This was the only solution, though: we don't really know just ''how'' they did it.
* ShownTheirWork: The scenes of paleontologists inserted in between the dinosaur clips.
** Feathered raptors and therizinosaurs.
* SmallTaxonomyPools: Averted. Many stock creatures appear, but so do a number of animals that have rarely ever been shown on television, notably the (then) newly-discovered ''Nothronychus'' and ''Zuniceratops'', as well as yet undescribed and unnamed [[http://www.arizonamuseumofnaturalhistory.org/exhibits/dinohall/theropods.aspx Zuni]] [[http://discovermagazine.com/2001/aug/featzuni coelurosaur]].
* SpeculativeDocumentary
* StockDinosaurs: ''Coelophysis'' in the Triassic (the only dinosaur in that segment), along with ''Allosaurus'', ''Apatosaurus'', ''Stegosaurus'', ''Ceratosaurus'' and ''Dilophosaurus'' from the Jurassic and ''Tyrannosaurus'', ''Triceratops'', "Anatotitan", and ''Quetzalcoatlus'' from the Cretaceous.
* TooDumbToLive: The dromaeosaurid attacking the ''Nothronychus'' head on, although both survive the attack. They then die when they're burned alive because they were too busy eating to run away from the fire.
* TyrannosaurusRex: The arguable "star" of the final segment.
* WolverineClaws: ''Nothronychus''.