While generally accurate for when it was made, it was over 15 years ago. New evidence of creatures that we can have no real idea on behavior, color and other details are always emerging. So, there are inaccuracies.
!'''Walking With Dinosaurs'''
!!In general
* Most [[StockDinosaursTrueDinosaurs coelurosaurs]] certainly had feathers. The several [[StockDinosaursTrueDinosaurs dromaeosaurid species]] surely had them, but in the franchise they are all shown featherless, see further): this, rather than ScienceMarchesOn, might be interpreted more as RuleOfCool, or rather, ArtisticLicensePaleontology, since feathered raptors would have appeared "too cute"? In RealLife dromeosaurids had WINGS just like their famous relative, the "ur-bird" ''[[StockDinosaursTrueDinosaurs Archaeopteryx]]'' This might be nothing compared to what is seeming to come: ''most small-sized dinosaurs'' may well have had some sort of covering. This is a very recent theory led by the discover of the primitive herbivore ''[[UsefulNotes/PrehistoricLife Tianyulong]]'' in China: the theory is that some kind of covering was present in the last common ancestor of ''all'' dinosaurs and pterosaurs, and then it was partially lost by its largest descendants, possibly because of the [[http://en.wikipedia.org/wiki/Surface-area-to-volume_ratio#Biology surface area to volume ratio]]. Some think the "spikes" on ''[[StockDinosaursTrueDinosaurs Diplodocus]]'' have the same common origin of feathers, as well as the quill of the small herbivore ''[[UsefulNotes/PrehistoricLifeHadrosaurPredecessors Psittacosaurus]]'' and even the horny bumps lined on the back of several [[StockDinosaursTrueDinosaurs hadrosaur mummies]]. See UsefulNotes/{{Dinosaurs}} for more infos about that. Whatever the case, the old "gigantic lizards" seem to have their days numbered now.
* They tried to partially remedy all the issues by showing ''Walking with Dinosaurs'' again in 2008 with updated narration. Unfortunately, the visuals remained untouched, so the small carnivore ''Ornitholestes'' still had a horn, coelurosaurs were still scaly, so on and so forth.
* Any and all shots of pterosaurs taking off bipedally became inaccurate after it was discovered that they launched quadrupedally.
* All the non-avian theropods have pronated hands, a position that is impossible in reality.

!!''New Blood''
* What was thought to be evidence for "cannibalistic ''[[StockDinosaursTrueDinosaurs Coelophysis]]''" has been discredited.
* As the now-synonymous ''[[UsefulNotes/PrehistoricLifeOtherSmallTheropods Megapnosaurus]]'' indicates, ''Coelophysis'' was nocturnal.
* The early long-necked dinosaur ''[[StockDinosaursTrueDinosaurs Plateosaurus]]'' could not walk on four legs.
* The pillar-limbed croc-relative ''[[UsefulNotes/PrehistoricLifeNonDinosaurianReptiles Postosuchus]]'' was most likely a biped, or at least semi-bipedal, rather than an obligate quadruped. It would be a pursuit predator, not a slow ambush predator.
* There were no [[UsefulNotes/PrehistoricLifeNonDinosaurianReptiles cynodonts]] of the size depicted in the program in the late Triassic[[note]]other than traversodonts. Given that some Mesozoic mammals reached similar sizes (such as the infamous ''Repenomamus''), cynodonts that big in that time period aren't strictly unlikely, but unknown from the area the episode took place[[/note]]. This is an example of ScienceMarchesOn rather than ArtisticLicensePaleontology because at the time the series was produced it was assumed that cynodonts of that size did live in Late Triassic in North America. This assumption was based on the discovery of [[http://chinleana.blogspot.com/2009/09/enigmatic-triassic-taxa.html two teeth]] from [[http://en.wikipedia.org/wiki/Chinle_Formation Chinle Formation]][[note]]though these teeth were assumed to belong to [[http://en.wikipedia.org/wiki/Traversodontidae traversodont]] cynodonts, much different from ''Thrinaxodon'' that WWD-cynodonts were based on[[/note]]. However, [[http://socrates.berkeley.edu/~irmisr/chinleteeth.pdf post-WWD study]] indicate that these teeth can't be confidently referred to Cynodontia (or any other known group of Triassic amniotes, for that matter).

!!''Time of the Titans''
* ''Allosaurus'' was only one-fourth the size it was depicted. This may have resulted from confusion with a close relative called ''Saurophaganax'' which actually did grow to 6 tons and was at one point considered a synonym of its smaller cousin.
* Sorry, ''[[UsefulNotes/PrehistoricLifeOtherSmallTheropods Ornitholestes]]'', you didn't actually have that horn-thing on your nose. The nasal bones in your otherwise impressive type skeleton were broken and flattened during fossilization.
* Recent studies suggest that ''[[UsefulNotes/PrehistoricLifeNonDinosaurianReptiles Anurognathus]]'' and its ilk were nocturnal and caught insects on the fly, like bats or swifts, making the "Mesozoic oxpecker" idea presented on the show highly unlikely.
* Post-WWD studies indicate that [[StockDinosaursTrueDinosaurs sauropod dinosaurs]] probably didn't grow to adult size within more or less ten years as shown in the series, although exactly how fast they grew is still debated (current estimates range from [[http://dx.doi.org/10.1111/j.1469-185X.2010.00137.x less than four decades]] to [[http://paleobiol.geoscienceworld.org/cgi/content/abstract/34/2/264 up to 70 years of growth]] necessary to reach maximum adult size).
* The idea that sauropods could only hold their necks horizontally - which influenced the WWD reconstructions of ''[[StockDinosaursTrueDinosaurs Diplodocus]]'', ''[[StockDinosaursTrueDinosaurs Apatosaurus]]'' and ''[[StockDinosaursTrueDinosaurs Argentinosaurus]]'', which in turn probably popularized the concept - [[http://app.pan.pl/archive/published/app54/app54-213.pdf is questioned nowadays as well]].
* "Iguana-spike-backed" ''Diplodocus'': Some researchers now argue these spikes were spread across on ''Diplodocus''' back rather than put in a single line as shown in the program.
* [[http://www.sciencedaily.com/releases/2010/11/101101083150.htm Footprints from a baby bipedal sauropod]] have been recently found: Perhaps [[WesternAnimation/TheLandBeforeTime Littlefoot]] and the WWD sauropodlets ''walked on two legs'' and become quadrupedal only when they grew larger (an ancient heritage from their ancestors, the "prosauropods" such as the aforementioned ''[[StockDinosaursTrueDinosaurs Plateosaurus]]'')! However, most paleontologists are skeptical of this interpretation. Even the trackways of adult sauropods often leave just the prints from just one pair of feet, thus is even more likely about the younger ones.
* ''Brachiosaurus'' is no longer considered the largest land animal; the exact species of sauropod that was is not clear but it wasn't ''Brachiosaurus''.
* Evidence suggests that ''Stegosaurus'' lived in herds and would have preferred the open savanna regions of the Morrison formation to the more forested areas. Also, [[http://scienceblogs.com/tetrapodzoology/2011/01/10/stegosaur-skin-plates-sex/ a study on stegosaur skin impression]] suggests the plates were covered in horn rather than skin, making the scene where the ''Stegosaurus'' reddens its plates by flushing blood into them unlikely.

!!''Cruel Sea''
* Biomechanical studies have shown that skim feeding (as ''Rhamphorhynchus'' is shown doing) was not possible in known pterosaurs. ''Rhamphorhynchus'' itself is more likely to have hunted fish while swimming and diving.
* [[StockDinosaursNonDinosaurs Plesiosaurs]] [[http://dx.doi.org/10.1126/science.1205689 gave birth to alive newborns]] just like the fish-like [[StockDinosaursNonDinosaurs ichthyosaurs]]; and they perhaps could not crawl onto land because the shape of their chest.
* ''Rhamphorhynchus'' has since been found to likely have been nocturnal.
* Evidence of pliosaurs as large as the one in the episode has now been discredited. The largest known pliosaurs were probably "only" around 15 metres or so at the most. The fragmentary remains initially identified as that of ''Liopleurodon'' are now regarded as an unknown and yet unnamed genus. ''Liopleurodon'' itself was only about 21 feet long.
* ''Ophthalmosaurus'' could actually give birth to more than five pups at a time; apparently at least eleven.

!!''Giant of the Skies''
* The ''[[UsefulNotes/PrehistoricLifeNonDinosaurianReptiles Tapejara]]'' species featured has now been reassigned to ''Tupandactylus''. We also now know that the head is too small and the males had a flat crest rather than a ridged crest.
* The giant ''[[UsefulNotes/PrehistoricLifeNonDinosaurianReptiles Ornithocheirus]]'' was based on a specimen now assigned to ''[[UsefulNotes/PrehistoricLifeNonDinosaurianReptiles Tropeognathus]]''. Though it was indeed very large for an ornithocheirid, the show chose high-end, improbable estimates for its stated size. In reality, the specimen probably had around an 8m wingspan. Additionally, the claim that ''Ornithocheirus'' would have to keep himself dry at all times in order to fly has also been proven wrong, as there is now substantial evidence to suggest that ornithocheirid pterosaurs were actually quite good at swimming.
* The "American ''[[StockDinosaursTrueDinosaurs Iguanodon]]''" from the fourth episode would probably be placed in the genus ''[[http://dx.doi.org/10.1016/j.cretres.2007.04.009 Dakotadon]]'' today.
** It's doubtful the European ''Iguanodon'' was actually ''Iguanodon'' and not, for example, ''Mantellisaurus'', ''Hypselospinus'' or ''Barilium''.
* Most enantiornithines are now known to have lacked tail fans, contrary to the ''Iberomesornis'' shown in the series. Some enantiornithes also seem to have 2 long feathers at the end of the tail, which the birds in the show lack. Known enantiornithines nests show that they also nested on the ground.

!!''Spirits of the Ice Forest''
* Some argue that ''[[UsefulNotes/PrehistoricLifeHadrosaurPredecessors Leaellynasaura]]'' needs plumage.
* The "dwarf allosaur" seen in this episode may or may not be the theropod now known as ''Australovenator''. It actually wasn't an exact scaled-down version of the North American ''Allosaurus''. It was the size it was depicted and had longer arms with devastating claws.
** If the dwarf allosaur was indeed ''Australovenator'' then it may not be an allosaur at all, as some evidence suggests megaraptorans (the group of which ''Australovenator'' belongs) are coelurosaurs, even ''tyrannosaurs''.

!!''Death of a Dynasty''
* The evidence for female ''[[StockDinosaursTrueDinosaurs Tyrannosaurus]]'' being larger than males is inconclusive at best, although considering that this pattern of dimorphism is seen in most large carnivorous birds as well as the most primitive birds today, it isn't exactly improbable.
* The [[PteroSoarer giant pterosaur]] ''[[StockDinosaursNonDinosaurs Quetzalcoatlus]]'' is shown as a fish eater hunting prey on the wing, while we now know it was actually stork like in habits. In fact, it probably wouldn't have hesitated to eat juvenile tyrannosaurs, like the ones in the program! We now know ''Quetzalcoatlus'' actually had a much larger head and neck.
** Additionally, pterosaurs were probably ''not'' "on the decline" at the end of the Cretaceous. Indeed, Azhdarchids like ''Quetzalcoatlus'' were among the most successful animals at the time. And in 2016, it was discovered that there were other pterosaurs aside from azhdarchids likely made it to the end of the Cretaceous (pteranodontids and nyctosaurids specifically) and that not all late Cretaceous pterosaurs were giants (an as of late unnamed azhdarchid was discovered from this time, and it was only the size of a cat).
* It's [[http://www.newscientist.com/article/mg20727713.500-morphosaurs-how-shapeshifting-dinosaurs-deceived-us.html been theorized]] that ''[[StockDinosaursTrueDinosaurs Triceratops]]'' and ''[[UsefulNotes/PrehistoricLifeCeratopsids Torosaurus]]'' (which were featured in ''Death of a Dynasty'' as seperate genera) are actually the same animal in different growth stages. However, research on this is still ongoing and has been doubted by some [[http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0032623 recent studies.]]
* The accompanying book briefly mentions the possibility that ''[[StockDinosaursTrueDinosaurs Anatotitan]]'' is synonymous with ''[[StockDinosaursTrueDinosaurs Edmontosaurus]]''. As of September 2011, this is the majority view.
* A full ''Didelphodon'' skeleton found in an ancient riverbed shows a slender, long-tailed otter-like animal with aquatic adaptations, different from the compact badger/wolverine/opossum-like oportunistic carnivore seen in the series. The strong jaws and teeth (i.e. what was basically known of ''Didelphodon'' before this discovery) might have been an adaptation to crush freshwater molluscs.
!'''Walking With Beasts''':
!!''New Dawn''
* Debatable with the brief shot of a tamandua, likely meant to represent ''[[UsefulNotes/PrehistoricLifeMammals Eurotamandua]]'' from the Eocene of [[http://en.wikipedia.org/wiki/Messel_pit Messel]], which was initially identified as an anteater. More recent studies indicate that it probably wasn't an anteater [[http://scienceblogs.com/tetrapodzoology/2010/03/the_anteater_that_isnt.php and quite likely it wasn't a xenarthran at all]]. However, the alternative is that it was a primitive, arboreal pangolin with no armor. This makes sense (since anteaters originated in South America while pangolins appeared in Eurasia, and other pangolins are known in Europe at this time) but also means that ''Eurotamandua'', in the flesh, would look very much like a tamandua even if it wasn't a real tamandua. The use of a tamandua as a stand-in should be perfectly excusable. The use of a coati as a stand-in for the giant platypus ''[[UsefulNotes/PrehistoricLifeMammals Steropodon]]'' in WWD, on the other hand... not so much.
* Whether the robust beak of ''Gastornis'' was to crush large nuts or small animals has been a matter of debate since its discovery. WWB went with the animals and presented ''Gastornis'' as the top predator in the Eocene European jungle. However, the latest study on calcium isotopes found that ''Gastornis''' data was more similar to herbivorous mammals and reptiles (such as dinosaurs). There goes the show's iconic line about the Eocene being a time when birds ate horses. More likely terrestrial crocodilians such as ''Boverisuchus'' would have been the apex predators.
* It's not completely agreed up whether leptictids hopped like modern kangaroos, or walked bipedally like theropod dinosaurs. A close relative of ''Leptictidium'', ''Leptictis'' is currently believed to have walked rather than hopped, but differences between the skeletons make it insufficient evidence to suggest either way for ''Leptictidium''.
* ''Ambulocetus'' most likely [[https://www.sciencedaily.com/releases/2016/07/160725105228.htm couldn't support itself on land]].

!!''Whale Killer''
* ''[[UsefulNotes/PrehistoricLifeMammals Andrewsarchus]]'', known only from the skull and a few fragments of bone, was assumed at the time the series was produced to be closely related to [[UsefulNotes/PrehistoricLifeMammals mesonychids]], and modeled after them. However, [[http://scienceblogs.com/tetrapodzoology/2009/08/13/mesonychians-part-iii-andrewsa/ later]] [[http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0007062 phylogenetic studies]] indicate that it might have actually been a close relative of [[UsefulNotes/PrehistoricLifeMammals entelodonts]].
** And on that note, mesonychids most likely weren't the true ancestors of whales. Later studies have found whales to still be ungulates, but closer to the ancestors of hippopotamuses than more basal groups like the mesonychids.
* ''Basilosaurus'' was a shallow-water predator, while the show had it as being forced into shallow water from the open sea.

!!''Next of Kin''
* While not entirely conclusive, the results of a 2002 study on the calcium isotopes of fossil carnivores that lived alongside australopithecines found that their sample of ''Dinofelis'' was typical of an animal that fed solely on grass-eating animals like large ungulates, and not omnivores like primates. However, the same study did find that the smaller sabertoothed cat ''Megantereon'' sometimes ate omnivores, and a skull of ''Homo georgicus'' from Dmanisi has bite marks of ''Megantereon''. So even if ''Dinofelis'' didn't hunt hominids, we have at least proof that other sabertoothed cats did.
* The ''Deinotherium'' model subscribes to the theory that deinotheres had shorter trunks than elephants. This was based on the fact that deinotheres separate early from the proboscidean family tree, and that their skulls lack the attachment marks corresponding to some trunk muscles, which were interpreted as deinotheres lacking these muscles, and as a result having shorter and more primitive trunks. It has been later found that ''elephants'' don't have these marks either, because the muscles attach to other muscles in the trunk rather than the skull. If deinotheres didn't have them, it could be because they had long, advanced, elephant-like trunks, rather than the opposite. Finally, authors of the later study appealed to common sense: while deinothere necks are slightly longer than elephant's, their legs are also longer, and they are not better at kneeling than elephant legs are. This means that if deinotheres [[http://img4.wikia.nocookie.net/__cb20111003161259/dinosaurs/images/5/5c/Deinotherium.jpg had trunks as short as proposed]], the animals would be almost unable to drink.

!!''Sabre Tooth''
* ''Smilodon'' was a terrible runner and would not be able to chase prey in the manner shown, or even at all.
* If ''Smilodon'' lived in packs, they would likely not have a lion-like structure (1-2 or so males with a lot of females), due to males and females being similar sizes. Wolf-like packs have been suggested (1 main male/female pair, with a mixed group of other members), although the evidence for any sort of pack is thin.
* The species of ''Smilodon'' shown in the episode had not evolved yet when the show was set.

!!''Mammoth Journey''
* Ancient DNA studies have found that Europeans retained dark skin tones until the arrival of paler people [[HilariousInHindsight from the Middle East and Siberia]] about 7,000 years ago. This means the episode's ''Homo sapiens'' should be of darker complexion than the neanderthals.
* The interpretation of the Jersey cliffs as killing sites where neanderthals drove mammoths over the edge and butchered them bellow has been [[http://antiquity.ac.uk/ant/088/ant0880013.htm questioned]]. The mammoth bones might have just rolled downhill and accumulated there naturally, long after their owners died.
!'''Walking With Monsters''':
* Arthropods DO have brains, DO use them and CAN think, contrary to what the show explicitly stated.
* The [[UsefulNotes/PrehistoricLifeOtherExtinctCreatures Giant Spider]] in the Carboniferous was based on ''Megarachne'', which ultimately turned out to be [[UsefulNotes/PrehistoricLifeOtherExtinctCreatures eurypterid]] ("sea scorpion") rather than spider.
* The lineage that gave rise to mammals split to the one that gave rise to reptiles and birds before those developed the reptilian scales. The show represents perhaps the first time that ''[[StockDinosaursNonDinosaurs Dimetrodon]]'' and its herbivorous "twin" ''[[UsefulNotes/PrehistoricLifeNonDinosaurianReptiles Edaphosaurus]]'' have skins similar that of modern hairless mammals, instead of the classic scaly one. However, some think now that they would have the skin texture of a salamander, and the belly of a fish.
** Surprisingly, ''Dimetrodon'' may have been nocturnal.
** Interesting to note that the giant, AngryGuardDog-looking [[UsefulNotes/PrehistoricLifeNonDinosaurianReptiles Gorgonopsid]] from the show has scent glands (a typical mammalian feature).
* The armoured plant-eating near-reptile ''[[UsefulNotes/PrehistoricLifeNonDinosaurianReptiles Scutosaurus]]'' wasn't probably the ancestor of turtles. Recent research suggests that the latter were closer to modern reptiles than to ''Scutosaurus''.
* ''Euparkeria'' wasn't anything close to the "dinosaur ancestor" that the program makes it out to be. Not only did it evolve its bipedal gait independently from dinosaurs, it was more related to basal archosaurs, a group containing multiple major groups of reptiles other than dinosaurs. It was equally as related to crocodiles and pterosaurs as it was to dinosaurs.
!'''Chased by Dinosaurs''':
!!''Land of Giants''
* This special portrayed the largest land animal of all time, ''[[StockDinosaursTrueDinosaurs Argentinosaurus]]'', being hunted by the largest land predator, ''[[StockDinosaursTrueDinosaurs Giganotosaurus]]''. Both have been supplanted since then: New evidence found that ''[[StockDinosaursTrueDinosaurs Spinosaurus]]'' was the biggest land predator (though it was partially aquatic), while ''Argentinosaurus'' has been surpassed slightly in length by 2006-described ''Turiasaurus'' (''Argentinosaurus'' is still heavier, though).[[note]]Even before ''Argentinosaurus'' was described its estimated size and weight was surpassed by those attributed to ''Amphicoelias'' and ''Bruhathkayosaurus''. However, the record size of ''Amphicoelias'' was based on a single partial vertebra that was lost shortly after it was described by Cope in 1878, and the estimated dimensions of ''Bruhathkayosaurus'' were never peer-reviewed and published (and since the type fossil was later lost in a moonsoon flood, no further study can be made on it). The accuracy of both original descriptions has been questioned.[[/note]]
* Subsequent stratigraphic studies have shown that ''Giganotosaurus'' did not live at quite the same time as ''Argentinosaurus'', although a close relative, ''Mapusaurus'', did. That said, they did still live close enough together in time that some overlap could still be possible.
** There is also no evidence that ''Giganotosaurus'' hunted in packs, although there is some indication that ''Mapusaurus'' did.
* A biomechanical study cast doubt on the ability of ''Sarcosuchus'' to roll over like modern crocodiles. Though the authors are cautious in this regard, the implication is that ''Sarcosuchus'' was a strict fish eater and did not attack drinking animals on the shore, like modern gharials (similarly long snouted). ''Deinosuchus'', seen in WWD and ''Prehistoric Park'', did not have such problems.
* The South American ''Iguanodon'' is now named ''Macrogryphosaurus''.
* Later studies suggest that ''Pteranodon'' caught fish by diving into the water and swimming for their prey rather than snatching it up on the fly.

!!''The Giant Claw''
* Feather issues aside, ''Velociraptor'' was likely nocturnal.
* No trace of ''Therizinosaurus'' skin has been found, but the fact that its human-sized relative ''Beipiaosaurus'' had a complex feather cover makes it likely that ''Therizinosaurus'' had one too. The result looks like a cross between a goose and a ground sloth, much different from the show's naked model.
!'''Sea Monsters''':
* The enormously long-necked ''[[UsefulNotes/PrehistoricLifeNonDinosaurianReptiles Tanystropheus]]'' was potrayed as capable of losing and regenerating its tail like a lizard. In the past it was indeed suggested by palaeontologist Rupert Wild[[note]]who also thought that ''Tanystropheus'' was closely related to lizards - nowadays it's generally considered to be more closely related to archosaurs than to lizards[[/note]] that this creature was capable of autotomy, but other scientists who studied its fossils didn't find evidence for that. It has also been portrayed as an accomplished swimmer, but [[http://markwitton-com.blogspot.ca/2015/11/the-lifestyle-of-tanystropheus-part-1.html we don't know for sure if it really was such]] - its body-shape was all but hydrodynamic, and some think ''Tanystropheus'' [[http://markwitton-com.blogspot.ca/2015/12/the-lifestyle-of-tanystropheus-part-2.html was a shore animal who used its neck as a fishing rod]], catching small prey a bit like a heron. Interestingly, the very similar ''Dinocephalosaurus'', which probably was a true swimmer, was discovered the same year the special premiered.
* In the accompanying book there is a DeletedScene where female [[UsefulNotes/PrehistoricLifeNonDinosaurianReptiles nothosaurs]] (primitive Triassic sea reptiles related to the more famous [[StockDinosaursNonDinosaurs plesiosaurs]]) leave their eggs on the beach at night (see WhatCouldHaveBeen on the Trivia page). However [[http://www.nature.com/nature/journal/v432/n7015/full/nature03050.html it turns out that nothosaurs might have been viviparous]].
* The show was made in 2003, and as a result missed out on the discovery of ''[[http://en.wikipedia.org/wiki/Livyatan_melvillei Livyatan melvillei]]''. Its fossil was discovered in the same area as the ''C. megalodon'' episode, and had they set it just a bit earlier, both of these monsters would have appeared. Also of note is the fact that period had even more large marine carnivores than the Cretaceous.
* A number of mosasaur fossils have been found with shark like tail impressions (one long fin, one short fin). These fossils, and various other arguments, suggest that most or all mosasaurs would have looked more fishlike than the ones shown on the show.
!'''The Complete Guide to Prehistoric Life:'''
* ''[[UsefulNotes/PrehistoricLifeHadrosaurPredecessors Othnielia]]'' and ''[[UsefulNotes/PrehistoricLifeHadrosaurPredecessors Leaellynasaura]]'' do not appear to be ornithopods, but more primitive ornithischians.
* Page 122 claims that [[UsefulNotes/PrehistoricLifeBirdlikeTheropods therizinosaurs]] are known from "a lone species" from North America, probably referring to ''[[UsefulNotes/PrehistoricLifeBirdlikeTheropods Nothronychus]]''. Enter the ancestral therizinosaur ''[[UsefulNotes/PrehistoricLifeBirdlikeTheropods Falcarius]]'' in 2005...
* To quote page 125, "Scientists cannot agree on whether ''[[UsefulNotes/PrehistoricLifeBirdlikeTheropods Mononykus]]'' was a bird or a [non-bird] dinosaur." The 2010 discovery of the ancestral alvarezsaur ''[[UsefulNotes/PrehistoricLifeBirdlikeTheropods Haplocheirus]]'' confirms that ''Mononykus'' and other alvarezsaurs were not birds.
* There actually isn't any evidence that terror birds like the ''Phorusrhacos'' in the program had meathook claws on their wings. That idea came from an observation that one species, ''Titanis'', had a very rigid wrist, suggesting the presence of some kind of digit. In 2005 it was pointed out that the birds' closest living relatives, seriemas, have the very same wrist, but no claws of any kind. However, seriemas ''do'' have a dromaosaur-like "[[https://upload.wikimedia.org/wikipedia/commons/5/51/Seriamanail_%28high_res%29.jpg sickle claw]]" on their second toe, suggesting that terror birds may have had that instead. It should also be noted that [[http://scienceblogs.com/tetrapodzoology/2010/06/30/clubs-spurs-spikes-and-claws/ most birds]] do have some kind of claw or spur hidden under their wing feathers, but nothing like the flexing, slashing finger shown in the book's restoration.
* ''Entelodon'' was not as closely related to pigs as was believed. It is now thought to be closer to whales and hippos.
!'''Walking with Dinosaurs 3D:'''
* Just after they finished the ''Gorgosaurus'' models, ''Yutyrannus'' (a feathered tyrannosaur) was found.
* ''Mere days'' before the movie premiered, it was discovered that ''[[StockDinosaursTrueDinosaurs Edmontosaurus]]'' had a small fleshy crest on its head.