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Despite Walking with... being a documentary series, several paleontological inaccuracies appear throughout some of the shows. However, most of the errors are caused by newer and more recent discoveries. Here's a list of them.

A scaly Velociraptor, an example of scientific inaccuracy in the Walking with series

Walking with Dinosaurs Pilot

Walking with Dinosaurs

New Blood

  • In the beginning, the narrator states that there was no grass in the Cretaceous. Some putative grass microfossils actually were recovered since the Albian stage of the Cretaceous, however they might instead just represent basal relatives to true grasses. Regardless, true grasses are known to have existed during the Late Cretaceous, thanks to phytoliths from the Indian Lameta Formation, dating to the Maastrichtian stage. Despite grasses having been around in the Late Cretaceous period, it wasn't as widespread as it is today, and, to date, little to no evidence exists on their presence in North America at the time.
  • There is slight shrink wrapping on the heads of Coelophysis, Postosuchus, and Plateosaurus. In reality, the skull openings likely were not externally visible.
  • There is no conclusive evidence that Coelophysis was cannibalistic. This was based on a fossil of Coelophysis with jumbled-up bones in its stomach cavity, but these turned out to be species of small crocodylomorphs, rather than the juveniles they were long mistaken to be. However, this was discovered after the release of this episode, and it is not implausible, given that cannibalism is not rare in theropods.
  • Coelophysis may have had feathers, but this is still highly debated. Recently a study on thermoregulation of Triassic ornithodirans confirmed that Coelophysis would likely have a body completely covered in feathers, as much as any other smaller ornithodirans at the time. However, another study that aimed to calculate the body heat generated in comparison to the size of the body of different types of animals, showed that this correlation isn't always crescent and might have been highly variable in animals, including extinct ones. When translated to ornithodirans, this would ideally not be detrimental for smaller species to endure with a largely featherless skin covering and larger species to endure with dense feathers in its body, as the differences to thermoregulation in response to size differences wouldn't be as obvious. That can be exemplified by some fossil formations where small scaly dinosaurs coexist with equally small feathered dinosaurs, like Psittacosaurus which lived alongside several feathered theropods, and even large feathered dinosaurs, like Yutyrannus, implying size and the distribution of filamentous integument aren't entirely dependent on each other. In the case of Triassic ornithodirans, like Coelophysis, the presence or lack of filamentous integument may be complicated to ascertain at the end of the day. Ideally, however, given it is usually accepted that dense filamentous covering is a basal trait in dinosaurs (given basal ornithischians and small theropods are known to have had it), it's fair to assume Coelophysis probably was covered in feathers, purely due to phylogenetic relationships.
  • The hands of the Coelophysis should not be pronated.
  • Coelophysis is known to have been sexually dimorphic, with two distinct body morphs, a gracile morph that likely represents females and a more robust morph that likely represents males, being known from the vast amount of specimens of the animal. However, all the Coelophysis individuals in the episode are depicted with identical body proportions.
  • Coelophysis didn't evolve until 4 million years after the episode's setting.
  • Dinosaurs probably evolved 23 million years before the setting instead of 10, as proven by the recently discovered Nyasasaurus, said to be 243 million years old. However, whether it is classified as a true dinosaur or a close relative is still debated.
  • Placerias may not have been as common as depicted in the program, as Placerias remains are generally concentrated in a single area of the Chinle Formation, the Placerias Quarry, with finds of the animal outside the quarry being much rarer. The show does state that Placerias are supposed to be rare, despite the numbers shown in the program.
  • Placerias may have had some hair coverage on their bodies, though this is still debated. No definite proof exists of the existence of hair-like filaments in non-cynodont synapsids, but it is certainly possible dicynodonts could have had them. If so, it doesn't seem likely that the skin would be covered in a dense pelt of hair, and more recent evidence seems to support a more naked hairless skin for the group.
  • It is stated in the program that Placerias is "the last of its kind" and "an endangered species." However, dicynodonts actually persisted after the extinction of Placerias, with species such as Lisowicia being known from later Triassic rocks than Placerias. It was however the last dicynodont known from North America.
  • Placerias is called a reptile in the program, when it was actually a synapsid.
  • Archosaurs generally don't mark their territories with urine, unlike the male Postosuchus in the program. It's likely that, just like their crocodilian relatives, Postosuchus didn't mark their territory at all, maintaining and defending their hunting ground from intruders. However, we do know crocodilians may excrete water from their cloaca in a similar manner to what is seen in the program. Important it is to note that the extant archosaur diversity may not be reflective of the possible variety ancient extinct archosaurs behaved, so this behaviour is not impossible.
  • Postosuchus is now known not to have walked in a quadrupedal posture. It is instead believed to be bipedal. However, this theory was still debated when the series was made.
  • Postosuchus measured 13-16 feet (4-5 meters) long, not 19 feet (6 meters) as said in the program.
  • Thrinaxodon was long extinct by the time the program takes place being from the Early Triassic rather than the Late Triassic. It also lived in South Africa and Antarctica, not North America. However, an unnamed species of cynodont is known only from teeth in the Chinle Formation, so the reconstruction of this cynodont was therefore based primarily on Thrinaxodon. Other cynodonts, like Arctotraversodon and Boreogomphodon lived 220,000,000 BCE in what is now North America, but these species were most likely all leaning to herbivory, and don't match the morphology of the cynodont seen in the episode. An undescribed species of dromatheriid is known from that time in North America as well. A more accurate replacement could be the recently described Kataigidodon. Even though it wasn’t described until November 2020, it lived in the same time and place as the episode was set in, marking this creature the first undisputed described cynodont from the Chinle Formation.
  • Plateosaurus couldn't move in a quadrupedal stance, and was an obligate biped. However, this discovery was made after the release of this episode.
  • Plateosaurus lived in Europe , but not in North America, where the episode takes place, and despite the continents all being connected, it most likely wouldn't have traveled such long distances. Recent studies on thermoregulation of Triassic ornithodirans support the presence of large sauropodomorphs, like Plateosaurus, in less hotter regions, which explains why Triassic sauropodomorphs are largely absent from regions around the same latitude as the Chinle Formation. However, sauropodomorph footprints are known from the Chinle Formation.
  • Plateosaurus didn't evolve until 6 million years after the episode's setting.
  • Peteinosaurus lived in Europe, not North America, and despite the continents all being connected and the episode stating that it is "an exotic hunter from far and wide," there isn't any real indication that it traveled such long distances. Some species of Triassic pterosaurs did exist in North America, but they were part of the Dimorphodontidae family, such as Caelestiventus, or the Eudimorphodontidae family, like Arcticodactylus, and lived 208-201 million years ago, after the setting of the episode.
  • The head of the Peteinosaurus is a little bit smaller than it would have been in life.
  • Although pycnofibres are present on the Peteinosaurus animatronic, they would very likely be much denser on the real animal.
  • When the Peteinosaurus is shown on the ground, its wings are seen to fold in from the sides. However, in the real animal, the wings would have folded in from the back, with the metacarpals rotating and causing the front digits to point backward. The tips of the wings are also too pointed, with the real animal likely having round wingtips in life.

Time of the Titans

  • Diplodocus held its neck in a slightly higher position than shown in the series.
  • Diplodocus was probably not the longest of all sauropods as stated. There were other sauropods longer than Diplodocus, such as Supersaurus.
  • There is no evidence for an ovipositor in Diplodocus. It was pure speculation by the creators of the series, who based it off of turtles. It is most likely that large sauropods preferred to lay their eggs while laying on the ground, with their cloaca close to the ground of the nest. The ovipositor hypothesis was an attempt at trying to go around the believed problem of having sauropods squatting to lay their eggs, but in reality, sauropods, even the largest ones, could lay down on the ground just fine.
  • There is slight shrink wrapping on the heads of Diplodocus, Allosaurus, Stegosaurus, Brachiosaurus, and Ornitholestes. In reality, the skull openings would likely not be externally visible.
  • Sauropods like Diplodocus are believed to have had more soft tissue around their necks.
  • The nostrils of the Diplodocus and Brachiosaurus are located towards the back of the skull. However, it is now believed that the animals' nostrils were actually located much farther forwards on the skull.
  • The feet of the Diplodocus and Brachiosaurus are more elephant-like, whereas the feet of the real animals had metacarpals that were positioned like pillars in a semicircle, creating a hollow back of the hand that was ideal for supporting the animals' large mass.
  • The large claw on the front feet of Diplodocus is missing from the model, as are the three large claws on the hind feet.
  • Ornitholestes didn't have a nasal crest. It was thought to have during the production of the show, however, due to the holotype specimen having a broken nose.
  • Ornitholestes was likely covered in feathers, based on its phylogenetic position, which did appear in the companion book. However, the show itself does show some primitive feathers displayed in some portions of the body, in the form of quills.
  • The head of the Ornitholestes model is slightly too large compared to the rest of the body.
  • The lower jaw of Ornitholestes slightly turns down, which is not seen on the skull of the model from the show.
  • Ornitholestes is now thought to have had sickle claws and retractable second toes like those of dromaeosaurids due to its recent classification as a maniraptoromorph. This would make it an early maniraptoran.
  • Ornitholestes and Allosaurus could not pronate their hands.
  • Anurognathus were micro nightjar-like insectivores, and there isn't any indication that they behaved like modern oxpeckers. Its anatomy in the show is also very inconsistent with the real animal, with a typically elongated neck, deep skull, small wings that fold in from the sides, too pointed wingtips, and a too-thin coat of pycnofibres.
  • Anurognathus didn't live in North America, only in Germany, although there are other pterosaurs from the Morrison Formation, such as Mesadactylus and Kepodactylus. This error was fixed in The Complete Guide To Prehistoric Life.
  • The head design of the Allosaurus is inaccurate; the crests are placed right above the eyes, when they were actually further down the skull, the small ridges in front of the crests are completely missing, and the snout turns down at the end, whereas the snout remains straight at the end in the real animal. Although this is still debated, it is also likely that, like many non-avian theropods, Allosaurus would have had immobile, lizard-like lips that would have covered its teeth when its mouth was closed. These errors were mostly corrected in The Ballad of Big Al, although the lip issue still remains.
  • Allosaurus may have been solitary hunters as opposed to the hunting pairs seen in the episode. It is possible hunting mobs would have happened, with no hierarchy whatsoever, but once they gathered to feed together, there could have been heavy competition. But it is also possible that they hunted in pairs.
  • Allosaurus is said to be the top predator of its age. In reality, the top predator of the Late Jurassic Morrison Formation was the much larger Torvosaurus, a genus of megalosaurid dinosaur.
  • Allosaurus is now thought to have delivered a muscle-driven bite to prey animals. In the episode, however, the Allosaurus is shown killing a baby Diplodocus by biting its neck like a Tyrannosaurus rex.
  • The Brachiosaurus model is based on Giraffatitan, which has been classified as a African species of Brachiosaurus at some point in time, due to it being much more complete. Because of this, the Brachiosaurus model is slightly inaccurate. In reality, Brachiosaurus would have had a longer and deeper torso, a longer and taller tail, and would have carried more of its mass on its forelimbs.
  • Brachiosaurus weighed between 28 and 58 tons, not 70 tons as mentioned in the program.
  • The raised bump on the head of the Brachiosaurus model is somewhat thin. In reality, the bump would possibly have more soft tissue around it.
  • Brachiosaurus is stated to be "the largest land animals that have ever existed," and it is later suggested that "life would never again be this large." However, several somphospondylan species, Apatosaurus, Barosaurus, Mamenchisaurus and Maraapunisaurus reached even larger dimensions than those of Brachiosaurus. And contrary to what was stated at the end of the episode, sauropods persisted into the Cretaceous period, but flourished in the southern continents, with only a few sauropod genera in North America that lived millions of years after the Late Jurassic period, which is the time period that the episode is set in.
  • Stegosaurus could not change the colors of its plates by flushing blood into them, as preserved integument impressions of Hesperosaurus have shown stegosaur plates were covered in a horny sheath, not skin.
  • The scales of Stegosaurus were polygonal in shape with large oval tubercles interrupting them. These tubercles are not present on the skin of the model in the program.
  • Stegosaurus is depicted as only having four digits on its front feet. However, the real animal actually had five digits on its front feet.
  • The plates of the Stegosaurus in the episode are far larger than those of any known specimen of the animal.
  • Since the discovery of Sophie, a relatively complete Stegosaurus, it is now known that Stegosaurus had a slightly longer neck and tail with more downturned spikes and a shorter torso and back legs, reducing the curve in the animal's back.
  • The environment of the episode is depicted as forested with some plains, while the actual environment of the Morrison Formation was far arider. However, this does not mean that the type of environment depicted in the episode did not exist in the formation, as the formation was very intercut between arid areas and regions with lush vegetation. Also, this was mostly corrected in The Ballad of Big Al, which has shown the Morrison fauna existing in a more arid environment.

Cruel Sea

  • The episode is set in the Oxford Clay, a formation which dates from the Callovian to the Oxfordian 166-157 million years ago, not in the Tithonian 149 million years ago. Therefore, a large portion of the cast, with Rhamphorhynchus being an exception, are misplaced in time.
  • The narration in the episode states that Ophthalmosaurus possessed "long, toothless snouts." However, fully grown Ophthalmosaurus specimens show that they did possess teeth. Interestingly, these teeth are present in the Ophthalmosaurus model used in the episode, meaning that this error was likely a narration mistake, which is not present in the US version.
  • There is no evidence that adult Ophthalmosaurus ate their young.
  • Liopleurodon wasn't even half as big as it was in the show. It wasn't 25 meters long and 150 tonnes, but around 6.4 meters long and 1-1.7 tons, being more than three times smaller than an orca. This gargantuan size comes from very fragmentary remains, such as the " Monster of Aramberri", which has been considered to be a 15 meter long, subadult Liopleurodon or large Sauropod vertebrae of the Oxford Clay which were once considered Pliosaur vertebrae. These ideas have been considered unlikely later which led to the downsize to 20 feet.
  • Liopleurodon lived from the Callovian to the Kimmeridgian and was extinct by the Tithonian. A possible replacement would be the larger Pliosaurus, which lived at the time.
  • There is slight shrink wrapping on the heads of the Liopleurodon and the Eustreptospondylus. In reality, the skull openings would likely not be externally visible.
  • Long-necked plesiosauroids and short-necked pliosaurs such as Cryptoclidus and Liopleurodon respectively are now thought to have flukes on their tails, not smooth lizard-like tails like in the series. However, the known specimens that possess these flukes on their tails are not assigned to either genus and this discovery came long after the series aired.
  • Cryptoclidus couldn't go on land like turtles or pinnipeds, as they were so adapted for aquatic life that it would be more of the equivalent of a whale or shark going on land: it would be beached and dead.
  • Cryptoclidus did not get as big as 8 tons. It probably only weighed around 1 ton or less.
  • Cryptoclidus lived in the Callovian and Oxfordian and was extinct by the Tithonian. A possible replacement would be Colymbosaurus or Kimmerosaurus, which lived at the time.
  • The head of the Cryptoclidus seen in the episode is slightly too large compared to the rest of its body.
  • Rhamphorhynchus lacks many skeletal features required for a skim-feeder, therefore it is believed to not have fished that way; it most likely dove underwater to hunt the fish.
  • Rhamphorhynchus had a shorter, thicker neck and longer wings that folded in from behind when walking. The tips of the wings are also too pointed, with the real animal likely having round wingtips in life.
  • Rhamphorhynchus, like all pterosaurs, is believed to have possessed skin covered in a coat of pycnofibres through most of its body, a feature not present in the reconstruction of the species seen in the episode.
  • The tail veins of the Rhamphorhynchus seen in the episode should be slightly more asymmetrical.
  • The tips of the jaws of the Rhamphorhynchus seen in the episode seem to be hard, keratinized structures, when in reality the tips were soft tissue structures.
  • Eustreptospondylus lived in the Oxfordian, not the Tithonian. A possible replacement would be the recently discovered Juratyrant, a five-meter-long relative of the Cretaceous Tyrannosaurus.
  • The skull design of the Eustreptospondylus is inaccurate; the head is far too short and wide, there are crests present above the eyes, which the real animal is believed to have lacked, and the snout is straight at the end, whereas the snout had a slight downturn in the real animal. Although this is still debated, it is also likely that, like many non-avian theropods, Eustreptospondylus would have had immobile, lizard-like lips that would have covered its teeth when its mouth was closed.
  • Eustreptospondylus could not pronate its hands.
  • The Eustreptospondylus seen in the episode are slightly too small. They are stated to be 5 meters in length, which is close to the 4.6-meter length of the holotype specimen. However, the holotype is a juvenile, meaning that it is likely that Eustreptospondylus could have reached larger sizes than depicted in the episode, with a believed adult length of 6 meters.

Giant of the Skies

  • The species of Ornithocheirus depicted in the program, O. mesembrinus, is now believed to be classified as its own genus, Tropeognathus. Though always recognized as its own species, there was a debate at the time about lumping it into the genus Ornithocheirus, the conclusion that the series went with, or splitting it into the genus Tropeognathus, which is currently believed to be the case.
  • Tropeognathus had a wingspan of only 8.2-8.7 m (27.1–28.5 ft), so it was not as large as depicted in the show.
  • There is no evidence that Tropeognathus traveled the globe, as fossils of this genus have only been discovered in Brazil. This inaccuracy was likely based on Ornithocheirus being believed to be known from both Europe and Brazil prior to the re-description of O. mesembrinus as Tropeognathus mesembrinus. As the two genera are now only known from Europe and Brazil respectively, it's unlikely that either genus engaged in lengthy, cross-continental migrations
  • Tropeognathus is depicted as showing sexual dimorphism in the program, with only males possessing crests on their beaks while females had no beak crests. Although these differences were believed to constitute different sexes when the program was released, it is now thought that these different morphs represent different genera rather than different sexes, meaning that both sexes of Tropeognathus would likely have possessed crests on their beaks.
  • When the Tropeognathus is shown on the ground, it is shown as moving in an extremely cumbersome manner. In reality, pterosaurs were likely far more agile on land than depicted in the program, with fossilized trackways of some species indicating that they were able to run on all fours. However, due to the much longer length of the forelimbs relative to the length of the hind-limbs in ornithocheirid pterosaurs like Tropeognathus, they were likely less fast-moving or agile than other pterosaurs. Some studies have suggested that ornithocheirids may have been able to move quickly for at least short periods on land by making hopping, take-off-like movements, but their primary movement speed on land was likely much slower than that of other pterosaur families.
  • When on the ground, the wings of the Tropeognathus and Tupandactylus are seen to fold in from the sides. However, in the real animal, the wings would have folded in from the back, with the metacarpals rotating and causing the front digits to point backward. The tips of the wings are also too pointed, with the real animal likely having round wingtips in life.
  • Tropeognathus is depicted as being able to feed by skimming its beak through the water in the program. Although this was believed to be accurate at the time of the program's release, as it was hypothesized that the crests on the pterosaur's beak could help the animal cut through the water more effectively, more recent research has indicated that this feeding method would not have been practical for this genus, as it is both too energetically costly for an animal weighing over one kilogram and the real animal lacked any kind of specialized beak anatomy necessary for this feeding method. In actuality, Tropeognathus likely fed by simply plunging their jaws into the water to snatch up fish.
  • Tropeognathus is stated to be unable to fly in the rain, as its pycnofibres would get too waterlogged to allow it to fly. Although this was believed to be accurate at the time of the program's release, more recent research has found evidence of pterosaurs being able to swim, such as pterosaur trace fossils left on what would have been the seafloor at the time, indicating that pterosaurs were capable of flight even if their pycnofibres became wet.
  • There is slight shrink wrapping on the heads of Tropeognathus, Utahraptor, Iguanodon, Plesiopleurodon, and possibly Dakotadon, although too few remains of Dakotadon have been found to determine if this is really the case. In reality, the skull openings likely were not externally visible.
  • The species of Tapejara depicted in the program, T. navigens, along with a second former species of Tapejara (T. imperator), is now believed to be classified as its own genus, Tupandactylus, leaving T. wellnhofferi as the sole species of the genus Tapejara currently believed to be valid.
  • Tupandactylus might have been herbivores/frugivores in a similar fashion to toucans, instead of coast-dwelling foragers as the series seems to imply (though, like toucans, it may still have had a taste for some meat).
  • Tupandactylus is depicted with ornithocheirid-like limb proportions, with massive forelimbs and short hind-limbs, offering them a cumbersome terrestrial gait. In reality, these pterosaurs, like their azhdarchid relatives, had longer hind limbs and shorter wings (albeit still obviously much larger than their hind-limbs), allowing them to be effective terrestrial foragers and potentially enabling them to run on the ground.
  • The crest of the Tupandactylus model is depicted with large ridges on its surface. These ridges are absent in preserved skulls of the two species of Tupandactylus and the single species of Tapejara.
  • The head of the Tupandactylus model is depicted as too small relative to the proportions of the rest of the body and is not as deep as it would have been in the real animal.
  • Tupandactylus is depicted as living on the coast in the program. In reality, several lines of evidence have indicated that tapejarids like Tupandactylus are more likely to have lived further inland. For instance, tapejarid fossils are usually found in geologic formations that contain either land-based or marginal marine depositional environments and carbon and oxygen isotope analyses of their bones have indicated that they may have obtained their water from freshwater regions like rivers and lakes far away from the marine environment, although the high amounts of oxygen 18 in the bones could also possibly result from consumption of seawater. Moreover, tapejarids like Tupandactylus are believed to have had a diet of fruits and seeds, which typically grow inland away from the coast, providing further evidence that these animals likely lived further inland and not in coastal regions.
  • Although sexual dimorphism could possibly have been present in tapejarids like Tupandactylus, there currently isn't any evidence of its presence in the tapejarid fossil record, suggesting that both male and female Tupandactylus may have had large crests.
  • As of 2021, Tupandactylus navigans is now thought to have a slightly different head crest, which would have been sharper and pointing forward compared to what is depicted in the show.
  • Tropeognathus and Tupandactylus, like all pterosaurs, are both believed to have possessed skin covered in a coat of pycnofibers. Although pycnofibers are present on the animatronics used in close-up shots of these genera, they are far less dense and widespread than they should be.
  • Tropeognathus and Tupandactylus both lived in the Aptian-Albian stages of the Cretaceous and thus wouldn't have evolved yet by the episode's Barremian setting. This inaccuracy is likely due to the lumping of multiple pterosaur genera leading to the misconception that genera like Ornithocheirus and Tapejara lived over a longer period of time than they really did.
  • Iguanodon is depicted as living in both North America and Europe in the program. This is due to the lumping of many iguanodontid remains into Iguanodon proper at the time, with many of these remains being split into new genera and species over the years. While the European Iguanodon depicted in the program is most likely still considered to be Iguanodon proper, although it could potentially have been based on other since-split European iguanodontids such as Mantellisaurus and Barilium, the North American Iguanodon depicted in the program is now classified as the separate genus Dakotadon.
  • Iguanodon is now known to have been far more robustly built than it appears in the program, with the forelimbs, in particular, being much more robust in real life relative to the thinner forelimbs seen in the Iguanodon model in the program.
  • When moving quadrupedally, the body of the Iguanodon model in the program appears to slope downwards. However, the real animal would have had a more horizontal body posture in life. This issue is likely also present in the Dakotadon model seen in the program, although too few remains of Dakotadon have been found to determine if this is really the case.
  • The narration in this episode states that Iguanodon was the first herbivorous dinosaur to have back teeth for grinding vegetation prior to swallowing it. While these back teeth are a feature present in Iguanodon, the genus wasn't the first herbivorous dinosaur to evolve this feature, as chewing behavior had already evolved in earlier ornithopods and was even present in the heterodontosaurids, a much older ornithischian group unrelated to Iguanodon.
  • Polacanthus is depicted as living in both North America and Europe in the program. This is due to the lumping of the North American nodosaurid genus Hoplitosaurus into Polacanthus at the time the program aired. However, since the airing of the program, Hoplitosaurus has been determined to be a separate genus from Polacanthus, with many of the similarities between the two genera used to justify their synonymy being found to actually be present in many ankylosaur genera, suggesting that Polacanthus was a genus solely confined to Europe. This error was corrected in the US version, where the American animal is identified as Gastonia.
  • The head of the Polacanthus model seen in the program is relatively elongated and lacks a beak. While the skull of the real Polacanthus is poorly known, inferences made from that of its close relative Gastonia indicate that the real animal would have had a shorter, more triangular head in life and would have possessed a beak-like many other ornithischian dinosaurs.
  • The back of the Polacanthus model depicted in the program is likely far more arched than it would have been in life, with the real animal having a flatter, more horizontally-positioned back.
  • The legs of the Polacanthus model depicted in the program are likely too long relative to the rest of the body.
  • Utahraptor isn't known from Europe, only North America. The inaccurate placement of this dinosaur in Europe is most likely due to the, now believed to be inaccurate, idea that Iguanodon and Polacanthus lived in both North America and Europe, leading to the producers hypothesizing that Utahraptor may have lived on both continents as well. Although other dromaeosaurs are known to have lived in Early Cretaceous Europe, like Nuthetes and Dromaeosauroides. These genera lived in the Berriasian stage, not the Barremian stage depicted in the program. Another dromaeosaur, Ornithodesmus, did exist in Europe during the Barremian, but it was too small to replace the Utahraptor in the program. Undescribed remains of large European dromaeosaurids from the Barremian are known, however, suggesting that a large dromaeosaur may have indeed lived in Europe during the time the program takes place, possibly the recently-described Vectiraptor.
  • Utahraptor measured 20-23 feet (6-7 meters) in length at full size, not 16 feet (5 meters) as said in the program.
  • Utahraptor is now known to have been far more robustly built than its portrayal in the program, with a short torso, large neural spines to anchor large back muscles and a short but more maneuverable tail. The head of the Utahraptor model seen in the program is also smaller and less robust than it would have been in the real animal and lacks the more forward-angled teeth at the front of the lower jaw that were present in the real animal.
  • Utahraptor more than likely had feathers running from head, to toe, to tail; the tip of the snout was likely naked, however. It even had feathers on its arms, forming wings and a feathered tail fan. Additionally, it was impossible for the hands to be pronated without being broken, with the hands being held with palms facing inwards instead of in the real animal. The hands of the model are occasionally seen to be facing palm-inward in some shots, but they are still rotated slightly too far back relative to the real animal. These errors are prominent in all dromaeosaurs in the Walking with... Series.
  • Utahraptor lived 139-134.6 million years ago and would've been extinct by 127 million years ago.
  • Utahraptor is depicted as hunting in a coordinated pack in the program. While it is still possible that they may have done so, coordinated pack hunting at the level depicted in the program is a more mammalian behavior not seen in most of the modern descendants of dinosaurs (birds and crocodiles), making it unlikely to have been present in the behavior of the real animal. However, it is possible that dromaeosaurs may have temporarily hunted in groups to bring down large prey while remaining mostly solitary otherwise, similar to modern Komodo dragons.
  • In shots featuring the animatronic Utahraptor in the program, the tongue of the animal is seen to be somewhat mobile. However, the more crocodilian-like hyoid bone, which serves as a support for the tongue seen in theropods like Utahraptor relative to the more complex hyoid bone seen in mammals and some ornithischian dinosaurs indicates that the tongue of the real animal would have been largely immobile in life. However, it is possible that dromaeosaurs like Utahraptor may have had somewhat more mobile tongues than other non-avian theropods, as some modern birds, their avian descendants, are able to move their tongues in a complex manner. However, more study is needed to determine if this increase in tongue mobility started in dromaeosaurs or if it only occurred later on in avian evolution.
  • The Iberomesornis model in the program is depicted with some traits more coherent with modern birds rather than more primitive paravians like the real animal, such as bare and scaly legs and feet instead of owl-like feathered legs and feet and a tail-fan made up of rectrices rather than just having two elongated rectrices extending from the tail or a short tuft of feathers around the tail. However, more recent research has indicated that some enantiornithines may have had more complex tail-feathering, including tail-fans, than previously realized, with this research suggesting that retrical tail-fans may have been the ancestral condition of enantiornithines. This indicates that the tail-fan of the Iberomesornis model in the program may not be an inaccuracy, although it has yet to be determined if a tail-fan or a similar complex tail-feather structure was actually present in Iberomesornis itself, as no feather impressions of the genus have been found as of yet; [enantiornithine tail fans do not have musculature associated with them, so it would not have been able to flicker its tail feathers like a modern bird]. Moreover, additional research has also revealed that some enantiornithines appear to have possessed at least somewhat bare and scaly legs and feet, although it is yet again unclear if this also applies to Iberomesornis itself, again due to a lack of feather impressions for this genus.
  • Iberomesornis lived in the Aptian stage of the Cretaceous and thus wouldn't have evolved yet by the episode's Barremian setting.
  • Iberomesornis is depicted as nesting in trees; [are notorious for being superprecocial, like modern day megapodes, and evidence from forms like Gobipteryx and Neuquenornis show that they buried their eggs in the ground.]
  • Plesiopleurodon lived in the lower Cenomanian stage of the Cretaceous and thus wouldn't have evolved yet by the episode's Barremian setting. In the US version, it is identified as Liopleurodon, creating an even bigger mistake.
  • Short-necked pliosaurs such as Plesiopleurodon are now thought to have flukes on their tails, not smooth lizard-like tails like in the series. However, the known specimens that possess these flukes on their tails are not assigned to Plesiopleurodon and this discovery came long after the series aired.
  • As the Plesiopleurodon model used in the program is a reuse of the Liopleurodon model from Cruel Sea, it is likely far larger than the real animal would have been in life. However, as Plesiopleurodon is currently only known from a single skull and a few cervical vertebrae, it is unclear as to how large the real animal may have grown in life.
  • The unidentified pterosaur seen in this episode is depicted with several inaccuracies common to pterosaurs in the series, such as lacking fur-like pycnofibers and having far too pointed wingtips. However, due to its unidentified nature, it is unclear if any other inaccuracies are present in the model relative to a particular real animal.
  • The narration for this episode states that the first simple flowers began to appear in the Early Cretaceous period. While evidence from the fossil record does indeed indicate that flowering plants began to diversify in the Early Cretaceous period, including during the Barremian stage setting of the episode, molecular dating analyses have suggested that the original diversification of flowering plants may have occurred much earlier in either the Triassic or Early Jurassic periods. Moreover, the Chinese plant genus Nanjinganthus, which has been dated to the Early Jurassic, possesses some angiosperm-like characteristics and features, leading some researchers to suggest that it represents the earliest known flowering plant, potentially pushing back the origin of flowering plants by 50 million years. However, this assertion has been disputed, with other researchers arguing that the flowering plant features observed in Nanjinganthus are actually misinterpreted fragmented conifer cones. Therefore, while the oldest undisputed flowering plants did indeed first appear in the Early Cretaceous period like the episode states, more research is still needed to determine whether or not this was their true origin point.

Spirits of the Ice Forest

  • Despite the claim that it takes place in Antarctica, the episode appears to take place in the Australian-Antarctic rift valley, as clarified by the companion book.
  • Leaellynasaura may have had feathers to keep itself warm. However, that is just speculation. Recent studies regarding the thermoregulatory abilities of dinosaurs, and also taking into reference the existence of dinosaurs without a dense feathery integument that are known to have inhabited cold climates, indicates that the presence of feathers may not be necessarily required for survival in colder latitudes.
  • Leaellynasaura lived 118-110 million years ago and would've been extinct by 106 million years ago.
  • Muttaburrasaurus is portrayed as slightly too robust, and should be wholly bipedal rather than partially. However, the latter was still debated at the time.
  • There is no evidence Muttaburrasaurus were migratory, as fossils have only been found in New South Wales and Queensland, with no evidence of their presence in Antarctica or even southern Australia. However, this is not an implausible piece of speculation.
  • Muttaburrasaurus did not have thumb spikes.
  • The ankle bone thought to belong to an allosauroid during production, on which the Polar Allosaur is based on, is now believed to belong to a group of theropods known as the megaraptorans, whose classification is disputed.
  • The "allosaur" ankle bone came from a fossil bed that dates to the early Albian, not the late Albian, where the episode is said to be set. Rapator lived in the late Albian, but lived in New South Wales, not Victoria.
  • Steropodon is live-acted by a modern coatimundi, when in reality, it was a monotreme with a gait more akin to the modern platypus.
  • Steropodon lived in New South Wales, not Victoria. A good replacement would be Kryoryctes.
  • Koolasuchus lived in the Aptian and was extinct by the Albian. Its disappearance is theorized to have been because the temperature warmed up enough for their habitats to have been compromised. It is also theorized that crocodylomorphs colonizing the area and outcompeting them may have been at play, as said in the program, however there is no conclusive evidence to say that was definitely the case. The fact temnospondyls and crocodylomorphs have been known to have coexisted at earlier times during the Mesozoic, suggests Koolasuchus probably did not disappear as a result of their arrival. However climatic partitioning between the two groups probably did allow Koolasuchus to persist as long as it did in its isolated environment.
  • The narrator says that the tuatara evolved in the Triassic and lived with the dinosaurs. In real life, it actually first appeared in the Miocene, long after the dinosaurs went extinct. However, there were other sphenodonts that lived in the Cretaceous, though fossils have yet to be found in Antarctica.
  • At the end of the episode, it states that the climate in the South Pole gets colder, causing the extinction of the animals that lived there. However, this is actually the opposite of true; the South Pole actually got progressively warmer through the rest of the Cretaceous, up until it begins to freeze after the Eocene

Death of a Dynasty

  • Montana and its life was actually still thriving before the asteroid collision, with many lush swamps and forests.
  • Tyrannosaurus could not pronate its hands.
  • The Tyrannosaurus model's rear teeth and tail are a little shorter than they would've been in life. The head is also just very slightly too blocky. The legs are too long and misshapen and the neck muscles should reach over the back of the head.
  • Tyrannosaurus is said to be 5 tonnes, but 8-10 tonne measurements are not uncommon.
  • Tyrannosaurus could have had some form of feathers. However, this enters into conflict on what is believed to have been the integument of tyrannosaurids. Based on fossil evidence, it is believed tyrannosaurids were covered in scaly skin through most of the body, and there would be little space for relevant feather coverings, though small and/or sparse feathering could be present in some portions of the body.
  • Tyrannosaurus most likely used low-frequency sounds rather than the full-throated roaring in the show. It may have also communicated with its mouth closed, as recent evidence suggests. However, this was not known at the time of production.
  • Dromaeosaurus has the same inaccuracies as the Utahraptor as well as two additional ones: the skull shape is too blocky and stout, and it lived in the Campanian, not the Maastrichtian. There were two different dromaeosaurids, Acheroraptor and Dakotaraptor, which lived in the episode's setting, but had yet to be described during the production of the program.
  • Dinilysia was already extinct by the Maastrichtian, having lived 85 million years ago. It also only lived in South America, while the episode takes place in North America. A good replacement would possibly be Cerberophis, which lived in North America.
  • "Anatotitan" is no longer its own genus and is now a species of Edmontosaurus, Edmontosaurus annectens.
  • E. annectens, like all hadrosaurs, didn't have thumb spikes like their iguanodontid cousins.
  • Torosaurus is shown and said to be very common in Montana, right before the asteroid impact. It is implied this episode is set in what is today the Hell Creek Formation. However, according to stratigraphic data, Torosaurus wouldn't have been around in the upper Hell Creek Cretaceous strata, in contrast to the other much more common ceratopsid of that region and time: Triceratops prorsus. Given that the very presence of Torosaurus is inaccurate. It is not completely impossible for Torosaurus to have existed around this area at this time, but that would be speculation that contradicts the known stratigraphic data.
  • Deinosuchus was extinct by this time, also being from the Campanian rather than the Maastrichtian. There were crocodilians during this time and period, Borealosuchus and Brachychampsa, but both were too small to fill the role of the large crocodilian shown in the episode. The crocodylomorph was more likely a Thoracosaurus, which is believed to have reached large lengths of up to 8 meters.
  • Deinosuchus is described as being a "1-tonne crocodile". In reality, Deinosuchus weighed nearly 9 tonnes and was an alligatoroid, not a crocodile.
  • Deinosuchus's jaws like modern alligators, were also wider in real life than the gavialine jaws of the one depicted in the episode.
  • We now know that the eyes of smaller neornithischians are more pronounced than depicted in the episode, resembling how the eyes look in eagles, with "eyebrows".
  • Due to being a re-skin of the Ornithocheirus model with only the beak crests removed, Quetzalcoatlus only shares a faint resemblance to what we now know it looked like. The program's design has a much bigger head than the real animal and a large flat crest instead of a tiny notch at the back of the head. The real animal's neck is much, much, longer than the program's design. The final result ends up looking more like another pterosaur, Ludodactylus. The design of the animal would be just a bit more accurate if it was a nyctosaurid or a pteranodontid (despite the size not really matching).
  • As of now, the presence of Quetzalcoatlus at Hell Creek is debated, though there are remains of indeterminate azhdarchids that could be from Quetzalcoatlus.
  • Didelphodon was not badger-like. In reality, it had a head like a Tasmanian Devil and a body like an otter. This was due to the animal only being known from teeth at the time of the program's production.
  • Didelphodon was a durophagist, and is placed among semi-aquatic species in studies regarding Mesozoic mammal locomotor abilities. This is rather distinct from the animals scurrying about furiously for terrestrial prey in the program.
  • Ankylosaurus was not as tall and bulky in reality as it appeared in the series.
  • In the US version, the ornithopods are identified as Hypsilophodon, which was actually lived in the Early Cretaceous. It also lived in England, not North America.

The Ballad of Big Al

  • Big Al is a member of the recently described species Allosaurus jimmadseni, which lived in the Kimmeridgian, not the Tithonian.
  • Big Al is depicted as being 9 meters long, however, further examination of his fossils has shown he was actually 7.5 meters long when he died.
  • Othnielia should now be known as Nanosaurus, as more complete remains of Nanosaurus have since been found that show that Othnielia is its junior synonym.
  • Same issues with Ornitholestes, Diplodocus, Brachiosaurus, Stegosaurus and Anurognathus as seen above.
  • No definitive Allosaurus specimen has been found to be longer than 10 metres like the female shown in the film, when the other allosaurs eat the sick Diplodocus. However, there are some fragmentary remains suggesting they could have grown up to 12 metres which is slightly smaller than how the female Allosaurus is depicted as, additionally, most Allosaurus fossil specimens haven't reached skeletal maturity yet, and therefore they probably had the potential of growing to 10-13 meters in length in the oldest specimens. The so-called Saurophaganax would serve as a potential more accurate replacement, but despite the remains suggesting that Saurophaganax might have been bigger than Allosaurus, many scientists suggest instead that Saurophaganax is just a more mature Allosaurus or a different species of Allosaurus altogether. It grew bigger than 10 metres, it was closely related and it did live in the same place the show was set in, but it died out 5 million years before the time the episode was set in.

Walking with Beasts

New Dawn

  • The notion that mammals from the Paleocene and the early Eocene were all tiny creatures living under the oppressive domain of giant birds and other surviving archosaurs, such as the land-dwelling crocodylomorph Boverisuchus, is incorrect. We know that the first mammalian megafauna appeared a few million years after the K-Pg extinction, starting with pantodonts like Pantolambda and Bemalambda, as well as mesonychids (carnivorous ungulates) like Dissacus, all of these emerging during the early Paleocene (66-60 mya). Although birds, crocodylomorphs, turtles, and squamates were also diversifying and taking a very important part in the ecosystem, even as megafaunal creatures, the mammals took up the role of dominant land vertebrates much faster than them, and by the time of the show (49my) mammals were already dominating the landscape, by comparison. This however does specifically apply to Europe, where Gastornis and ratites are the largest land animals for most of the Eocene, a situation compared to Pleistocene Madagascar and its elephant birds.
  • Gastornis was an herbivore, in reality, lacking the hooked beak and strong, sharp talons that are characteristics of a predatory lifestyle, and calcium isotopes in the bones of specimens revealed that its dietary habits were similar to those of both herbivorous dinosaurs and mammals.
  • Eurotamandua is depicted as an actual tamandua, when it was a rather bizarre mammal of possible pholidotan affinities.
  • Ambulocetus was depicted as living in Germany, when in reality it was only found in Pakistan. However, the episode does say that it might have migrated from its original home.
  • Ambulocetus had straight limbs, unlike the sprawled legs of the one in the program.
  • Ambulocetus is depicted as amphibious. However, recent research suggests that it was probably fully aquatic. However, it is likely that it would still go to land to give birth to their young. Either way, if moving on land, they would likely have moved in a clumsy fashion, like seals.
  • The primate Godinotia was a strepsirrhine, like a lemur, and would probably have resembled a modern lemur in life (as they are the most basal of primates) in contrast to the monkey-like reconstruction seen in the show.

Whale Killer

  • Basilosaurus swam in a serpentine way and had weak muscles so it couldn't swim fast for long.
  • Andrewsarchus is depicted just like a mesonychid, when it was a more entelodont-like artiodactyl in real life. However, this is a very common and big mistake as most drawings/paintings of Andrewsarchus depict it like a mesonychid. Only a few correct drawings exist. Pachyaena was a very large mesonychid that inhabited the Eocene period in Asia, however, it lived in the Early Eocene, not in the Late Eocene like in the show (the same goes to Andrewsarchus which went extinct in the Middle Eocene). Mongolonyx was also a large mesonychid, this one lived in the Late Eocene, however it was in Mongolia, not in Pakistan, like in the show. In any case, we can agree that mesonychids were around in Asia, at the time, and probably were significant land predators in those regions.
  • Embolotherium possibly had a large, bulbous nose instead of the crest seen in the program, this is thought because of the nostril openings extending to the top of the crest, however, there is no evidence of this.
  • Dorudon was most likely not a social animal. However, the gatherings seen in the show might be exclusive to the breeding sanctuaries, where, outside of that circumstance, Dorudon retains a non-social lifestyle.

Land of Giants

  • Indricotherium should now be known as a synonym to Paraceratherium since the name Paraceratherium was the first name given to the animal. However, the show does refers to the animals as indricotheres, not specifically stating the name Indricotherium, which, in that case, would be correct.
  • Hyaenodon is said to have bone-crushing jaws. In real life, they were for shearing rather than crushing. It's still likely that they were capable of crushing some bone, though.
  • Hyaenodon had a slightly longer muzzle than is shown in the series.
  • Cynodictis is depicted walking on its toes, similar to wolves and dogs. In reality, Cynodictis walked on its feet, similar to bears and humans.
  • Cynodictis lived during the Late Eocene and Early Oligocene and died out by the time the episode takes place in. However, other species of bear dogs probably did exist during the same time and place.

Next of Kin

  • It may feel unlikely that Australopithecus afarensis could scare off large chalicotheres, unless these were quite skittish in nature (something that hardly can be determined with mere fossils).
  • Dinofelis was actually more adapted to hunt animals on the ground and in the prairies, however, in the show, they are shown hunting early hominids. Although not impossible, there were other felids likely more adapted to hunting hominids and their more forest-dwelling kin, such as pantherines.
  • The trunk of the Deinotherium is depicted as being rather short, when compared to modern elephants. Although that is suggestive that they had trouble in feeding or drinking, some interpretations favor the short-trunked interpretation, mostly due to the fact that Deinotherium diverged from modern elephants pretty early in proboscidean evolution, so structurally their trunks were possibly rather primitive and more tapir-like rather than elephant-like. The muscle attachment sites on the skull are also coherent with a more developed area around the mouth area, rather than around the nasal area, and that is suggestive of a rather more tapir-like trunk. In this interpretation, the action of eating and drinking would likely be achieved without the strong aid of the trunk, maybe developing a stance like giraffes during drinking or even entering the water sources entirely to drink, as a few animals do, including even modern elephants in the occasion.


  • Smilodon living in social groups is a controversial theory at best, but all experts agree that the lion pride idea is extremely unlikely, since male and female Smilodon are not known to have had sexual dimorphism, in sharp contrast to lions, where the two sexes are very differently built and also because both sexes appear to have been active hunters. It is possible that their social structure was more like that of modern-day wolves, with males and females providing a similar role in the pack order, if they were indeed social.
  • This episode relies on the now outdated hypothesis that North American carnivores like Smilodon outcompeted native South American carnivores like terror birds, sparassodonts and Macroeuphractus. In reality all of these became extinct over one million years before carnivorans (barring procyonids, which were already present in the Miocene as bear-like omnivores) arrived, and Titanis at least co-existed with North American carnivores for two million years.
  • Macrauchenia probably had a shorter trunk than what is shown in the film. It would most likely either have had a trunk like those of Saiga antelope or not have had a trunk at all, but rather a moose-like snout.
  • Smilodon was a bulky predator that was built to ambush and wrestle its prey to the ground, and was ill-equipped for high-speed chases and quick, sharp turns like modern big cats, so the Macrauchenia chase scene is inaccurate.
  • Phorusrhacos probably did not have wing claws, just like the seriema, its closest living relative.
  • Phorusrhacos was probably stockier and had a shorter neck than is shown in the series, and the most currently accepted estimates give it a height of just 1.6 meters tall.
  • Phorusrhacos lived in the Miocene, from 20,000,000 BCE to 13,000,000 BCE, not the Pleistocene a mere 1,000,000 BCE. Psilopterus material has been attributed to the Pleistocene, but the validity of this dating is dubious and hard to ascertain. Psilopterus was also too small to be a feasible replacement to the Phorusrhacos in the episode. Titanis was also attributed to Pleistocene strata and was big enough to fit a similar role to the terror birds from the episode, however the exact dating of the known material is inconclusive on whether or not it would have been found in the Pleistocene, and if so, would probably only live in the earliest stages of the epoch. Titanis would have also lived in North America, instead of South America.
  • There is no evidence that Megatherium ate carrion to supplement its diet, but it is far from impossible as some herbivores today have been recorded eating meat, and some paleontologists do believe Megatherium was partly carnivorous, though that carnivory claim has little fundament to it, given carbon isotope analysis strongly suggest Megatherium was a obligate herbivore. [1]That said, its not impossible meat-eating was a very occasional behaviour, to gain extra nutrients in their diet, as observed in other herbivores, including in modern day sloths. To corroborate this idea, a study from 2021 has found evidence for omnivory in Mylodon, another type of ground sloth, so it's possible that Megatherium ate meat on occasion too.

Mammoth Journey

  • Male Woolly Mammoth skulls did not have tusks that curve over another. Only Columbian Mammoths are known to have this feature. However, this feature may have been exceptionally possible in some individuals.
  • The Neanderthal may not have been the last survivor of the genus Homo, besides humans: the denisovans, may have went extinct around the same time as Neanderthals or long after.
  • The Cave Lion's model is reused from the Smilodon's, minus the sabres. Cave paintings reveal that it actually had much longer, tufted tails, a primitive to nonexistent mane, and bright yellow fur instead of white. It would've been a larger and whiter version of the modern lion.
  • The Neanderthal species had died out 40,000 years ago, 10,000 years before the time that the episode takes place.

Walking with Cavemen

  • Lucy was not killed by being hit with a stick. It's been determined that she probably died from falling out of a tree. However, the reasons for the fall may still be uncertain.
  • During a brief moment when going underwater, a Basilosaurus can be seen. However, it says that this is happening during 8,000,000 BCE, and Basilosaurus lived until 36,000,000 BCE. However, it is possible that this creature was supposed to represent other extinct whales.
  • Homo naledi has been believed to have been a possible ancestor of our species instead of Homo habilis, when it was initially described. However H. naledi was described in 2015, more than a decade after Walking with Cavemen aired, so they could not have known about this species. However, this conclusion has since been proven unlikely, because it was since determined that Homo naledi lived from 335 to 236 thousand years B.C., which means they were too young to be our ancestors. Homo habilis is more primitive and probably evolved to Homo sapiens and Homo naledi separately.
  • Some paleoanthropologists do not recognize Homo ergaster and Homo erectus as separate species. Even if they were separate, some believe H. erectus did survive and evolved into the highly controversial H. floresiensis. Anyway, Homo ergaster is still a valid species, as well as Homo erectus and it is required a further research to reach to a conclusion to this systematic problem. The consensus does support Homo ergaster and Homo erectus as different species, with Homo floresiensis possibly being a much earlier offshoot.
  • Some paleoanthropologists believe the African Homo heidelbergensis is merely an archaic form of modern humans. However, this is debated, and may not be true, as phylogenetic evidence seems to support a more neanderthal affinity to the Heidelberg men.

Walking with Monsters

Water Dwellers

  • The species of long-tailed Anomalocaris from Cambrian Stage 3 Chengjiang, didn't reach 2 metres long, only being 7 centimetres, although that is thought to be become larger, about 50 cm long, based on frontal appendage of Anomalocaris saron, which that specimen of Anomalocaris previously belonged. But recent analysis seems to support that it may not have been an Anomalocaris at all, but rather a relative. Also, long-tailed Anomalocaris (Anomalocaris sp. (ELRC 20001)) is no longer considered as A. saron (now called as Houcaris saron), so estimation of large size is incorrect. In fact, no species of Anomalocaris got that big. The closest was a larger species from the later Burgess Shale in British Columbia, Anomalocaris canadensis, which was about 40 cm long (including appendages about 65 cm long).
  • "Anomalocaris" saron didn't feed on trilobites, rather more soft-bodied creatures.
  • "Anomalocaris" saron wasn't the first-ever apex predator, nor was it the apex predator of its time and place. The larger Omnidens, being 1.5 metres in length, was the largest Cambrian animal known. Anomalocaris canadensis, however, was the apex predator of the later Burgess Shale from the Miaolingian, though it did not surpass Omnidens in size.
  • In the confrontation between two Anomalocaris, the loser supposedly gets wounded by having its rigid armor split. However, this was based on an old now invalid theory, and it is now known that the only relevant armor on the animal was the tripartite carapace on the head. The cuticle of Anomalocaris is sometimes believed to have been soft and flexible.
  • The Silurian segment of the episode actually doesn't take place in the Silurian. The segment's setting is 418 million years ago in the Early Devonian, while the Silurian actually lasted from 443.8–419.2 million years ago.
  • Brontoscorpio was found in England, not Wales. However, given the geographical proximity of the two places (even during the Silurian) it's still considerable that Brontoscorpio inhabited Wales.
  • Brontoscorpio may have actually molted underwater due to its size.
  • Pterygotus was not the largest arthropod of all time, nor did it reach the sizes mentioned. However, the true holder of the title, Jaekelopterus rhenaniae, could attain closer proportions. It was once regarded as possible that the two genera could be lumped, but that hypothesis was long disregarded even before the program's release.
  • According to the program, scorpions like Brontoscorpio "have no memory at all". However, this may not be true, as most animals have at least some memory.
  • Cephalaspis was not ancestral to tetrapods. At the Late Silurian, the most likely replacement would be the already fully jawed Psarolepis.
  • In the Devonian segment, angelfish can be spotted. One can be seen in the background both when the segment starts and when the Hynerpeton is chased by the Stethacanthus. However, there were no teleosts in the Paleozoic era, much less in the Devonian. However it is still possible to be a primitive actinopterin, a clade of bony fish that includes (beyond teleosts) the holostei and the chondrostei (the latter already present at the Devonian). However, the fish appearing in the shots were likely a mistake.
  • Stethacanthus was likely an ocean-going animal and it wasn't a true shark.
  • Hyneria was smaller than depicted in the episode, attaining lengths of 2.5-3.7 metres, as opposed to 5 metres.

Reptile's Beginnings

  • The Mesothelae spider in the program was based on Megarachne, which during the show's production was thought to be the largest spider ever to live. However, as production was wrapping up, another specimen of Megarachne was discovered that led to the realization that it was actually a eurypterid, leading to the animal in the program being referred to as a speculative species of giant mesothelae spider (an actual group of extant spiders that existed back in the Carboniferous, but its members only vaguely resembled the one from the program and were nowhere near as large).
  • Proterogyrinus was not an amphibian, though it may have lived an amphibious lifestyle. It was possibly a reptiliomorph.
  • There is no evidence suggesting that Arthropleura had powerful jaws, given the fact that its mouthparts have never been preserved along with the rest of the animal.
  • Arthropleura is now known to be a true millipede rather than a distant relative of them.
  • Arthropleura's ability to rear up is purely speculative, and it might not have been possible in real life.
  • Petrolacosaurus is incorrectly shown evolving into the synapsid Edaphosaurus, when in fact, it was an early diapsid, and could therefore not have been the ancestor of any synapsids. The most basal synapsid, Protoclepsydrops, would have been a more suitable candidate. However Edaphosaurus were already present 300 million years ago, so their ancestors would still be Edaphosaurus.
  • The Dimetrodon hatchlings are shown with their back sails fully erect, when they probably wouldn't have grown them yet.
  • The skin texture of Edaphosaurus and Dimetrodon may be slightly off. It is hypothesized they had scutes on their skin, similar but different to the ones on crocodilians. It's possible they lacked the scales of lepidosaurian reptiles.
  • There is no evidence that Dimetrodon were cannibals, however, this is not impossible.
  • There is no evidence that Dimetrodon eggs would take 7 months to hatch, but we do not have any information on Dimetrodon reproduction whatsoever, so any reconstruction of their reproductive habits will always be speculative until potential future discoveries prove otherwise.
  • Dimetrodon is depicted as living in a desert-like environment, when in fact, Dimetrodon is known to have lived in a swamp-like environment. However, it is still possible that some populations lived in slightly more arid environments than the average.
  • The tops of some Dimetrodon's neural spines could have been exposed bone rather than covered with a full sail, though that is debated.
  • In the programme, Dimetrodon and Edaphosaurus are described as "mammal-like reptiles". However, they were not reptiles, as synapsids form a distinct clade within Amniota, which also contains "reptiles".

Clash of Titans

  • The Gorgonops and the Rhinesuchus are only known from South Africa, yet in Clash of Titans, they are portrayed living with Scutosaurus, which was only found in Siberia. However, the gorgonopsid featured in the program was more likely an Inostrancevia, as it lived at the same time and place as Scutosaurus. Meanwhile, Rhinesuchus is also from South Africa. Although it is named, in the episode, as a labyrinthodont, a rather wide nomination that has been traditionally used to describe the more primitive amphibian or amphibian-like tetrapodomorphs that existed back then, including ichthyostegalians, temnospondyls, etc. The term labyrinthodont has since been disused, as it is ultimately nearly synonymous with the Stegocephalia clade as a whole, and conveniently removes amniotes, lissamphibians, and lepospondyls out of its definition. A more accurate replacement for it could be Konzhukovia, which lived in Russia at the same time the first part of the episode was set in and was a labyrinthodont just like Rhinesuchus.
  • It is possible that gorgonopsids had hair. However, correlations with the MSX2, a gene that is believed to be correlated with the manifestation of the parietal foramen and the distribution of hair in mammals, has been used to determine which extinct synapsids might have been covered in hair. According to studies done in regards to the manifestation of this gene, the mutations that activate the formation of parietal foramen, may be accompanied by the loss of extensive hair distribution, and that correlation has been made in extinct synapsids. Gorgonopsids, therocephalians, and non-probainognathian cynodonts (which include Thrinaxodon and cynognathians) had parietal foramen, suggesting they didn't have an extensive hairy integument.
  • Euparkeria is not an ancestor of the dinosaurs due to it being more basal than the crocodilian-dinosaur split. Probably the most likely ancestor of the dinosaurs at the time would be a basal dinosauromorph, likely quadrupedal.
  • The therocephalians featured in the episode, Euchambersia, would already be extinct 248,000,000 BCE. They lived from 256,000,000 to 252,000,000 BCE A possible replacement would be Moschorhinus, which survived into the Early Triassic.
  • Euparkeria, Euchambersia and Proterosuchus never lived in Antarctica, but instead in South Africa, which was, nevertheless, geographically close to Antarctica.
  • Proterosuchus was not the ancestor of crocodilians due to it being more basal than the crocodilian-dinosaur split.

Chased by Dinosaurs

The Giant Claw

  • The episode is set 75 MYA in the Nemegt Formation, but more recent studies favor an age of 70 MYA for the formation.
  • Velociraptor may not have lived in heavily forested areas. All of the sites where Velociraptor fossils were found suggest that the animal lived in arid environments with many sand dunes (with one specimen apparently being smothered to death by a sand dune). However, knowing that there were two distinct species of Velociraptor, and that they were formidable and adaptable predators, it's still possible that some populations hunted in forested areas, although this can't be currently confirmed.
  • Velociraptor in the show lacks feathers. All Dromaeosaurids/Raptors had pennaceous feathers running from head to tail. It even had them on its arms making them resemble wings.
  • Velociraptor's claw could not disembowel prey because the underside was round therefore the claw was used for stabbing and for immobilizing prey.
  • Despite living in Mongolia, Velociraptor did not live in the Nemegt Formation. A replacement would be another dromaeosaurid called Adasaurus which lived there and was a velociraptorine just like Velociraptor itself. There are also other indeterminate dromaeosaurid fossils found in the formation.
  • Velociraptor was actually a nocturnal animal, so it would have likely hunted at night, not at daytime as shown in the Episode.
  • Tarbosaurus's arms should be facing inwards not downwards. Its head is also slightly off.
  • Tarbosaurus was depicted as being smaller than Therizinosaurus, when in reality it was larger than it.
  • Saurolophus and hadrosaurs, in general, didn't have thumb spikes like their ancient Iguanodon relatives.
  • Therizinosaurus was depicted featherless. Therizinosaurs are known to have had feathers, though.
  • It is now known that the frill bones of Protoceratops increased in length and width during the ontogeny of the animal and that the growth of the frill was greater than than the overall growth of the animal.
  • It is believed that Protoceratops most likely used its frill for sexual and dominance signaling.
  • Mononykus should have had more feathers, when taking into account its phylogenetic position. However, the shape of the feathers depicted in the program seems unlikely, as they would likely be more hair or string-like in appearance.
  • Mononykus was too large compared to the real animal. Few alvarezsaurs reached or surpassed that size, for example, the Bonapartenykus.
  • Azhdarcho is portrayed living during the Campanian 75 million years ago in the Nemegt Formation of Mongolia, when in reality it lived in the Turonian Bissekty Formation of Uzbekistan 92 million years ago. However, the pterosaur in the episode could have actually been a yet-to-be-named azhdarchid found in the Nemegt Formation often dubbed the Mongol Giant.

Land of Giants

  • Giganotosaurus was depicted on the show as the largest carnivorous dinosaur, though current size estimates favor Spinosaurus as the largest carnivorous dinosaur. However, it is true that Giganotosaurus was one of the largest land-dwelling carnivorous dinosaurs that ever existed, as Spinosaurus was semi-aquatic. Tyrannosaurus might have been heavier than Giganotosaurus however, despite the latter winning in length.
  • When the documentary was being made, the fossils of Mapusaurus had been dug and were kept in storage. It was thought that those fossils belonged to Giganotosaurus carolinii, however, after they were studied, they were classified as Mapusaurus which could, in the future turn out to be synonymous with Giganotosaurus, though that is disputed.
  • Giganotosaurus never coexisted with Argentinosaurus. Mapusaurus coexisted with Argentinosaurus however, as Argentinosaurus was found in the Huincul Formation, while Giganotosaurus was found in the Candeleros Formation. There was a titanosaur in the Candeleros Formation called Andesaurus that would have coexisted with Giganotosaurus.
  • Nigel claims that Giganotosaurus weighed " 2 tons more than T.rex". In real life that is hard to ascertain. Giganotosaurus's weight has been estimated to have been around 8 tonnes, more or less around the same as Tyrannosaurus. The fact that the two carnivorous dinosaurs were at around the same length and that precise mass estimates are complicated to obtain in these extinct taxa, it is hard to ascertain which of the two would exactly be the biggest.
  • Argentinosaurus is said to have been the biggest dinosaur. Though that title is contested, due to the fragmentary nature of several sauropods. Maraapunisaurus might have been the biggest one.
  • Argentinosaurus's neck was probably held more vertical than horizontal.
  • Argentinosaurus's body shape is largely based on Saltasaurus, like most titanosaurs were in the past. However, newer studies show that Saltasaurus had very different proportions from most titanosaurs.
  • Pteranodon didn't live in South America. It was endemic only to North America, and it lived 86,000,000-84,500,000 BCE, not 100,000,000 BCE (anhanguerids would have been possible replacements). Ornithocheiromorphs and azhdarchoids were pretty common at the time, however.
  • Tropeognathus (called here Ornithocheirus) was found in Brazil, not Argentina. However, the likelihood that pterosaurs were migrating creatures would make sense for these animals to, hypothetically, find their way into other regions of the globe, and given the geographical distance between Brazil and Argentina, it is not too far fetched.
  • Same issues with Tropeognathus as in Giant of the Skies.
  • Pteranodon should have had pycnofibers (fuzz) on its body.
  • Male Pteranodon may have had a more vividly colored crest to attract females. The beak of Pteranodon is also known to have curved slightly upwards.
  • Sarcosuchus would never have encountered many of the animals in the episode, as it lived 133 to 112 million years ago, in comparison to the episode's setting of 100 million years ago, and lived in a different region of South America, Brazil. However, it is still possible that other crocodylomorphs existed at the time and place of the show.

Sea Monsters


  • Same issues with Velociraptor as seen above.
  • Velociraptor and Tarbosaurus were unlikely to live so close to the sea, but it is possible that the featured animals were just close relatives of these, or a determined population of the said species that lived close to the sea.
  • Same issues with the Tarbosaurus as seen above.


  • Some "Sea scorpions" could go on land only for short intervals, and eat washed-up carcasses.
  • Mild time map issues, see below.


  • Dunkleosteus is claimed to have reached lengths of 10 meters. However, the largest species, D. terrelli, reached a slightly lower length of 8,79 meters.


  • Tanystropheus was an archosauromorph, and there is no phylogenetic evidence to support it would shed their tails like lizards. However, taking into account several species of sauropsids practiced tail autotomy, and that the extant archosauromorph diversity is very limiting, in comparison to the wide variety of extinct ones, back in the Triassic, for example, it is not completely unreasonable to speculate that some primitive archosauromorphs could have practiced tail autotomy.
  • Cymbospondylus is depicted as a predator of marine reptiles. However, its teeth were small and conical, likely meaning that it ate small fish and cephalopods. A better choice be would be Thalattoarchon, an ichthyosaur that looked very similar to Cymbospondylus, but was known to have eaten other marine reptiles. However, it was only discovered after the show had aired. In any way, Thalattoarchon didn't live in the late Triassic, while Cymbospondylus did, and with the latter's huge size, it is still possible that it hunted small prey (including very small marine reptiles, like pachypleurosaurs).
  • Coelurosaurs didn’t even exist until the Mid-Jurassic and possibly as far as the Early-Jurassic not the Mid-Triassic.


  • Leedsichthys size is grossly exaggerated. In reality, it was 8–17 m rather than the 27 m in the show.
  • Leedsichthys had a smoother, more elongated head than in the show.
  • Same issues with Liopleurodon as in Cruel Sea. (see above)


  • Pteranodon were diving creatures that hunted fish similar to gannets, unlike the skim feeders they were portrayed as in the episode.
  • Same other errors with Pteranodon as in Chased by Dinosaurs
  • Tyrannosaurus did not live 75,000,000 BCE. Probably the dinosaur featured in the show was actually Daspletosaurus.
  • Mosasaurs, like Tylosaurus and Halisaurus, and plesiosaurs, like Elasmosaurus, are believed to have had more pronounced tail flukes instead of lizard-like tails.
  • Tylosaurus was 14 m long, not 17 m long.
  • A recent study on mosasaurs has concluded that they were likely mainly black or dark in color, with a more whitish underbelly, not brown like the series' depiction of the animal.
  • There is no certain evidence that mosasaurs like Tylosaurus lived in large family groups. Although, it is still possible that they gathered in large groups (not necessarily family groups), like many snakes, their closest living relatives (i.e. garter snakes).


  • Arsinoitherium probably did not have a trunk.
  • Basilosaurus ability to "sing" is quite inaccurate. It and other early whales lacked the melon organ that modern whales have that is used for this action. However, Basilosaurus possibly could still produce vocalizations, however not through the melon organ.
  • Same issues with Dorudon as in Whale Killer. (see above)
  • Basilosaurus and other early whales had slightly twisted snouts. (http://ns.umich.edu/new/releases/8513)


  • Megalodon was depicted a little bit too similar to modern-day great whites. Though scientists suggest that Megalodon did look like a stockier version of the great white. The true shape of Megalodon has been under constant debate even to this day.

Time map

  • Creatures have the same issues as described in their respective sections. (See above)
  • Time periods of planet earth go much farther back than the Ordovician, but this was probably a design choice, as Nigel didn't go any farther back than this, and the time map would be significantly longer, if so.
  • Basilosaurus should be a bit further back in the timeline.
  • The Cenozoic section should be a bit bigger.

Walking With Dinosaurs: The Arena Spectacular

  • The guide states that Liliensternus has five fingers. The model used for Liliensternus actually has only four fingers, just like its real counterpart.
  • Also in the guide, Allosaurus is once referred to as Albosaurus.

Walking with Dinosaurs: Inside Their World

  • The theropods featured in the app have pronated hands, which isn't scientifically plausible
  • Gallimimus is shown with only a few quills when it really would have been covered in feathers.
  • Psittacosaurus is depicted as a quadrupedal animal, unlike the real animal, which was bipedal.
  • Psittacosaurus, according to a study in 2016, had a series of brown colors to camouflage and had a membrane on its hind legs. However, the specimen containing the fossilized melanosomes is only assigned to an unknown species of the genus (P. sp.), meaning that it is possible that the coloration seen in the app was present in life. In addition, these discoveries were made after the app's release.
  • Some specimens of Microraptor and Archaeopteryx possess fossilized melanosomes that show that they were black or iridescent black in color. However, the specimens containing these melanosomes are only assigned to unknown species of both genera (A. sp. and M. sp.), meaning that it is possible that the coloration seen in the app was present in life.
  • Spinosaurus didn't have the jaw strength or neck muscles to lift up and throw an adult Suchomimus.
  • Spinosaurus and Suchomimus never coexisted, as they lived in different regions and at different times.
  • Spinosaurus had shorter hind legs, unlike the long-limbed one seen in the app. Its hallux should also be touching the ground, and its toes might have been webbed. However, these conclusions were made with subsequent discoveries made after the app's release.

Walking with Dinosaurs: The Movie

  • The Gorgosaurus shown in the movie should now be known as Nanuqsaurus, as analysis of the Alaskan Gorgosaurus remains suggest they belong to this new tyrannosaurid genus.
  • The Alaskan troodontid remains are no longer thought to belong to the genus Troodon.
  • The design of the horns of Pachyrhinosaurus are based on Pachyrhinosaurus lakustai, but the actual Alaskan species is Pachyrhinosaurus perotorum, while Pachyrhinosaurus lakustai was native to Canada.
  • The Edmontosaurus shown in the movie has since been often classified as Ugrunaaluk, as analysis of the Alaskan Edmontosaurus remains supported their referral to a separate genus. However, this classification is still debated, now with a considerable amount of paleontologists believing that Ugrunaaluk is indeed a synonym of Edmontosaurus, which seems to be a proper conclusion.
  • Edmontosaurus regalis had a fleshy crest, however, it may have only been present in this species as opposed to all Edmontosaurus species. For example, Edmontosaurus annectens have been found with extensive skin impressions, and none seem to support the presence of such crest.
  • Quetzalcoatlus had a bigger head and longer neck.
  • Quetzalcoatlus was not native to Alaska, only in the western United States. A possible replacement would be Cryodrakon, even if fossils were only found in Alberta, Canada.
  • Alexornis was native to Baja California, Mexico, not Alaska. However, considering that he is meant to be some spiritual narrator that also takes the form of a rook (which is also not native to Alaska), this is somewhat excusable.
  • Alexornis should have feathery owl-like feet with (possibly) Microraptor-like hind-wings, fused wing fingers (as opposed to three separated clawed fingers), and more of an actual snout with teeth that are not exposed.
  • Chirostenotes fossils were found in Canada, not Alaska. However, it isn't too unlikely that some populations made their way to Alaska.
  • When Scowler defeats Patchi and abandons him, the sun sets and rises like a normal day further south. This contradicts the previously shown polar summer and winter cycle unless Patchi was somehow trapped all winter, though he probably should've starved to death if that was the case.

Walking with Dinosaurs: Prehistoric Planet 3D

  • Same issues with Pachyrhinosaurus, Troodon, Edmontosaurus, Chirostenotes, Alexornis, and Quetzalcoatlus as seen above. However, since Alexornis is never referred by name, it is possible that it could be a different species of avialan.
  • Minus the location issue, Nanuqsaurus has the same errors as Gorgosaurus, with an additional one; it is slightly oversized. However, the holotype specimen might represent a subadult.
  • The same polar winter error from above.

Wonderbook: Walking with Dinosaurs

The Great Exodus

March of the Titans

  • Pterodaustro lived before Argentinosaurus and Mapusaurus.
  • Pterodaustro did not prey on hatching Argentinosaurus and would have been a filter feeder.
  • Only the female Pterodaustro is shown as being pink when both genders would have been pink.

Terror in the Swamp

  • A Pachyrhinosaurus skeleton is briefly seen, though this genus didn't live in the Jurassic.

Impenetrable Fortress

King of Dragons