Science Marches On / Walking with Dinosaurs
While Walking With Dinosaurs
was generally accurate for when it was made, it's over 15 years old. New evidence regarding behavior, color and other details are always emerging. So, there are inaccuracies.
Walking With Dinosaurs
- Most coelurosaurs certainly had feathers. The several dromaeosaurid species surely had them, but in the franchise they are all shown featherless: this, rather than Science Marches On, might be interpreted more as Rule of Cool, or rather, Artistic License – Paleontology, since feathered raptors would have appeared "too cute"? In Real Life dromeosaurids had WINGS just like their famous relative, the "ur-bird" 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 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 surface area to volume ratio. Some think the "spikes" on Diplodocus have the same common origin of feathers, as well as the quill of the small herbivore Psittacosaurus and even the horny bumps lined on the back of several hadrosaur mummies. See 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. The documentary also avoids showing the large pterosaurs taking off almost entirely, because at the time it was uncertain how such large flying animals could lift up from the ground. It's now known that like probably pushed off their front limbs to vault themselves into the air.
- All the non-avian theropods have pronated hands, a position that is impossible in reality.
- What was thought to be evidence for "cannibalistic Coelophysis" has been discredited. Some of the evidence was cannibalism was later seen as adult Coelophysis simply having died on top of juveniles, while the stomach contents of other adult Coelophysis was determined to be that of small crocodilians, not younger Coelophysis.
- As the now-synonymous Megapnosaurus indicates, Coelophysis was nocturnal.
- The early long-necked dinosaur Plateosaurus could not walk on four legs.
- The pillar-limbed croc-relative 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 cynodonts of the size depicted in the program in the late Triassicnote . This is an example of Science Marches On rather than Artistic License – Paleontology 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 two teeth from Chinle Formationnote . However, post-WWD study indicates 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. However, some scientists do consider the two to be the same animal (although still as a separate species, Allosaurus maximus, as opposed to the species most are familiar with, Allosaurus fragilis).
- Sorry, 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 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 (and that's not even mentioning that Anurognathus isn't even known from the same continent as Diplodocus).
- Post-WWD studies indicate that 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 less than four decades to 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 Diplodocus, Apatosaurus and Argentinosaurus, which in turn probably popularized the concept - 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.
- Footprints from a baby bipedal sauropod have been recently found: Perhaps 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 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.
- The sauropods are depicted with nostrils on their foreheads (this was because the nasal openings on the skull were located there, so it was assumed the nostrils were there as well), but nowadays a position near the tip of the snout as with most dinosaurs is considered far more likely (it was later pointed out that in all land vertebrates the nostrils were located in front of the bony nasal openings and not on them).
- 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, a recently-discovered skin impression of Hesperosaurus has shown stegosaur plates were covered in horn rather than skin.note So much for the scene where the Stegosaurus changes the color of its plates by flushing blood into them. And then in 2014 came "Sophie", the most-complete specimen of Stegosaurus to date, which suggests that Stegosaurus's neck was longer than previously thought.
- 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.
- Plesiosaurs gave birth to alive newborns in water just like the fish-like 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, and even that's pushing it. 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. Additionally, it should have a fluke on its tail, as should the Cryptoclidus.
- It's now considered more likely that plesiosaurs such as Cryptoclidus swallowed stones to help grind up food items rather than for use as ballast; in some cases, the stones made up less than one percent of the overall predicted body weight of the animal, and so would have been of very little use to weigh the animal down.
- Ophthalmosaurus could actually give birth to more than five pups at a time; apparently at least eleven.
Giant of the Skies
- The 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 Ornithocheirus was based on a specimen now assigned to 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 Iguanodon" from the fourth episode would probably be placed in the genus 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.
- Recent studies have shown Utahraptor was a more bizarre dromaeosaurid instead of the giant version of Deinonychus that was portrayed in the episode. For starters, it had a bulky body with relatively short hindlegs and tail, making it the raptor version of a bulldog, and its jaw had a procumbent shape similar to Masiakasaurus.
Spirits of the Ice Forest
- Some argue that Leaellynasaura needs plumage. It also might have actually had a really long tail, although it's not clear if these long-tailed fossils belonged to Leaellynasaura or a different, but similar animal.
- More recently, it's been suggested that the supposed large eyes of Leaellynasaura were actually just because it was a juvenile specimen rather than an adaptation for low-light conditions.
- The "dwarf allosaur" seen in this episode was inspired by a single ankle bone found in the 1980s, which was tentatively attributed to Allosaurus for lack of a better genus to place it in. The researchers were not particularly convinced themselves that it was Allosaurus, what with being smaller, from the early Cretaceous rather than the late Jurassic and from Australia rather than North America; let alone, that it was an exact scaled-down replica of the North American dinosaur as the show portrayed it. An Australian theropod dinosaur that matches the ankle bone in size and age, Australovenator, was described in 2009. It also had longer arms than Allosaurus, with devastating claws.
- If the "dwarf allosaur" was indeed Australovenator then it may not be an allosaurid at all, as some evidence suggests megaraptorans (the group of which Australovenator belongs to) are coelurosaurs, which also include Tyrannosaurs.
Death of a Dynasty
- The evidence for female 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. Also, while recent papers suggest most of tyranosaurus was covered in scales(small amounts of feathers are still a possibility), the scales themselves where tiny, more akin to those seen of a bird's foot than the thicker, lizard-style scales seen in the show. The snout is also believed to have had thick keratainous scales on it, too, which was absent.
- The giant pterosaur 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. In March of 2018, the notion that only azhdarchids were left at the time was completely decimated, as several genera of pteranodontid and nyctosaurid pterosaurs were discovered in Morocco strata that were dated to 67 million years. Additionally, not all Maastrichtian pterosaurs (even azhdarchids) were giants.
- The body shape of the Quetzalcoatlus is more akin to the old reconstructions◊ of the species with a short neck, sprawled posture, and Pteranodon-like crest, very different from the modern view, with a much flatter and frontal crest, erect stance, and massive head mounted on a long neck.
- It's been theorized that Triceratops and 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 recent studies.
- The accompanying book briefly mentions the possibility that Anatotitan is synonymous with 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.
- The generic raptor is simply identified as a "dromaeosaur", because at the time, there wasn't a named dromaeosaur species that was known to have existed alongside Tyrannosaurus; now there are known to be at least three (Dakotaraptor, Acheroraptor, and one unnamed species from New Mexico).
Walking With Beasts:
- Debatable with the brief shot of a tamandua, likely meant to represent Eurotamandua from the Eocene of Messel, which was initially identified as an anteater. More recent studies indicate that it probably wasn't an anteater 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 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 couldn't support itself on land.
- 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 mesonychids, and modeled after them. However, later phylogenetic studies indicate that it might have actually been a close relative of 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 proof that other sabertoothed cats did.
- The Deinotherium model follows the theory that deinotheres had shorter trunks than elephants. This was based on the fact that deinotheres separated 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 was 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, the 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 had trunks as short as depicted in the show◊, the animals would be almost incapable of drinking without getting partially submerged in water.
- There is increasing evidence that Australopithecus is not an ancestor of Homo at all, but a more vegetarian offshoot from a common ancestor, that eventually led to the specialist vegetarian genus Paranthropus. The last common ancestor of Australopithecus and Homo might be Ardipithecus (named from fragmentary remains in 1995, a much more complete specimen, called "Ardi", was unveiled in 2009) or an even earlier genus. At any rate, the adaptation to bipedalism must have appeared already in the primitive East African jungle and was unrelated to its clearing and transformation in savanna. "Next of Kin" (as in Next to our Kin) still makes for a great description of Australopithecus, though.
- 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 (S. populator) in the episode had not evolved yet when the show was set.
- At the time the episode was produced, scientists believed that sabertooths had displaced terror birds as apex predators with their arrival, hence their depiction as scavengers. However, it is now considered more likely that the terror birds were still able to remain as apex predators in competition with the sabertooths. Also, the species would have been Titanis in reality, but a theory presented at the time was that Titanis was a synonym of Phorusrhacos, which is mentioned in some supplementary material.
- Although it was suggested at the time by some that Megatherium and other giant ground sloths may have occasionally hunted or scavenged, this idea isn't taken seriously anymore based on lack of evidence.
- Ancient DNA studies have found that Europeans retained dark skin tones until the arrival of paler people from the Middle East and Siberia about 7,000 years ago. This means the episode's Homo sapiens should be of noticeable darker complexion than the neanderthals, some of whom were red haired.
- The interpretation of the Jersey cliffs as killing sites where neanderthals drove mammoths over the edge and butchered them below has been questioned. The mammoth bones might have just rolled downhill and accumulated there naturally, long after their owners died.
Walking With Monsters:
- The Giant Spider in the Carboniferous was based on Megarachne, which ultimately turned out to be eurypterid ("sea scorpion") rather than spider. This was actually an error found out during production, but at that point it was too late to change the model (since the story hinged on Megarachne being a spider), so they just avoided naming the specific animal, opting instead to calling it a generic "mesothelae".
- 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 Dimetrodon and its herbivorous "twin" 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, Angry Guard Dog-looking Gorgonopsid from the show has scent glands (a typical mammalian feature).
- The armoured plant-eating near-reptile 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, Argentinosaurus, being hunted by the largest land predator, Giganotosaurus. Both have been supplanted since then: New evidence found that 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
- 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, which, similar to Giganotosaurus, did not live at the same time as Argentinosaurus.
- 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.
- The enormously long-necked Tanystropheus was potrayed as capable of losing and regenerating its tail like a lizard. In the past it was indeed suggested by palaeontologist Rupert Wildnote 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 we don't know for sure if it really was such - its body-shape was all but hydrodynamic, and some think Tanystropheus 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 Deleted Scene where female nothosaurs (primitive Triassic sea reptiles related to the more famous plesiosaurs) leave their eggs on the beach at night (see What Could Have Been on the Trivia page). However 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 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.
- Leedsichthys would have had a more smooth head than its bone-plated portrayal in the show. Also, careful examination of its size range puts it at around 16 meters and 40 tons as opposed to 30 meters and 150 tons.
The Complete Guide to Prehistoric Life:
- Othnielia and Leaellynasaura do not appear to be ornithopods, but more primitive ornithischians.
- Page 122 claims that therizinosaurs are known from "a lone species" from North America, probably referring to Nothronychus. Enter the ancestral therizinosaur Falcarius in 2005...
- To quote page 125, "Scientists cannot agree on whether Mononykus was a bird or a [non-bird] dinosaur." The 2010 discovery of the ancestral alvarezsaur 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 "sickle claw◊" on their second toe, suggesting that terror birds may have had that instead. It should also be noted that 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, although the possibility of tyrannosaurids proper being unfeathered was revived in 2017.
- Mere days before the movie premiered, it was discovered that Edmontosaurus had a small fleshy crest on its head. Or at least one species, E. regalis, did (this is the species most likely depicted in the film, as the other Edmontosaurus species, E. annectens, is only known from fossil formations much younger than than the other dinosaur species in the movie).
- A 2016 study suggested that the Alaskan Edmontosaurus may be its own genus, Ugrunaaluk; although a subsequent study in 2017 disputed this.
- A study in 2017 has established Troodon to be a dubious taxon due to being only known from a tooth, a similar case with such dubious taxa as Trachodon or Monoclonius. The same study also re-established Stenonychosaurus as a valid genus again, due to being known from better remains (which were formerly assigned to Troodon). The Troodon in the film would have been better termed as Stenonychosaurus instead.