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A prehistoric revolution

Many dinosaurs were big – Very big. So just how did they manage to support themselves and get around? Brian J Ford thinks he knows – and it could change the way we think of these marvellous prehistoric beasts for ever

Dinosaurs don’t work. They pose a huge problem – the biggest problem that we have ever encountered on land. The immense size of the largest genera places impossible loadings on their extremities. A single limb would have to support many tonnes – this would not be compatible with the agility we associate with dinosaurs. We accept the remains of their footprints without demur, although for such gigantic creatures the imprints that we observe in rocky strata make no sense. The prints are roughly as deep in the layers of Liassic mud as ours might have been, although the high mass of an adult dinosaur would cause it to sink up to its knees. The footprints seem to be those of an altogether lighter organism.

Children were traditionally fascinated by dinosaurs, and in recent years, new dinosaur discoveries have refocused popular attention. Had you said ‘raptor’ to a teenager a generation ago it would have signified birds of prey; try it later and you’ll find it has become clawed and vicious creations from Jurassic Park.

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This interpretation of Spinosaurus aegyptiacus, posted on the jurassicpark forum, is a typical reconstruction of a large carnivorous dinosaur. Each limb would have had to support up to 15 tonnes. It seems incongruous on dry land

Once we celebrated Tyrannosaurus rex; now youngsters are as likely to know about Spinosaurus and Velociraptor. Books on dinosaurs have flourished like never before, from the great National Geographic Dinosaurs to the Dorling Kindersley Dinosaurs Eye to Eye. Television, always eager to capitalise on any commercial trend, was soon to follow. The BBC transmitted Walking with Dinosaurs, and followed that with Planet Dinosaur. There has been an upsurge of enduring interest with the discoveries in North America by Professor Jack McIntosh and now in China by Dong Zhiming, so publishers and programme producers are sinking millions into the subject.

Animatronic dinosaurs were not just manufactured, but went on tour like rock stars. The first such exhibition was of concrete dinosaurs made by Benjamin Waterhouse in 1854 for the Crystal Palace exhibition. Waterhouse was personally instructed by Sir Richard Owen, the greatest dinosaur expert of the Victorian era. And now there are computer games like Dino Hunt – there is no end to the current fascination for the great dinosaurs

Yet dinosaurs make no sense. The most obvious problem to me is the sheer mass of the dinosaur and the modest plantar area of the lower limbs. Compounding this is the bipedal stance that is typical of these gigantic creatures. Today’s heaviest land creatures are the elephant, the hippopotamus and rhinoceros; they sensibly spread the load across four limbs rather than two. This is an obvious evolutionary necessity. And it is worse – and dinosaurs seemingly compound the problem by possessing a tail that is proportionately massive. It is not clear to me how one would calculate the expenditure of metabolic energy required to hold such a huge member horizontal and clear of the ground, but the lack of tail drag-marks associated with footprints in fossiliferous strata substantiates my view that little ground contact for the tail was normal for dinosaurs. In every reconstruction, they hold their massive tails aloft. This would have consumed a high proportion of the energy input from their diet. It runs counter to evolutionary theory.

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In this revised image, I have shown it immersed in water to the shoulders. The tail becomes buoyant and the mass of the body is supported by the water. The loading per limb would be less than 1 tonne – and would be reduced to zero if the dinosaur floated in water like a present-day crocodile.

We thus have a set of factors that makes the largest dinosaurs seem impracticable as a product of evolution. They are massive, whereas their surviving spoors suggest that they cannot have been so heavy or they would have sunk into the mud across which they walked. They also developed colossal caudal structures which, in conventional portrayals, are held aloft and do not drag on the ground. Finally, and crucial to my understanding of how dinosaurs are supposed to have functioned, they typically evolved to walk erect, thus forcing the hind limbs alone to bear the burden. An adult T. rex is reckoned to have had a mass of up to seven tonnes, which must have been supported by a single limb when the animal moved.

We may find substantiation of my views on the role of evolutionary pressures in the development of load-bearing anatomy by a looking at today’s largest land animals. The elephant and, to a lesser extent, the hippopotamus conform exactly to the argument I propose. Their great mass is supported by four legs rather than two. They have tiny tails that impose no metabolic burden. Crucially, the trunk of an elephant is an additional member whose weight has to be supported and you could analogise the elephant’s trunk to the tail of a dinosaur – yet it normally hangs downward and consumes little metabolic energy for support. Indeed, the hippopotamus and (to a lesser extent) the elephant find one practical answer to supporting their body mass, for they often resort to partial immersion in lakes or rivers where the displacement of water can help to reduce the load on their limbs. The hippo is now categorised as a semi-aquatic mammal.

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The physics of the brachiosaurs makes far more sense in an aquatic setting. This reconstruction by Richard Hubbert fits the current proposals well, though one hopes that readers will turn a blind eye to the angiosperms in this view.

Although both of these creatures have diminutive tails, there are other large animals that are equipped with examples of dinosaur-like proportions – present-day reptiles. Monitor lizards, culminating in the Komodo dragon (Varanus komodoensis) have substantial tails though even the largest is far smaller than a dinosaur’s. Dinosaur footprints are those of a walking creature and there is no sign of the tail touching the earth. I have observed monitor lizards in Borneo, Central America and elsewhere and they do not always hold the tail free from the ground. The trail of the Komodo dragon is characterised by a deep groove left by the tail dragging along the ground. Crocodilians, notably the salt-water crocodile (Crocodylus porosus) can weigh up to one tonne and possess truly gigantic tail structures which can be up to one-third of the body mass. These tails also drag along the ground, for they are too massive to be held aloft. A few weeks ago I was observing crocodiles in Costa Rica; the spoors that the animals leave behind them feature the clear signs of this great caudal mass dragging along the ground.

Crocodiles are the only present-day creatures that compare with dinosaurs and for most of their lives, apart from times when they haul themselves out onto the bank, they inhabit an aquatic environment. It is the displaced water that bears the weight of the tail, for this is the organ which primarily helps the animal to swim. This, I postulate, provides the answer to the paradox of the ungainly gigantic dinosaurs – the only reasonable solution to the problems that they otherwise pose.

Photo of A prehistoric revolution 5I am now certain that the dinosaurs were primarily aquatic creatures.

Let us see how the physics stacks up.  An African elephant weighs around eight tonnes. It keeps three feet on the ground when walking; so each limb must support some 2.6 tonnes.  Of the rhinoceros species, Ceratotherium simum is the largest and weighs up to 4.5 tonnes. Each limb thus has to support 1.5 tonnes. The adult hippopotamus (Hippopotamus amphibious) weighs some seven tonnes and thus each limb comfortably supports a weight up to 2.3 tonnes.

The effects of immersion in water are dramatic. Animal tissues, being predominately composed of water, may be regarded as of neutral density for this discussion and a large mammal that is 90% below the water level will exert proportionately reduced loading on the limbs – from about eight tonnes to 800 kg for the elephant, from seven tonnes down to 700 kg for the hippo. Similarly, a large crocodile that is scarcely able to stand on its own feet on land becomes effectively weightless in water. In the real world, a crocodile is most typically observed with only the top of the head exposed. In terms of metabolic efficiency, walking on land for a crocodilian can be seen as a costly indulgence.

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Current interpretations of Spinosaurus confirm it lived near water, plunging in its head to find food. In my view it was an aquatic dinosaur and lived largely immersed in water where its fish diet was abundantly available

We now turn to dinosaurs. Volumetric analysis of scale models provides a helpful indication of the effects of an aquatic habitat on the physics of a large extinct reptile like T. rex. The mass of an adult is believed to be as much as much as seven tonnes. I find that the head and shoulders occupy roughly 15% of the volume of the entire animal. Partial immersion in the aquatic surroundings that I now postulate sets the figures into an interesting context; the loading per limb is reduced to 1050 kg in total, or 525 kg per limb when standing. The largest dinosaur yet discovered, Bruhathkayosaurus, was a quadruped weighing some 120 tonnes. Each limb must have supported 60 tonnes when standing, 80 tonnes when walking. Yet this creature, if immersed in water so that only its head and neck are exposed, would have exerted less than five tonnes per limb when standing on all fours, rising to 6.6 tonnes when walking.

The anatomical adaptations we see in these species are consonant with that I propose: they have a large and bulky body with a huge and muscular tail. The mass of the abdomen is immaterial when it is customarily submerged, whereas the nature of the tail fits well with its use as a powerful organ of propulsion and steering for a swimming dinosaur.

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Conventional images of large dinosaurs like this Brachiosaurus in an arid desert (from the ProGenesis web site) exemplify the paradox. I contend that the dinosaurs were supported by a watery environment and the mud on which they lived was the lake bed

The diminished forelimbs are equally well accounted for by this view. In land animals, like the elephant, hippo and rhinoceros, each of the four limbs is load-bearing and evolutionary pressure has been against the reduction in size that we observe in flesh-eating dinosaurs like Tyrannosaurus. If the large dinosaurs are conceived as primarily aquatic, however, then the specialisation of the forelimbs would be towards manipulative dexterity. The fact that the limbs became foreshortened is entirely reasonable: animals like to inspect their food as they eat, and holding it closer to the face is normal behaviour. Conventionally conceived, the small forelimbs of T. rex make no sense – however, if we envision the animal as an aquatic carnivorous species, this adaptation becomes entirely reasonable.

Long-necked genera such as the brachiosaurs and the more recently-investigated Bruhathkayosaurus were herbivorous, and their evolutionary constraints were different. Since plants do not move away when attempts are made to prey upon them, and because leaves would have been eaten en masse and not painstakingly pulled apart prior to consumption, there is less evolutionary impetus towards increased manipulative facility for the forelimbs. Our modelling suggests that a 40 tonne brachiosaur could have weighed a mere 3-4 tonnes above the level of the shoulder. The body mass in water is of near-neutral buoyancy and can thus be provisionally discounted, so this reduced mass is all that has to be borne by the limbs. Had only two supporting limbs evolved, as in the case of the carnivorous genera we have already considered, this loading on the limbs would have been as little as one tonne per limb – very similar to that of a present-day elephant. The mass of the elongated neck, necessarily evolved for an animal specialised for grazing on the foliage of tall trees, would have impelled these genera to evolve towards a four-footed stance. Only through this means could the load factor on the individual limbs remain within the constraints that can be calculated for the other heavy animals we have examined.

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Brian J Ford used volumetric analysis of scale models, and measurements from surviving skeletons at Cambridge and London, to investigate the loadings on the limbs of dinosaurs on land and in an aquatic environment

This concept offers an interesting revision of the many artists’ impressions of large dinosaurs with which we are familiar. The picture from the ProGenesis web site (image 1) shows brachiosaurs abandoned in the middle of a vast and arid plain. They are depicted standing on dried, cracked mud in a desert wilderness. Now apply the view I here advance – envision the scene instead as a shallow lake in which the water supports the weight of the animals. The mud eventually formed the layers of Liassic limestone, in which state it is certainly dry; but at the time it was, in my view, mud at the bottom of interminable shallow lakes. With water flooding the scene in your mind’s eye the picture suddenly makes sense; the scene as originally depicted now seems unrealistic and impracticable.

We have been calculating the likely loading upon dinosaur limbs with and without water and in each case the realities revealed by physics become far more plausible when the bulk of the animal is supported by the buoyancy of partial immersion. My colleague Richard Hubbert has used his skills as a graphic artist to provide ‘before’ and ‘after’ views that set my proposals in context. The scene is far less incongruous when the dinosaurs are half-submerged. Set in this new context, they suddenly make sense.

This revised hypothesis rationalises the paradoxically shallow nature of their footprints in soft mud. Investigations have modelled the consistency of mud in which such shallow footprints can have been impressed, and force us to conclude that closely limited constraints must have applied: the mud needed to be exactly of the right consistency for the footprints to form successfully. It has regularly been concluded that normal alluvial mud would have been so soft that large dinosaurs would sink in deeply and become trapped. In fact, there are widespread dinosaur footprints from large and small species and this variety of depth of impression is not seen. These considerations perfectly fit the concept of a dinosaur that is buoyant in water.

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Research on fossilised footprints at Manchester University concludes that large dinosaurs would have become stuck in deep mud and die. The tracks are easier to explain if the animals were partially buoyant in an aquatic environment

The bulk of the massively muscular tails would have been impractical as depicted in the conventional graphic images. The abundant footprint fossils do not show tail dragging, and adding water to the artist’s impressions makes additional sense from this point of view. There has also been controversy over whether dinosaurs were poikilothermic (their body temperature equilibrating with the environment) or homoeothermic (controlling their temperature through their metabolism). Some research leads to the conclusion that large dinosaurs had a constant body temperature – but this does not mean they were homoeothermic, as current opinions would have it. As primarily aquatic creatures, they would have been buffered against rapid thermal change and their bodies would be close to the temperature of their watery environment. Thus, dinosaurs could have had a steady internal temperature without any need for its metabolic regulation. The mean water temperature during this era adds a final substantiation – it was 37⁰C, the present-day metabolic temperature of the homoeothermic human species.

Current scientific research also fits my proposals perfectly. Spinosaurus was a 15 tonne dinosaur with a large sail-line fin running along its back. If it was aquatic, as I propose, then the fin would have acted as a thermoregulator if heat from the surroundings needed to be shed. Investigations of Spinosaurus in Milan in 2009 subjected the snout to x-ray computed tomography and found that the dinosaur may have been equipped with pressure sensors like those found in crocodilians. The researchers conclude that the dinosaur would have been able to dip its head into water, and use these sensors to catch swimming prey that would otherwise be invisible. A recent BBC television reconstruction shows Spinosaurus wading along and dipping its head into a stream to catch fish, in exactly this way. Clearly, it makes more sense if the dinosaurs were aquatic, and scooped up fish as they swam.

Next, in 2010, an international group based in China analysed the composition of isotopes of the oxygen in the phosphatic remains of Spinosaurus and found the ratios to be close to those seen in present-day crocodiles and turtles, which leads to the inevitable conclusion that they might not have been land-dwelling dinosaurs at all, but could have been semi-aquatic. I take it further still – they, and all gigantic dinosaurs, evolved to live their lives supported by the buoyancy of water.

Dinosaurs were not the lumbering monsters, teetering about on an arid landscape and burning huge amounts of metabolic energy to support both their bodies and their tails. They evolved when the world was largely covered in vast shallow lakes, the remains of which have come down to us as layered Liassic limestone. They used the water to support their mass, buoy up their tails, regulate their temperature and provide a habitat for their food. That chase of a car by T. rex in Jurassic Park is a result of that popular myth of the terrestrial monster. Without a watery environment dinosaurs do not make sense.

This may also provide a reason for their extinction. The era following the age of the dinosaurs was the period when the continents drifted towards their current positions. Mountain building was active; the vast shallow lakes were at an end and the dinosaurs’ aquatic environment disappeared. The era of the Cenozoic that followed was also a time of cooler climates, which weighed against large reptiles without an aquatic thermal buffer in which to survive. During the Cretaceous era when the largest dinosaurs flourished, oxygen levels were at an all-time high of more than 30%. The enormous plants of the time would have favoured the production of atmospheric oxygen, and this would have favoured the metabolism of gigantic creatures. But during the following millennia, oxygen levels dropped to half this level. The survival of giant animals would have immediately been compromised.

There are many controversies that remain, yet most of the paradoxes that surround the study of the dinosaurs are resolved by making this change in concept. Dinosaurs look more convincing in water, and the physics stands up more soundly. All the while we were speculating in science on those remarkable creatures, this single, crucial factor eluded palaeontologists: dinosaurs were aquatic.

Brian J Ford


  1. David C. Bernvi

    I’m not a specialist in anyway. It seems to me that both conventional science published and Ford’s hypothesis not fully studied in the same manner may be right. As with Hominids, the subject of bipedalism might have arisen from a semi-aquatic state. It’s not a far-fetched idea. The reality is probably something in between.

    The discussion is on a similar levels as nature vs. nurture.

  2. A late comment, just to show the depths to which this story can sink (along with the dinosaurs). Over the Easter period this story was covered on the BBC Radio 4 morning news programme “The Today Programme” and the coverage was totally supportive of the concept. The proof which was offered was that “they” said that Galileo was wrong, but the Earth does move. So therefore Dinosaurs were aquatic BECAUSE “THEY” SAY THEY WEREN’T. Honestly, if you’ve got to resort to the Galileo defense then you’re devoid of any sensible argument. A classic examople of what happens to science when it’s discussed in the media by people who have no idea what they’re talking about.

  3. Galileo’s Square-Cube law shows that size matters. This is one of the fundamental concepts in all of science, and yet it is one that most paleontologists refuse to talk about since it reveals that there is something odd about dinosaurs being so large. Brian Ford has reverted back to the old idea that the larger dinosaurs must have waded in the water as a means of reducing their effective weight, yet this hypothesis conflicts with the considerable amount of evidence showing that dinosaurs were completely terrestrial animals. Thus we have a paradox.

    Science is the search for the truth based on the evidence. Yet sometimes the evidence seems to contradict itself. When the evidence seems to contradict itself, there is nothing to gain in taking one side or the other when both sides are flawed.

    Rather than cherry pick the evidence that might supports your side, real scientists are willing to try to see the other person’s side or look for a new hypothesis as they strive to account for all the evidence. Brian Ford may be ignorant of the evidence showing that dinosaurs were completely terrestrial, yet the people belittling his hypothesis are just as ignorant of the fundamental physics showing why large dinosaurs are a scientific paradox.

    I hold a master’s degree in physics, taught college physics for nearly two decades, and I solved the large dinosaur paradox years ago. My theory, the Thick Atmosphere Solution, accounts for how a fluid can provide a buoyancy force so that the dinosaurs could grow so large while still accounting for the evidence showing that dinosaurs were truly terrestrial animals.

    The Thick Atmosphere Solution solving the dinosaur paradox is a major conceptual breakthrough. Yet to be a part of this new scientific movement one has to Google these topics and then spend time doing research. For science to move forward, we need people who are willing to objectively look at the evidence rather than just give their hardheaded opinion.

  4. There would have to be one heck of a lot of shallow water next to vegetation to support the great number of dinosaurs required to perpetuate the species! Great April Fools joke!

  5. Dinosaurs, like you and I, suffered from a variety of skeletal ailments. Some of these, such as diffuse idiopathic skeletal hyperostosis (DISH), affect a number of large dinosaurs such as sauropods, ceratopsians, hadrosaurs, and tyrannosaurs, resulting in the fusions of vertebrae. DISH occcurs in the back, but especially the mid-tail region and is related to the stresses put on the tail by its own weight.
    I find fresh water particularly bouyant when I am in it, and I assume (with confidence) that Mesozoic fresh water was equally as bouyant for “aquatic” dinosaurs. An “aquatic” Tyrannosaurus, hadrosaur, ceratopsian or sauropod would enjoy the benefits of being supported by water. Why then do we continually find examples of DISH, and other paleopathologies in these and other “aquatic” dinosaurs. If their tails are supported by water, that stress-related type of osteopathy would not develop.
    Ankylosaur fossils in freshwater deposits here in Alberta are always found upside-down, because the weight of their armor is enough to turn them over as the carcass bloats and floats. The carcass then sinks to the bottom as the gasses of decay burst out of the body cavity. Or…….. did “aquatic” ankylosaurs live by swimming upside-down (thereby fully exposing their naked bellies to predators) and their well-developed armor protect them from the attacks of nibbling fish……….

  6. I don’t think I need to input my own refute to this article, but I’m posting to concur with all of the legitimate paleontologists who did not fail to catch the conjecture in this essay.

  7. Oh God, I hope this guy knows not ALL dinosaurs were gigantic. Raptors, compsognathids, scansoriopterygids, etc…

  8. I’m faced with a related problem, and was looking into all of this earlier today.

    The problem I’m specifically faced with is joint pressure on large robots. But it had me thinking about the T-Rex walk cycle, and the inherent problems it’s faced with.

    Someone mentioned the Manchester research. I’ve been trying to get their actual data for about a year now, but haven’t had any luck getting someone to return my emails. So here’s GaitSim, which was used for the Manchester research on T-Rex gait, can be downloaded here.

    Only problem is that the T-Rex and Allosaur models don’t appear to be right. Their gaits are visibly wrong.


    Maybe they require special setup though. Has anyone corroborated the Manchester gait research?

    -Chilton Webb

  9. I guess those 100 meter tall trees we see in the Pacific Northwest don’t exist either, because their trunk loading is totally unsuitable for a terrestrial plant. They must be aquatic.

    Good grief. Why is this getting serious coverage again, with no attempt to ask credentialed researchers who work on these fossils whether any of Mr. Ford’s assertions are valid? That’s journalism 101, and I’m saddened that it’s not being followed here.

  10. The comments on dinosaur footprints in this article represent an embarrassing misunderstanding of the science of ichnology. It’s difficult to know what to say, except the author is obviously ignorant of the fundamentals of the discipline and must have ignored the literature completely.

    Any chance of a reference for the Manchester research please?

  11. Jason Loxton (Central Michigan University)

    I would like to thank Professor Ford for providing a fantastic teaching example for my Historical Geology classes (I am going to use it tomorrow!). Many people–sadly even students at the beginning of term–seem to think that paleontologists simply make up just so stories (and that anyone’s guess is as good as anyone else’s), but the predictions made by hypotheses like this show that statements about the ecology and behaviour of fossil organisms are eminantly testable. Aquatic dinosaurs? Surely we’d expect a prepoderance of articulated fossils preserved in marine or laccustrine environments. (We don’t find them there.) Surely their anatomy ought to be designed for aquatic motion. (It isn’t.) Surely there ought not exist large crocodillian and marine reptile competitors occupying the same aquatic niche space.(There are.) Surely most track ways ought not occur in terrestrial sedimentary environments. (They do.) Etc.

    In addition to demonstrating how one can go about checking historical hypotheses, Prof. Ford has also provided an first-class lesson on why peer-review and domain expertise matter (and why we ought not get our science from The Telegraph!).

  12. So strange that he cites the isotopic evidence that supports Spinosaurs as living near water (or at least that they ate a lot of fish), but doesn’t consider why other dinosaurs /do not/ have the same isotopic mixtures.
    Seems like cherry-picking, if it fits, it counts, if it doesn’t fit, ignore it.

  13. Thomas R. Holtz, Jr. (http://www.geol.umd.edu/~tholtz)

    In addition to the comments above, I had to wonder what on Earth the author was doing thinking that a graphic from “ProGenesis” represents traditional scientific thinking. A quick websearch finds that ProGenesis is a now-defunct creationist site! Furthermore, a quick websearch would have found the following open access journal article that discusses actual scientific research on the paleoenvironments of these dinosaurs: http://www.plosone.org/article/info:doi/10.1371/journal.pone.0012553

    The author of this essay is apparently unaware that there exists a vast body of literature and both field and laboratory research that goes into such topics as: paleoenvironmental analysis and depositional setting; taphonomy (the conditions of burial for body and trace fossils); biomechanics and functional anatomy; and so forth.

    Yes, dinosaur science is fun. But it is also science. And you have to learn the details of the field before proceeding, or you wind up making bone-headed mistakes such as the ones here.

  14. Komodo dragons keep 80% of their tail off the ground when walking. Other varanids do similarly, or more. The same is true for most other lizards when walking (or trotting). The only reason any of the tail drags at all is because the sprawled/semi-sprawled limbs do not provide enough height off the ground. If Komodo dragons held their hindlimbs erect, then the tail would not touch at all. Dinosaurs may have had thick and heavy tails, but those tails were full of metabolically active muscle. They could literally pull their own weight. Also, unless you are talking about gharials, a crocodile is not “scarcely able to stand on its own feet” on land. Most species are fully capable of walking, trotting and even galloping on land. Overland journeys of many kilometers have been recorded for Nile and Mugger crocodiles. I think you might be underestimating the abilities of modern animals here.

  15. Robert Boessenecker

    Some additional comments – as Darren indicated, there are many cases of dinosaurs preserved in dry conditions such as arid deserts and, in particular, buried in sand dune deposits. Additionally, there have been some dinosaurs identified as burrowers, with their skeletons preserved inside a burrow. Certainly some dinosaurs are preserved in water-deposited rocks, and even in marine strata – but any theory suggesting an aquatic habitus for dinosaurs falls flat on its face, because the sheer majority of dinosaur fossils are in terrestrial rocks rather than in marine sediments. Instead, in marine rocks, there are marine reptiles sensu stricto – ones that actually have flippers (and, are not found in nonmarine sedimentary deposits). In order to promote this wild bit of guess work (I won’t dare call it a hypothesis), you not only would have to assume that every dinosaur paleontologist in history was either insane or stupid – but also that the entire field of sedimentary geology be made up of blithering idiots who can’t tell marine rocks from
    non-marine rocks. The possibility that either we’re all a bunch of morons is as remotely low as the field of cell biologists misidentifying animals as having plant cells and vice versa.

    Secondly, there is an enormous volume of research on fossil tracks and tracemakers, based on actualistic work of modern trackways and work on fossil trackways, and in combination with good sedimentology, it is relatively easy to figure out the depositional environment, wetness of the substrate, and so forth. Paleontologists have identified all sorts of tracks that are clearly made in shallow water, where the toes scrape the bottom and form long, raking furrows – quite unlike the standard type of track clearly delineating a foot that was pressing into drier substrate. Furthermore – there are rare footprints identified in some dune deposits representing dinosaurs walking around in loose, dry sand, which forms a very different type of footprint. One problem that makes it extremely easy to confuse or mischaracterize tracks is the fact that they are often exposed on a bedding plane, but we rarely get the opportunity to look at them in cross section: As Neil Clark points out, tracks become pushed down into the sediment, and affect the sediment vertically quite a bit – the rock exposure we discover in the field may be from any vertical part of that affected rock, and its ichnological features should be expected to change from bottom to top.

    Thirdly, with the exception of aquatic birds (e.g. penguins, some flightless alcids, plotopterids, hesperornithiforms) there aren’t any dinosaurs that have been identified to have flippers, tail flukes, or even the basic muscle attachments necessary for caudal undulation (e.g. crocodilians have large bony processes that stick out laterally for muscles at the base of the tail to move it side to side; these bones are, in comparison, poorly developed in dinosaurs). On the contrary, there are many other marine reptile groups with caudal flukes and paddles/flippers (Plesiosaurs, ichthyosaurs, mosasaurs, etc.).

    Fourthly, there are dinosaur coprolites with wood preserved in them. The list goes on and on, but I have to get some sleep. I’m sure others will think of additional non-supporting evidence.

  16. Interesting read. The notion of an aquatic way of life seems so obvious now.

  17. In addition to all the above comments, dinosaur footprints that we see are not always on the original surface, but may be a transmission effect of the weight of the dinosaur down to over a metre in depth below the original surface the dinosaur was walking on. The deeper the transmission, the shallower the effect of the footfall, hence the shallow footprints. The depth of the footprints and the existence of the footprints also depends on the competence of the sediment on which the dinosaur walks – affected by water content, grain size and type, consistency. There is no problem with big dinosaur leaving the footprints they do. I can only assume that this is an April fool’s prank?

  18. You seem to labouring under the assumption that palaeontologists just ‘guess’ the palaeoecology of these animals to suit some kind of ideology they have in their heads, from reading ‘My First Dinosaur!’ books as kids and watching films with impressive CGI models of _T. rex_. This couldn’t be further from the truth: it’s all based on evidence.

    I totally agree with Darren: anatomically speaking there is just no evidence for an aquatic lifestyle in dinosaurs, except that which we see in birds.

    As for large dinosaurs not being able to support their own neck and tails… Go check out a really long suspension bridge: same principle. This stuff is all in the literature and, as Darren says, is really not a problem when comparing it to extant animals.

    My final point, and one you completely ignore. Sedimentology is crucial to understanding the environments in which these animals lived. It has nothing to do with preconceptions and everything to do with evidence. Yes, some dinosaurs evidently lived near water, but a lot of them lived in arid areas like deserts. Just to say ‘I reckon this mud would have been at the bottom of a lake’ does not cut the mustard. Lacustrine deposits are totally different to deposits representing arid environments.

    ALL of these things are factored in to come up with the picture we have of dinosaurs today.

  19. “Dinosaurs don’t work. They pose a huge problem – the biggest problem that we have ever encountered on land.”
    Not according to the people who actually study them.

    “The immense size of the largest genera places impossible loadings on their extremities.”
    ..and contradicted by papers such as this one :
    Burly gaits: centers of mass, stability, and the trackways of sauropod dinosaurs; Donald M. Henderson; Journal of Vertebrate Paleontology, Volume 26, Issue 4, 2006

    “A single limb would have to support many tonnes – this would not be compatible with the agility we associate with dinosaurs.”
    STRAW MAN #1
    What “agility”? Large sauropods were unlikely to have been agile!

    “We accept the remains of their footprints without demur, ”
    No, we don’t: We engage in extensive research into how such footprints are formed and model them using extant organisms.

    “although for such gigantic creatures the imprints that we observe in rocky strata make no sense. ”
    Why on earth not? We can and have studied the structure of such footprints in “rocky strata” in great detail.

    “The prints are roughly as deep in the layers of Liassic mud as ours might have been,”
    They are? Where are the calculations to support this assertion?

    “although the high mass of an adult dinosaur would cause it to sink up to its knees. ”
    How on earth does he know? Where are the calculations to support this assertion?

    “The footprints seem to be those of an altogether lighter organism.”
    …which, as dinosaur skeletons were highly pneumatised, seems very likely.

    Need I go on?

  20. I look mainly at extant invertebrates but even to me this doesn’t make sense; “the paradoxically shallow nature of their footprints in soft mud” isn’t a paradox, it just indicates (for example) that mud was less soft. Also, if alluvial mud was too soft for dinosaurs to walk on it, the lack of prints might simply mean they didn’t enter areas they couldn’t get out of. I wouldn’t normally comment outside my field but this is poor science poorly argued and dressed up in physical results chosen to fit the hypothesis.

  21. Fossils – the clue is in the number of fossils – which are the product of sedimentation. Sedimentation involves water – ergo creatures that are fossilised were near water when they died – lots of fossils tell you that there was lots of water. There are lots of dinosaur fossils. The land/water distribution during the Triassic and Jurassic meant that there were many more shallow seas and lagoons than there are now. These animals weren’t land or sea – they were littoral – spending some time on land – laying eggs at least – but everything else about them tells you that they were up to at least their hips in water – even the T Rex – air sacs, crocodile shaped and streamlined with massive back legs to kick along the bottom – Brian, there are those that can’t even see the aquatic phase in our own species so it is a big ask to get them to believe anything about the prehistoric world that the BBC didn’t provide the pictures for. Good luck with this.

    • Ouch! Even first year undergrad geologists could pick this comment apart. I think you need to read up on how sedimentology and fossilisation actually works…

      • Animals die, stuff falls on top of them – and that most frequently happens in water – if you are teaching your undergraduates something different about the essence of fossil formation you might want to keep that to yourself

        • That only proves that the dinosaurs were fossilized in water, and that there is a bias toward finding more fossils near the water because there you have a better chance of finding fossils, not that they were intrinsically aquatic. Could we extrapolate this and say that Pteranodon longiceps was an aquatic animal based on where they were found? What about Pachyrhinosaurus lakusai?

          • Wow, I mucked that up. What I meant to say is there is a bias for finding fossils near water because rapid sedimentation is a more common occurrence, not because the dinosaurs or reptiles that left them were aquatic.

  22. An amusing idea, but totally flawed scientifically. If these ideas are meant seriously, they are an embarrassment. Most dinosaurs were terrestrial. Trackways confirm this – there are numerous nice clear sharp prints preserved in sediments that were not underwater a the time they were formed. Sauropods, and many other dinosaurs, had numerous weight-saving measures, including an air-sac system that permeated much of the skeleton and potentially decreased their density substantially. Some dinosaurs are clearly preserved in terrestrial sediments – e.g. Velociraptor and Protoceratops trapped together in desert sands in Mongolia. Spinosaurs might well have had pressure-sensing cells in the snout, but these animals are one of the few groups of dinosaurs, which are believed to be specialist fish-eaters – this cannot be extrapolated to all dinosaurs. Estimating the mass of extinct organisms using volumes of models and assumed densities is well known to have large error margins and tends to over-estimate body mass substantially. The structure of dinosaurian hands, feet and tails are very poorly adapted for aquatic life in most cases (no webs, no fins – and this is despite several examples of soft part preservation etc. where such structures could have been preserved if they existed). All of this information was freely available to Prof Ford – he only needed to read the literature or talk to a couple of dinosaur palaeobiologists to find out. Either this is a leg pull that should have been published on April 1st, or Prof. Ford has wasted his time and needs to be a little more humble, especially when crossing over into an area where he is not an expert – the huge body of work by geologists and palaeontologists that supports the terrestrial habits of dinosaurs should not be swept aside so dismissively and with so little basis in fact.

  23. Aquatic, swimming and wading vertebrate animals possesses a set of anatomical features that are usually obvious in the skeleton. These features are entirely absent from Mesozoic dinosaurs (with the exception of aquatic birds like hesperornithines). And people who work on biomechanics, body size and musculature in extant animals have never had any need to contradict the view that dinosaurs were terrestrial animals, entirely suited to a successful life on land. Many dinosaur fossils come from deserts and other arid environments. Your model can be rejected in entirety.

  24. A fascinating article that I read with much interest.I am sure that Robert McNeill Alexander would have appreciated this but I think that it was several days late in hitting the press. An early April publication would have been more appropriate.

    Volumetric physics apart, cantilever support mechanisms, adaptations of saurapod pelvis aside, consider chasing your own small child around in a muddy stream? How do the footprints look? WIth part of my weight supported by water, the traction is very limited producing elongated and streaked prints, I guess this would be the norm with the prints that we find
    Or perhaps I have been ‘in too deep’

    Nigel Stevens