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Junk in the trunk: why sauropod dinosaurs did not possess trunks (redux, 2012)

The views expressed are those of the author and are not necessarily those of Scientific American.


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Time for another classic from the Tet Zoo archives: this article first appeared on ver 2 in March 2009 and is republished here with a few additions and improved images.

Trunked sauropods: a hypothetical trunked Diplodocus (and an Asian elephant) at top, illustrated by Robert Bakker, and (below) a hypothetical trunked Giraffatitan, by Bill Munns.

It is the contention of some that the field of Mesozoic reptile research is plagued with bizarre hypotheses. You may or may not agree with me that skim-feeding giant pterosaurs, wind-surfing sail-crested pterosaurs, the ‘terrestrial vulture’ concept of Tyrannosaurus, and crampon-using dromaeosaurs are all, shall we say, unlikely. In some cases the science has been done to smack these ideas down, in other cases it has not. In my opinion, one of the most illogical hypotheses entertained within recent decades is the ‘sauropods had trunks’ hypothesis.

Unlike most tetrapods, the bony nostrils of most sauropods are dorsally located: in diplodocoids they’re located right up over the eyes in a region you might term the forehead. In extant mammals, the species with dorsally located bony nostrils have a proboscis, or trunk. Ergo, sauropods might have had trunks.

Trunked dicraeosaurid, illustrated in 1975 by Gregory Irons for the 1990 book All New Dinosaurs and Their Friends.

This idea is familiar to most dinosaur scientists and afficianados because it’s often trotted out in popular books as one of those things that “might be possible, but we’ll never know, woooo!”. Gregory Irons produced a short-trunked Dicraeosaurus for Robert Long and Samuel Welles’s All New Dinosaurs and Their Friends (Long & Welles 1980), Bakker illustrated a trunked Diplodocus in The Dinosaur Heresies (Bakker 1986, p. 141), as did John Sibbick for When Dinosaurs Ruled the Earth (Norman 1985, p. 7). If there are others, please let me know.

John Sibbick's trunked diplodocid, from David Norman's 1985 book When Dinosaurs Ruled the Earth.

Walter Coombs and the trunked sauropod movement

The trunked sauropod movement is usually said to have started with Walter Coombs’s seminal 1975 paper ‘Sauropod habits and habitats’. Coombs (1975) looked at numerous lines of evidence and concluded that, while sauropods may have entered the water on occasion, they were not amphibious, but were strongly adapted for terrestriality (though, he did note that “Calling the entire … Sauropoda a homogenous group is probably misleading … as the diversity of sauropod morphology probably reflects diversity in habits and habitat preferences” (p. 29)). Thanks to his 1971 article in Nature, Bakker has gotten most of the credit for initiating the terrestrial sauropod movement (Bakker 1971), but Coombs’s far more detailed article was equally important. For the original appearance of the beast below, go here on SV-POW!

"Sauropods are basically alien animals . . . What can be said of the habits of an animal with the nose of a Macrauchenia, the neck of a giraffe, the limbs of an elephant, the feet of a chalicothere, the lungs of a bird, and the tail of a lizard?" (Coombs 1975, p. 29). Borrowed from SV-POW!

Anyway, Coombs (1975) noted that the size, shape and position of the bony nostrils in sauropods “is similar in some respect to mammals which have, or are thought to have had, either a proboscis or at least a very large nose” (p. 6). He does seem to have concluded that a proboscis of some sort was present in at least some members of the group, though he noted that “There is certain reluctance to accept a sauropod fitted with a proboscis because no living reptile has anything comparable to an elephantine or tapiroid nose” (p. 6). Coombs also pointed to the general absence of the required facial musculature in reptiles, and noted that this would be a problem for the trunk hypothesis. We’ll look at this some more in a minute.

Coombs’s proposal was not widely followed – in fact, it wasn’t really followed at all. Long & Welles (1980) were interested enough to get that trunked dicraeosaur drawn in their book, but they noted that “It must be stressed that we will probably never have direct evidence for sauropod trunks, but it is an interesting suggestion, and we wanted to take this opportunity to see just what a sauropod would look like with a trunk!”. Irons’s drawing is dated 1975, so was obviously produced soon after the appearance of Coombs (1975).

Martin and Neave’s big-lipped diplodocoid

During the 1980s and 90s, John Martin sometimes championed the trunk hypothesis, though to my knowledge he never published anything on it: in the world of sauropod research, he is better known for arguing that sauropod necks functioned as mostly immobile horizontal beams* (Martin 1987, Martin et al. 1998), and for his work on Cetiosaurus (Upchurch & Martin 2002, 2003).

* A notion that I and my colleagues totally disagree with, incidentally: see Taylor et al. (2009) and numerous articles on sauropod neck posture at SV-POW!

Little known is that John worked together with a forensic anatomist, Richard Neave of Manchester University, to produce an anatomical model of a Diplodocus with reconstructed soft tissues (Anon. 2000). This model doesn’t actually have a ‘trunk’ at all: instead, it has massive, flexible lips, and its nostrils are shown as being placed posterior to the lips, but not fused with them (a trunk or proboscis is best imagined as a fusion of the narial and lip musculature). That nostril position is pretty interesting, as it’s similar to the position since advocated by other workers (more on this below). Unfortunately there doesn’t seem to be any published information on how Martin and Neave’s model was created, nor on the logic behind it: so far as I can tell, it’s entirely speculative, providing the sauropod with lip and snout muscles that are not present in any reptile. The model was featured on TV in a 1996 series produced for children, called The Great Dinosaur Trail.

The trunked brachiosaur

Back in 2008, ace model maker Bill Munns – perhaps best known for his outstanding life-sized Gigantopithecus model – indulged in a bit of speculative model-making and produced another trunked sauropod. Whereas all other depictions have been of diplodocoids, Munns’s model depicts the macronarian Giraffatitan (formerly Brachiosaurus brancai: see Taylor (2009)). Like Coombs, Munns wondered if the dorsally located bony nostrils of sauropods might indicate the presence of a proboscis, and he went as far as providing the animal with a fairly long, elephant-like, tubular proboscis. Cryptozoologist and author Loren Coleman thought all of this was pretty interesting and wrote about Munns’s new model at Cryptomundo. Munns then produced a lengthy discussion of his sauropod models, and of the logic behind them, starting here (he also wrote about the possibility of a proboscis in Diplodocus). I thought it worth pointing out that the trunk hypothesis is not supported by present evidence, and a sort of gentle rebuttal to the idea was featured here at Cryptomundo.

Untrunked and hypothetical trunked brachiosaurs, produced by Bill Munns.

Here, I’m going to expand on these points and show just why the trunk hypothesis can be – in my opinion – fairly conclusively rejected. I’ve always thought that the trunk hypothesis is nonsensical and contradicted by a pile of evidence, and what irks me most about the idea is that it all rests on the fact that sauropods have dorsally located nostrils. As we’ll see, and as is obvious if you look at the proboscides of extant mammals, there’s a lot more to having a trunk that having large, dorsally located nostrils. Here, we go through the various anti-trunk points in turn. Some have been discussed before in connection with the hypothesis, others have not.

Skull shape. Mammals with proboscides or inferred proboscides – I’m thinking tapirs, pyrotheres, astrapotheres, the stem-whale Makaracetus, some amynodontid rhinos, some oreodonts, Macrauchenia, dik-diks, saigas, desmans, sengis and so on – have narrow snouts. More precisely, the premaxillary and anterior maxillary part of the skull is narrow, typically being about half as wide as the back part of the skull (by which I mean everything from the orbits posteriorly). Many proboscideans differ from the aforementioned mammals in that they have strongly modified, shortened snouts and hypertrophied incisor sockets that obscure the ancestral skull shape, but note that proboscideans with unexpanded incisor sockets (things such as Phiomia, amebelodontids, and even juvenile and tuskless modern elephants) are typically narrow across the premaxillae, compared to the width across the cheeks. Given that the proboscis is used for selective foraging, and hence has to be narrow and prehensile at its tip, it follows that it must typically be the ‘extension’ of a narrow snout.

Sauropods are a whole different kettle of tetrapod: their snouts are broad, sometimes remarkably so. In the diagram above, from Paul (1998), note in particular the broad mouths of (A) Apatosaurus, (B) Giraffatitan, (C) Camarasaurus and (D) Diplodocus. Diplodocoids, popularly imagined by those unfamiliar with these animals to have lightly built, narrow, delicate skulls, had robust, rectangular skulls where the mouth was as broad as, or even broader than, the rest of the skull. Macronarians like Camarasaurus, brachiosaurs and titanosaurs had far broader snouts. While a few trunked mammals have broad snouts (deinotheres come to mind*), the fact that there aren’t really any narrow-snouted sauropods weighs heavily against the trunk hypothesis.

* And, yes, I’m fully aware of the controversy over deinothere trunk and facial anatomy.

Morrison Formation sauropods, engaged in high-browsing, as reconstructed by Greg Paul. L to r: Camarasaurus, Barosaurus, Apatosaurus.

Necks! The idea that sauropods might have had trunks seems particularly bizarre given that these animals had already evolved one of the most extreme and remarkable food-gathering organs in tetrapod history: namely, super-long necks. While it has been suggested that sauropod neck length might have been driven by sexual selection (Senter 2007) – an argument which, I think I can say without any bias whatsoever, was effectively smacked-down in a particularly awesome and highly readable piece of first-rate research (Taylor et al. 2011) – and while some workers have argued that sauropod necks were beam-like, largely immobile, and hence overall useless for anything other than feeding off the ground, it is generally agreed that sauropod necks provided these animals with unparalleled vertical and lateral foraging ranges (Taylor et al. 2009). Notably, trunked mammals are almost all short-necked. It looks as if trunks are only evolved when the animals concerned (a) have the required musculature and whatnot and (b) are relatively short-necked. So, we see trunks in such animals as tapirs, rhinos, astrapotheres and so on. A few proboscis-bearing mammals ruin this correlation, such as dik-diks. Then there’s the litoptern Macrauchenia, traditionally depicted with a proboscis, and known to have had a reasonably long neck.

Nevertheless, the ridiculous, hypertrophied necks of sauropods seem to have played the same role that trunks do in the mammals that have them, and it really seems like overkill for both structures to have been present in tandem. This argument is circumstantial, but I still think there’s something in it. Incidentally, I should note here that members of at least one sauropod lineage (Dicraeosauridae) evolved short necks. For the other reasons discussed here, trunks can still be excluded in these animals.

Cranial musculature. One argument that gets consistently trotted out whenever the possibility of sauropod trunks is mentioned concerns the absence of facial muscles in sauropods, and in dinosaurs and reptiles in general. In mammals, a group of muscles ancestrally associated with the upper lip and nose have been co-opted to form a proboscis, including the levator labii, rectus nasi, and caninus (Witmer et al. 1999, Shoshani & Marchant 2001). Unless you’re going to propose something way out there and totally, totally novel (like, say, an amuscular proboscis composed entirely of pneumatic cells, somehow controlled by valves), the total absence of these muscles in reptiles means that they lack the basic equipment required to evolve a trunk. In other words, because the extant phylogenetic bracket (EPB) for sauropods (that is, the extant animals that ‘bracket’ sauropods in the phylogeny – namely, lepidosaurs, crocs and birds) shows that these facial muscles (or anything like them) were absent, it would be an unjustified speculation to infer their presence.

Skull of a modern tapir, photographed at Oxford University Museum of Natural History, by Darren Naish.

The loophole here is that bizarre novelties can arise that violate (if you will) the EPB*. The EBP for ornithischians and sauropodomorphs, for example, shows that cheeks** must be assumed absent, yet various lines of evidence indicate that such structures were likely present in these animals. Cheeks must thus evolved as novelties within these clades (for previous Tet Zoo discussions of cheeks in dinosaurs see Therizinosauroids and Altangerel Perle and Ankylosaur week, day 5: Edmontonia). A similar line of logic could be used for cranial musculature: might sauropods have somehow evolved totally novel musculature that ‘allowed’ the evolution of a trunk?

* For a previous reaction to my use of the phrase ‘violating the EPB’ go here.

** For the sake of clarity, I’m using the term ‘cheek’ here to refer simply to a sheet of tissue that forms a lateral wall to the buccal cavity – not necessarily to a complex, muscular structure like that present in mammals.

In short, no. In, err, long… muscles – particularly big, strong muscles like those involved in any hypothetical trunk – leave visible attachment sites, such as crests, scars, or fossae. These sorts of structures are obvious in extant trunked mammals. In the tapir skulls shown here, you can see obvious lumps and bumps and deep concavities (termed fossae), all of which are associated with the attachment of musculature. Such structures are also present in proboscideans, and also in extinct mammals inferred to have a proboscis (Wall 1980). They are entirely absent in the skulls of sauropods. Also worth noting is that some workers have argued that the bony bars around the nostrils of sauropods appear far too weak to have anchored proboscis musculature (Paul 1987).

You could play devil’s advocate and say that all of this is negative evidence. Well, ok, but remember that we can only infer structures – particularly super-controversial and counter-intuitive structures like sauropod trunks – when we have strong positive evidence. Or, should that be simply ‘evidence’.

Nostril position and facial vasculature. As mentioned above, the sauropod trunk hypothesis mostly came about because most sauropods have dorsally located bony nostrils. As mentioned earlier, the trunk hypothesis has not been widely adopted among dinosaur workers, but – when it has – people have imagined the nasal airway to emerge from the bony nostrils and to travel all the way down the trunk such that the fleshy nostrils are at its tip. Far more typical has been the assumption that the fleshy nostrils were actually located within the bony nostrils, and usually in position somewhere round about the middle or posterior part of the bony openings.

As Witmer (2001) showed, this is almost certainly incorrect, given that, in extant reptiles (including birds), the fleshy nostril is located anteriorly within the nostril region. And, by ‘nostril region’, I mean the area that also incorporates the nasal vestibular vascular plexus (NVVP), a complex mass of richly vascularised erectile tissue that surrounds the fleshy nostril. The NVVP leaves behind various osteological signs for its presence (predominantly foramina and canals for blood vessels).

In sauropods, Witmer (2001) argued that the osteological correlates of the NVVP are located anteroventral to the anterior margin of the bony nostril: in other words, the fleshy nostril and its associated soft tissues were located down on the front part of the snout. This is why newer illustrations of sauropods show them with nostrils that are more anteriorly located than those in older illustrations. The osteological evidence for fleshy nostril position in sauropods is flatly incompatible with the trunk hypothesis.

Cranial neurology. Trunks are complicated, prehensile organs, and as such they require sophisticated muscular control. Knoll et al. (2006) noted that elephants have a huge facial nerve (10 mm wide near its emergence from beneath the jaw joint) that unites with a large maxillary branch of the trigeminal nerve. The same is true of tapirs (Witmer et al. 1999). Evidence for huge cranial nerves is also present in fossil mammals thought to have had proboscides: in Astrapotherium and some amnyodontid rhinos, for example, an enlarged infraorbital foramen (this is the bony opening present on the zygomatic arch, ventral to the orbit) shows that the nerves and blood vessels associated with the snout region were hypertrophied as they are in extant proboscis-bearing mammals (Wall 1980).

At left, endocast of Diplodocus compared with, at right, facial nerve distribution in an elephant embryo. While the facial nerve (nerve VII) is tiny in the Diplodocus endocast, it's huge in the elephant. From Knoll et al. (2006).

Dinosaurs do not have infraorbital foramina, but we can still work out how big their facial nerves were if we have casts of their brains. It is entirely reasonable to assume that, if any other tetrapod were to evolve a proboscis, it also would need specialised, hypertrophied nerves. How do sauropods match up? As Knoll et al. (2006) showed, brain casts of Diplodocus and Camarasaurus show that the facial nerve roots were tiny (1 mm and 3 wide respectively). This demonstrates that the neurology required for a proboscis in these sauropods is emphatically absent. Because Knoll et al. (2006) were only able to get data from Diplodocus and Camarasaurus, they said that the trunk hypothesis remains viable for other sauropods. However, as argued here, other lines of evidence demonstrate convincingly that trunks were absent across the group.

Tooth wear. A reasonable amount of work on sauropod tooth wear has been produced. Little known outside the field of dinosaur research, it seems, is that sauropod teeth are typically heavily worn, with large wear facets produced by abrasion from food (Barrett & Upchurch 1994, 1995, Calvo 1994, Christiansen 2000, Upchurch & Barrett 2000, Sereno & Wilson 2005). Furthermore, inclined wear facets on the labial surfaces (= outside surfaces) of diplodocoid upper and lower jaw teeth show that these dinosaurs were grabbing foliage in the mouth, and then either pulling the head and neck sharply upwards (thereby producing inclined wear facets on the labial surfaces of the lower jaw teeth), or downwards (thereby producing facets on the labial surfaces of the upper jaw teeth). Upchurch & Barrett (2000) referred to this style of feeding as unilateral branch stripping. It is, again, flatly incompatible with trunk presence, because a hypothetical trunked diplodocoid that grabs branches in its mouth and then pulls its head sharply downwards is going to find that branch banging into and/or injuring its proboscis.

Unilateral branch stripping reconstructed for Diplodocus, from Barrett & Upchurch (1994).

The extensive wear on sauropod tooth – indicative of raking or slicing – shows extensive use of the teeth as feeding tools. Again, this seems incompatible with the presence of a trunk, as if sauropods had proboscides, wouldn’t they be grabbing foliage with the trunk tip, and then passing it into the mouth, over the teeth? It’s certainly difficult to imagine how they would be creating heavy wear on the labial sides of their teeth. Note that some titanosaurs possessed guillotine-like jaw edges that (so it has been suggested) might have functioned as pseudo-beaks for slicing off vegetation. Again, this is contradictory with the need for a trunk given that the whole point of a trunk is that it, rather than the jaws, is used to pluck vegetation.

Final thoughts

Elephas and a hypothetical trunked diplodocid, from Knoll et al. (2006).

So, there we have it. I argue that the broad muzzles and super-long necks of sauropods are incompatible with trunk presence. The lack of appropriate facial musculature, the absence of muscle attachment sites, and the presence of small facial nerves all show that sauropods did not, and could not have had, trunks. Furthermore, the data we have on soft tissue nostril position, and on tooth wear, is also completely incompatible with the presence of a trunk. As mentioned a few times in this article, the trunk hypothesis has NOT been widely adopted by dinosaur workers. In fact, it is very much a minority fringe opinion, rarely taken seriously. This rather lengthy appraisal might, therefore, be akin to using a sledgehammer to open a peanut (or whatever the phrase is); nevertheless, I felt it needed doing, in part because a detailed appraisal such as this, involving numerous lines of evidence, hasn’t been produced before. I should finish by noting that this criticism of the trunk hypothesis does not mean that sauropods were necessarily devoid of other interesting, possibly weird, soft-tissue facial structures (by which I mean inflatable sacs, wattles and crests).

For previous Tet Zoo articles on sauropod biology, diversity and behaviour, see…

Refs – -

Anon. 2000. Just when you thought it was safe…… The Dinosaur Society Quarterly Magazine 3 (5), 8-9.

Bakker, R. T. 1971. Ecology of the brontosaurs. Nature 229, 172-174.

- . 1986. The Dinosaur Heresies. New Theories Unlocking the Mystery of Dinosaurs and their Extinction. William Morrow, New York.

Barrett, P. M. & Upchurch, P. 1994. Feeding mechanisms of Diplodocus. Gaia 10, 195-203.

- . & Upchurch, P. 1995. Sauropod feeding mechanisms: their bearing on palaeoecology. In Sun, A. & Wang, Y. (eds) Sixth Symposium on Mesozoic Terrestrial Ecosystems and Biota, Short Papers. China Ocean Press (Beijing), pp. 107-110.

Calvo, J. O. 1994. Jaw mechanics in sauropod dinosaurs. Gaia 10, 183-193.

Christiansen, P. 2000. Feeding mechanisms of the sauropod dinosaurs Brachiosaurus, Camarasaurus, Diplodocus, and Dicraeosaurus. Historical Biology 14, 137-152.

Coombs, W. P. 1975. Sauropod habits and habitats. Palaeogeography, Palaeoclimatology, Palaeoecology 17, 1-33.

Knoll, F., Galton, P. M. & López-Antoñanzas, R. 2006. Paleoneurological evidence against a proboscis in the sauropod dinosaur Diplodocus. Geobios 39, 215-221.

Long, R. A. & Welles, S. P. 1980. All New Dinosaurs and Their Friends. Bellerophon Books, Santa Barbara.

Martin, J. 1987. Mobility and feeding of Cetiosaurus (saurischia, sauropoda [sic]) – why the long neck? In Currie, P. J. & Koster, E. H.(eds) Fourth Symposium on Mesozoic Terrestrial Ecosystems, Short Papers. Boxtree Books (Drumheller, Alberta), pp. 154-159.

- ., Martin-Rolland, V. & Frey, E. 1998. Not cranes or masts, but beams: the biomechanics of sauropod necks. Oryctos 1, 113-120.

Norman, D. B. 1985. When Dinosaurs Ruled the Earth. Marshall Cavandish, London.

Paul, G. S. 1987. The science and art of restoring the life appearance of dinosaurs and their relatives – a rigorous how-to guide. In Czerkas, S. J. & Olson, E. C. (eds) Dinosaurs Past and Present Vol. II. Natural History Museum of Los Angeles County/University of Washington Press (Seattle and London), pp. 4-49.

Senter, P. 2007. Necks for sex: sexual selection as an explanation for sauropod dinosaur neck elongation. Journal of Zoology 271, 45-53.

Sereno, P. C. & Wilson, J. A. 2005. Structure and evolution of a sauropod tooth battery. In Wilson, J. A. & Curry-Rogers, K. (eds) The Sauropods: Evolution and Paleobiology. University of California Press, Berkeley, pp. 157-177.

Shoshani, J. & Marchant, G. H. 2001. Hyoid apparatus: a little known complex of bones and its “contribution” to proboscidean evolution. In The World of Elephants – International Congress, Rome 2001, pp. 668-675.

Taylor, M. P.  2009. A re-evaluation of Brachiosaurus altithorax Riggs 1903 (Dinosauria, Sauropoda) and its generic separation from Giraffatitan brancai(Janensch 1914). Journal of Vertebrate Paleontology 29, 787-806.

Taylor, M. P., Wedel, M. J. & Naish, D. 2009. Head and neck posture in sauropod dinosaurs inferred from extant animals. Acta Palaeontologica Polonica 54, 213-220.

Taylor, M. T., Hone, D. W. E., Wedel, M. J. & Naish, D. 2011. The long necks of sauropods did not evolve primarily through sexual selection. Journal of Zoology 285, 150-161.

Upchurch, P. & Barrett, P. M. 2000. The evolution of sauropod feeding mechanisms. In Sues, H.-D. (ed) Evolution of herbivory in terrestrial vertebrates: perspectives from the fossil record. Cambridge University Press (Cambridge), pp. 79-122.

- . & Martin, J. 2002. The Rutland Cetiosaurus: the anatomy and relationships of a Middle Jurassic British sauropod dinosaur. Palaeontology 45, 1049-1074.

- . & Martin, J. 2003. The anatomy and taxonomy of Cetiosaurus (Saurischia, Sauropoda) from the Middle Jurassic of England. Journal of Vertebrate Paleontology 23, 208-231.

Wall, W. P. 1980. Cranial evidence for a proboscis in Carducodon and a review of snout structure in the family Amynodontidae (Perissodactyla, Rhinocerotoidea). Journal of Paleontology 54, 968-977.

Witmer, L. M. 2001. Nostril position in dinosaurs and other vertebrates and its significance for nasal function. Science 293, 850-853.

- ., Sampson, S. D. & Solounias, N. 1999. The proboscis of tapirs (Mammalia: Perissodactyla): a case study in novel narial anatomy. Journal of Zoology 249, 249-267.

Darren Naish About the Author: Darren Naish is a science writer, technical editor and palaeozoologist (affiliated with the University of Southampton, UK). He mostly works on Cretaceous dinosaurs and pterosaurs but has an avid interest in all things tetrapod. His publications can be downloaded at darrennaish.wordpress.com. He has been blogging at Tetrapod Zoology since 2006. Check out the Tet Zoo podcast at tetzoo.com! Follow on Twitter @TetZoo.

The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. JAHeadden 8:57 am 11/20/2012

    Nice update. I would like to add these more recent discussions on the topic, though tangential to the main topic (trunks), they relate to updates to much of the data presented therein: Whitlock on microwear and snout-shape to feeding behavior; and Young et al. on biomechanical modeling in Diplodocus longus, with tacit support for precision biting and “unilateral” branch stripping.

    Whitlock, J. A. 2011. Inferences of diplodocoid (Sauropoda: Dinosauria) feeding behavior from snout shape and microwear analysis. PLoS One 6:e18304 DOI:/10.1371/journal.pone.0018304
    Young, M. T., Rayfield, E. J., Holliday, C. M., Witmer, L. M., Button, D. J., Upchurch, P. & Barrett, P. M. 2012. Cranial biomechanics of Diplodocus (Dinosauria, Sauropoda): Testing hypotheses of feeding behaviour in an extinct megaherbivore. Naturwissenschaften 99:637-643.

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  2. 2. vdinets 9:41 am 11/20/2012

    Still, the shape of Brachyosaurus skull clearly suggests that there was something interesting on top of the frontal part of the skull. A resonator of some kind, perhaps?

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  3. 3. kilianh 11:27 am 11/20/2012

    “given that the whole point of a trunk is that it, rather than the jaws, is used to pluck vegetation” – given that you mention dik-diks as having trunks, that doesn’t seem the only point of a trunk?

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  4. 4. Andreas Johansson 2:20 pm 11/20/2012

    * And, yes, I’m fully aware of the controversy over deinothere trunk and facial anatomy.

    Well, I’m not. Spill the beans, plz!

    On the subject of illustration, unless memory is playing tricks on me, one of my dad’s old (probably bought in the eighties) dino books had a little picture of the head of a hypothetical trunked brachiosaur.

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  5. 5. Jerzy v. 3.0. 3:45 pm 11/20/2012

    Why crampon-using dromaeosaurs are unlikely, besides that Jurassic Park-like vision of supercharged predators is cooler?

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  6. 6. naishd 3:54 pm 11/20/2012

    Thanks for comments so far. Much to respond to.

    Vlad (comment 2): yes, I think it’s plausible that there may have been unusual soft-tissue structures – perhaps involving erectile or inflatable tissue – associated with the fleshy nostril, as suggested by that obvious rim and concave bowl-like area on the snout. A possible role in modifying noises is plausible. Having said that, we might guess that sauropods used their gigantic windpipes and air-sac system as resonators or amplifiers for whatever vocalisations they made. As always, this is stuff we want to know about, yet it remains unknowable due to an absence of the right sort if anatomical information.

    Darren

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  7. 7. Heteromeles 4:25 pm 11/20/2012

    Oh, you’re no fun. With that endocast evidence, no one can even argue that male sauropods had erectile noses for sexual display even. Harrumph!

    Nice work otherwise. Good to see it updated.

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  8. 8. naishd 4:36 pm 11/20/2012

    kilianh (comment 3) says…

    “given that you mention dik-diks as having trunks, that doesn’t seem the only point of a trunk?”

    You’ve highlighted an important point that I meant to clarify in this updated version, and yet forgot to. It’s that there is more than one kind of ‘proboscis’. Elephants and tapirs have a highly flexible proboscis that can be curled ventrally into the mouth – a sort of proboscis that is prehensile, and can function as a feeding tool. But dik-diks, sengis, softshell turtles and some other animals have a proboscis that, while sometimes very mobile at its tip, is not prehensile and (so far as I know) cannot reach the mouth and is not used as a feeding tool. These organs variously improve the animals’ ability to sniff out prey in leaf litter (sengis), to thermoregulate (dik-dik), or are used as snorkels (softshell and matamata turtles).

    I had this in mind, and I think it’s why I started to refer to ‘proboscides’ rather than ‘trunks’ in parts of the article. When we come to sauropods, it doesn’t make too much difference, since the evidence says ‘no’ to a proboscis of any sort. However, when they have have imagined as trunk-/proboscis-bearing, they’ve been imagined with mobile, prehensile, elephant-like trunks, not the shorter, non-prehensile organs of the sort seen in dik-diks and so on. Maybe I should modify the article to clarify all of this. Thanks for bringing it up.

    Darren

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  9. 9. naishd 5:14 pm 11/20/2012

    Finally (for now), Jerzy asked (comment 5)…

    “Why crampon-using dromaeosaurs are unlikely, besides that Jurassic Park-like vision of supercharged predators is cooler?”

    It’s nothing to do with what’s cool. The ‘crampon’ idea proposes that dromaeosaurs used their enlarged digit II claws to climb up the bodies of their prey to use their jaws as the primary weapons. I don’t necessarily think that use of the digit II claw as a climbing tool is all that bad (more on this real soon, once a certain in-press PLoS ONE paper is out), but I just can’t help but find the idea that they climbed the bodies of their prey when attacking them as fairly silly.

    It seems more likely to me, given what living animals do, that (1) they didn’t tackle prey many times their own size, and instead predated animals similar in size, or smaller, than they were, or (2) they deliberately attacked especially vulnerable, thin-skinned parts of the body, like the side of the belly near the thigh, or the neck. Since I wrote the article above, Denver Fowler and colleagues have of course argued that the hypertrophied digit II claws of dromaeosaurs were functionally similar to those of modern accipitrid raptors: that is, they were used in prey restraint rather than in piercing or tearing at tissue.

    Darren

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  10. 10. Heteromeles 8:12 pm 11/20/2012

    In point of fact, one could test the feasibility of the Dromaeosaur “crampon” using existing technology, if a human can be seen as a crude analog of a Dromaeosaur.

    What you do is, a) buy a couple of these plastic karambits (http://www.coldsteel.com/Product/92FK/FGX_KARAMBIT.aspx), create a suitable dinosaur prey analog (an old couch? a shipping pallet wrapped in burlap? a dead elephant?), attach these karambits to a pair of appropriately-shaped boots (ask your local maker contingent to help out), and finally, see what happens when your designated stuntman/Dromaeosaur analog puts significant weight on plastic karambit blade toes and tries to climb or cling with them.

    This proposal is only partially tongue in cheek.

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  11. 11. David Marjanović 11:48 pm 11/20/2012

    I’d expect a climbing tool to not be flattened from side to side.

    Incidentally, I should note here that members of at least one sauropod lineage (Dicraeosauridae) evolved short necks.

    Short only by sauropod or elasmosaur standards.

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  12. 12. Dartian 3:14 am 11/21/2012

    Darren:
    [Coombs] noted that “There is certain reluctance to accept a sauropod fitted with a proboscis because no living reptile has anything comparable to an elephantine or tapiroid nose”

    There are, at least, those various freshwater turtles equipped with ‘snorkels’ that you mention in comment #8. Did Coombs simply forget about them?

    hypertrophied necks of sauropods seem to have played the same role that trunks do in the mammals that have them, and it really seems like overkill for both structures to have been present in tandem

    I’m not so sure that this is necessarily the case. Consider the giraffe. It has a hugely long neck (by mammalian standards) but it also has a long, mobile and prehensile tongue which it uses for grabbing foliage. This suggests that even though the giraffe’s neck is long, in foraging a little extra length wouldn’t, and doesn’t, hurt. (The giraffe’s skull is probably relatively so small that there is no room for all the musculature needed to evolve a long trunk; the tongue probably does a better job in this regard.)

    Speaking of tongues, can we make any reasonable inferences about sauropod tongue morphology? Is the idea of a sauropod possessing a giraffe-like (or even a chameleon-like!) prehensile tongue too outlandish?

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  13. 13. naishd 7:04 am 11/21/2012

    Dartian: good points. Sure, giraffes have flexible tongues and lips, so do long-necked camels and so on. But they don’t have trunks. As for sauropod tongues, the reasonably large hyoids known for several genera have led some people to suggest that their tongues were big and muscular, but we can’t say much more than that.

    By the way, not ignoring your emails – just cannot even begin to deal with email backlog. Things will ease up once lecturing season finishes at end of the month.

    Darren

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  14. 14. Dartian 11:37 am 11/21/2012

    By the way, not ignoring your emails

    No prob. I guessed that your workload was at its usual level. Although, for a moment I did wonder if you were miffed by my party-pooping in the recent eagle comments thread. ;)

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  15. 15. naishd 11:51 am 11/21/2012

    Dartian, you mean attempt at party-pooping. You’re completely wrong about those eagles :) I should follow this up with a full-fledged article on eagles vs primates at some stage.

    Darren

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  16. 16. Yodelling Cyclist 12:39 pm 11/21/2012

    “I’d expect a climbing tool not to be flattened side to side”.

    Ice axes? Really, you would: surely the climbing implement has to be flattened in one dimension (in order to geenrate the pressure to penetrate a hard substrate) then requires the thickness in the vertical dimension to prevent deformation and cracking as weight is applied vertically. Hence: ice axe.

    IIRC the BBC did a documentary called “The Truth About Killer Dinosaurs” in which an anamatronic rig was built to “kick” a steel reproduction of a Deinonychus claw into pig carcasses. The finding was that whilst penetration was facile, the claw shape casued the flesh to ruck up under the claw as it slashed downwards, and jammed the slashing movement. The interpretation put forward in the documentary was that this was proof that the animals were not kicking and slashing, but I’ve always wondered: if the cutting movement is jammed, doesn’t that mean the predator could use the claw for support,i.e. to climb?

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  17. 17. Heteromeles 1:13 pm 11/21/2012

    I’d also point out that Cold Steel sells a steel karambit, or used to? Since I bought one of their plastic knives out of curiosity, I can say conclusively that:
    a) plastic ain’t steel, and a plastic knife doesn’t cut like a steel knife of the same shape (the best word for their cutting performance is hilarity. I recommend experimenting while drinking beer. Note that cutting and piercing are two different functions, and I advise sobriety while testing the tip).
    b) the plastic they use seems a lot more like horn, although that’s just from handling it, not doing a breakage test.

    Now I agree with David to some degree: a knife blade isn’t the same as a claw. However, YC is right: climbing claws aren’t round either (and yes, I have a climbing axe. A very flat climbing axe). The karambit design was based on a tiger’s claw originally, and cats climb just fine with their claws.

    The basic point is that if you’re cringing at the thought of hanging your weight off a couple of plastic karambits on a hadrosaur analog, your instincts may be telling you something. If the thought intrigues you, take appropriate safety precautions, set up several video cameras, and go for it.

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  18. 18. Jerzy v. 3.0. 8:30 pm 11/21/2012

    Ah, I understood “crampon-using dromaeosaurs” in the usual sense of crampons. That is, is there any evidence against that (many) dromaeosaurs used their inner claws for climbing trees?

    I agree that dromaeosaurs climbing large prey are very unlikely.

    Dromaeosaur feet lacked opposable toes and grasping ability, so I don’t understand how they would hold small prey? Weren’t also dromaeosaur leg joints much less mobile than feet of many tree-perching birds?

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  19. 19. Tayo Bethel 10:34 pm 11/21/2012

    I’ve read the article on dromaeosaurids possibly using their feet to restrain prey–it sounds very plausible. Still, I did wonder how the feet of dromaeosaurids could grasp prey. Maybe with assistance from the hands?

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  20. 20. Dartian 3:32 am 11/22/2012

    Darren:
    I should follow this up with a full-fledged article on eagles vs primates at some stage.

    Bring it on, bird man! ;) But you should watch this video beforehand (there is no eagle there, but an owl will do).

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  21. 21. vdinets 10:29 am 11/22/2012

    Darren (#6): so, maybe the structure on top of the face was used to modify the sound produced in the body and neck? That would hint at the possibility of either complex songs, like those of humpbacks, or some form of language.

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  22. 22. David Marjanović 11:40 pm 11/22/2012

    Ice axes? Really, you would: surely the climbing implement has to be flattened in one dimension (in order to geenrate the pressure to penetrate a hard substrate) then requires the thickness in the vertical dimension to prevent deformation and cracking as weight is applied vertically. Hence: ice axe.

    …OK, but dromaeosaur sickle claws are quite thin on the supposedly weight-bearing side. I wonder if the keratin sheath actually had a cutting edge.

    IIRC the BBC did a documentary called “The Truth About Killer Dinosaurs” in which an anamatronic rig was built to “kick” a steel reproduction of a Deinonychus claw into pig carcasses. The finding was that whilst penetration was facile, the claw shape casued the flesh to ruck up under the claw as it slashed downwards, and jammed the slashing movement.

    That test was quite unsatisfying, because it completely separated kicking and slashing and didn’t test what would happen if both were done in one smooth movement. They stuck the claw straight in, made a pause, and then rotated it. Also, they used the shape of the bony ungual; they should have tried a few options for what the keratin sheath could have been like…

    Dromaeosaur feet lacked opposable toes and grasping ability, so I don’t understand how they would hold small prey?

    Read the Fowler et al. paper. It’s in PLoS ONE, which means access is free.

    Weren’t also dromaeosaur leg joints much less mobile than feet of many tree-perching birds?

    ~:-| Do perching birds have particularly mobile leg joints?

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  23. 23. Yodelling Cyclist 2:56 pm 11/23/2012

    I think the conclusion coming from the BBC tests is: climbing is possible, but slashing is not impossible. A motion was demonstrated which would permit the creature to climb, or at least achieve purchase with its foot claws. Effective slashing requires an unspecified other movement, and an undemonstrated keratin sheath which in life might be adapted to slashing (or indeed to climbing).

    Ultimately, I have no idea as to the answer to this, but just off the top of my head I have two thoughts to share: first is the arresting image of a dromaeosaur hooked into a large animal, biting away and kicking new footholds for itself while flapping away fit to bust to maintain balance, and second that any really large animal, in serious danger from such a threat from a lone predator, could just fall on its side and crush the attacker.

    As for sauropods: those necks are immense resonators. Those creatures might have been capable of staggering infrasound wavelengths over huge distances. With huge fleshy nose/lips over the top of the bone nostrils, on the other hand, there’s the potential for some impressive raspberry blowing…..

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  24. 24. Allen Hazen 4:46 pm 11/23/2012

    Question from the mammal enthusiast: how secure is the reconstruction of Macrauchenia? Does the skull show muscle-attachment scars, etc, that pretty definitely indicate the presence of a trunk, or is the usual reconstruction … speculative? South American tertiary mammals are weird and wonderful, but M. really does look like a fever dream!

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  25. 25. David Marjanović 6:02 pm 11/23/2012

    The skull of Macrauchenia always reminds me a lot of Diplodocus. It sort of doesn’t look mammalian.

    Of course, what may be throwing me off the most, other than the retracted nostrils, is the fact that there’s no diastema. The toothrows are continuous.

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  26. 26. Heteromeles 6:21 pm 11/23/2012

    Actually, my guess for any complex fleshy organ on the head of a sauropod would be a pressure lock of some sort. They’ve got fairly high air pressures building up in their neck, both in the trachea and in the air sacs of the neck, and that head’s presumably going up and down, meaning there’s some regulation of blood pressure happening too. I could easily see very muscular nostrils being necessary simply to help control the varying pressures as the head rose and fell.

    As for the dromaeosaurs’ sickle claw, the more I look at it, the more I wonder. Comparing dromaeosaur feet to those of ostriches (e.g. this image), the raptors’regular foot claws don’t look that different from those of an ostrich (not that they’re ever illustrated that way. Sharp claws always lampshade the predators), and it’s obvious that the sickle is being carried in that hyperextended pose to keep the tip off the ground.

    That said, how did they use the sickle claw? One dumbass assumption is that it was like a switchblade, stabbing down from the animal’s foot. That seems weird, unless there’s some huge muscle in the foot that’s not obvious. If they used the sickle claw when the toe was straight and locked, then the sickle would have protruded from the bottom of the foot, which does indeed suggest that they used it for killing. It’s also, and very obviously, an awkward angle, unless you’re jumping on the sickle point, or doing some sort of cling-and-disembowel movement, such as a cat might do. It’s worth noting that cassowaries do just fine attacking with their straight claws, and ostriches kick quite well too, so I’m discounting the straight kick for now.

    Another human analog for the sickle toes is as tree-climbing spurs (cf: this image). Since animals up to the size of black bears climb hanging on claws, I’d suggest it’s a possible use, especially for the smaller species.

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  27. 27. Andreas Johansson 3:19 am 11/24/2012

    any really large animal, in serious danger from such a threat from a lone predator, could just fall on its side and crush the attacker.

    The laws of Mesozoic illustration surely mandate that deinonychosaurs attack in packs.

    More seriously, would falling on one’s side be a good idea if one’s a multi-tonne ornithopod or multi-decatonne sauropod? Would the ribs, lungs and whatnot survive hitting the ground at appreciable speed?

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  28. 28. David Marjanović 5:27 pm 11/24/2012

    They’ve got fairly high air pressures building up in their neck

    …Please explain.

    That said, how did they use the sickle claw? One dumbass assumption is that it was like a switchblade, stabbing down from the animal’s foot. That seems weird, unless there’s some huge muscle in the foot that’s not obvious.

    Well, there’s that huge muscle attachment site on the flexor tubercle that Achillobator is named after (it isn’t named after Achilles, it’s named after the Achilles tendon). Toe flexors (and extensors) are in the lower leg, not in the foot.

    Another human analog for the sickle toes is as tree-climbing spurs (cf: this image). Since animals up to the size of black bears climb hanging on claws, I’d suggest it’s a possible use, especially for the smaller species.

    But why would only one claw be enlarged this way? The only extant analogues for the claw on II being much larger than those on III and IV are raptors (fittingly enough *groan*), though their first claws are larger still.

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  29. 29. Heteromeles 5:50 pm 11/24/2012

    @David, if you have to keep blood pressure high in the brain of a sauropod, one of the simplest ways to do this is to pressurize the airways up and down the neck. It’s similar to the anti-GLOC procedures that jet fighter pilots use to keep from blacking out at high-gees, where they use pressurized breath holding and muscle contractions to keep blood from pooling in their legs. The problem with using pneumatic pressure in the neck is that you need a pretty sturdy pressure valve somewhere to make it work, both as the head is rising and dropping. I’m suggesting that maybe the space on some sauropod’s head held the muscles for such a valve (this also assumes that the trachea and esophagus were separated in sauropods). This could pretty readily be disproved, if some very long-necked sauropod had tiny little nares with no space for muscular valves.

    As for tree climbing with a sickle claw, if you didn’t go look at the tree-climbing spurs, go look at them. They sit on the human instep, so that the weight of the climber drives the sharp point into the wood. Since the sickle on a dromaeosaur sits in about the same relative position, I’m speculating that they could have used the sickle claw to climb by standing on the claws. It’s a good use, in that the weight of the climbing animal would drive the claw into the wood, and they could pull out simply by ascending. This contrasts with the way bears and tigers climb trees, where they hang off of their claws. In the later case, more claws are better, because one or more could fail.

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  30. 30. Jerzy v. 3.0. 9:07 am 11/25/2012

    @27
    “More seriously, would falling on one’s side be a good idea if one’s a multi-tonne ornithopod or multi-decatonne sauropod? ”
    If footage of lions hunting elephants and hippos is an example: 1) large herbivore can drop small pursuers simply by running and shaking. 2) major challenge is biting through the thick layer of skin and fat. That would be very difficult for a relatively weak-jawed deinonychosaurs.

    Incidentally, nobody seems to speculate over how thick was skin of extinct animals.

    @28
    “But why would only one claw be enlarged this way?”
    Other toes were used for running. There is no good living example of a flightless biped which climbs trees – besides humans with crampons.

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  31. 31. Heteromeles 10:56 am 11/25/2012

    “But why would only one claw be enlarged this way?”
    Other toes were used for running. There is no good living example of a flightless biped which climbs trees – besides humans with crampons.
    .

    How about Kakapos? Still, I agree with your point, that humans are the most common flightless bipedal tree climbers. The one change I’d suggest is that I don’t think tree climbers use crampons, which are for ice and snow. They use the spurs or other gadgets.

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  32. 32. naishd 11:30 am 11/25/2012

    Jerzy (comment 30) says…

    “Incidentally, nobody seems to speculate over how thick was skin of extinct animals.”

    Jerzy, you always says these things as if you’re incredibly knowledgeable of the entire literature. People have OFTEN speculated on the skin of extinct animals; the problem is lack of data, as it always is with these things.

    “There is no good living example of a flightless biped which climbs trees”

    Tree kangaroos and frilled lizards are facultative bipeds that do a lot of tree climbing, and of course they use their forelimbs when clinging and climbing vertically. Therein lies the analogy with dromaeosaurs and so on, since it can be assumed that they also used their clawed hands when climbing.

    Perhaps the big problem with the imagining of scansoriality in non-avialan theropods is that no living animals are close analogues of their body shape – I mean, they’re like birds, but different from living birds in having far more prominent, (apparently) far more useful clawed hands. If, then, you imagine a hypothetical flightless corvid, crow or owl with big, medially facing clawed hands, are you seriously incapable of imagining how it could use it hands and feet to climb a tree? (this is meant to be stated in rhetorical fashion, and not posed at anyone in particular). I and colleagues have a paper coming out in a few days on the issue of climbing in Mesozoic birds and other maniraptorans. See if you can predict what our conclusions are…

    Darren

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  33. 33. accipiter 12:42 pm 11/25/2012

    just a little delayed side note on the crampon-use for climbing on prey in maniraptors: when modern raptors wrestle large prey, they can use their foots exactly like climbing boots, to work their way to the head or neck one foot at a time and grasp the prey there, so the idea is not completely ridiculous or without any modern equivalence:
    look at this extremely impressive video of captive Gyrflacon on a Canada goose: ESPECIALLY AT THE 3:55min MARK

    http://www.youtube.com/watch?v=UkW7r-rgeBQ&feature=related

    however i agree that i don’t see deinonychosaurs do this to very large prey Rodeo style as they have only one large claw, wich means laking an Opposable Pincer they whould be shaken off easily.
    BUT, if a falcon can wrestle to the ground a prey so larger than himslef, then a deinonychosaur could do it even more easily as they have help of hands and jaws in addition… so while they probably didn’t hitch ride on large hadrosaurs or anything like that, they MAY very well have been capable of routinely wrestleing quite heavier and larger than themselves to the ground and kill them slowly like this.

    and just a stupid idea: when you see birds running, fighting (or doing anything other than walking in general) on the ground, they always use their wings for something: extra speed and acceleration, propelled jumps, extra balance, and extra control when running (using wings like airbreaks on one side to fast-turn for example: look at ostriches).
    so i’m wondering has anyone looked at how non-avian theropods might have done exactly the same?? at least deinonychosaurs had very long remiges on arms making almost bird-sized wings, long feathered tails with rectrices, and EVEN LEG-WINGS like microraptor for most of them apparently…

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  34. 34. David Marjanović 1:48 pm 11/25/2012

    This could pretty readily be disproved, if some very long-necked sauropod had tiny little nares with no space for muscular valves.

    How about Diplodocus and Barosaurus?

    so i’m wondering has anyone looked at how non-avian theropods might have done exactly the same??

    That’s very common in the literature.

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  35. 35. Heteromeles 2:20 pm 11/25/2012

    This could pretty readily be disproved, if some very long-necked sauropod had tiny little nares with no space for muscular valves.

    How about Diplodocus and Barosaurus?

    Good point. They still have those absurdly high-placed nares though. One suspects that they were strongly visual animals, because there isn’t much room for a well- developed olfactory center in there.

    Incidentally, does anyone have a good picture of the nares of either of these sauropods, especially showing the nares? Looking at an Apatosaurus skull, there appears to be some room for a pressure-valve type nostril there.

    This is highly speculative, of course, because the best analog we have for a pressure-valve nares isn’t a nose at all, but the sphincter ani muscles, and they don’t need a huge set of bones to anchor them, come to think of it.

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  36. 36. Heteromeles 2:27 pm 11/25/2012

    …And if you’re saying to yourself, “what a minute, did he just call sauropods, the most glorious animals evolution has ever produced, a bunch of buttheads?”…

    Yes, yes I did. Sometimes, that’s what it takes to make it big on this depraved planet we call home.

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  37. 37. Yodelling Cyclist 10:06 am 11/26/2012

    Perhaps I’m just being slow, but I don’t see how pressure locks in the neck help a sauropod keep blood in its brain. In humans, anti-GLOC procedures don’t so much go for breath holding (it occurrs as a consequence of the procedure) as squeezing as many muscles below the heart as possible, raising the blood pressure and helping keep blood in the brain. It’s not a long term solution: blood circulation through the brain and head in general is impaired, but I guess sauropods could just adapt somehow. Pressurising the neck (above the heart), constricting the blood vessels in the neck through applied air pressure is just going to restrict blood flow more. Thinking about this maybe it’s just a pump problem.

    When you force fluid through a tube you require a pressure differential, smaller the tube diameter, the larger the required pressure differrential for a required flow rate. If you don’t believe me, pinch your nose and breathe through a drinking straw. If there is a bend in the tube, the pressure requirement goes up rapidly with the radius of curvature of the bend. I have no idea how rapidly sauropods would be breathing, or the theoretical diameter of a sauropod trachea (David, Darren, any help here?) but given how long the straw is and the fact that they must have been shifting a lot of gas when the breathe, possibly they just had nothing over their nostrils: just the straightest possible tube to facilitate breathing.

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  38. 38. Heteromeles 11:57 am 11/26/2012

    The issue, as I understand it, is the variable blood pressure differential in sauropod brains. They have to be able to go from head below heart (when they’re drinking) to head fully elevating many meters above the heart (if feeding fully erect). While it’s easy to engineer a solution for either of these extremes, going from one to the other is hard. When the head’s high, structures like one-way valves in the arteries (which I believe giraffes have) along with thick artery walls and a big heart can help pump blood that high. Unfortunately, such structures could rupture the vessels in a sauropod’s head when it drops, unless there’s a way of drastically reducing the pressure.

    I’m proposing that sauropods used air pressure (in the air sacs in their necks) as a variable pressure mechanism. When pressures inside the blood vessels are high, air pressure on the outside would keep them from breaking and hemorrhaging. When blood pressures were low, releasing the air pressure would keep the vessels from squeezing shut. To adjust air pressure, you need a valve somewhere, and I’d suggest nostrils for that.

    Obviously, neck air sacs were also there reduce neck weight. Thing is, I just keep thinking about how simple breath locking can put pressure in someone’s head. My personal experience was with “iron shirt chi kung” breathing (basically, pressurizing your abdomen using lung air pressure, so that something hitting it will cause it everything to move together, rather than the impact causing a shearing shock wave). Done wrong (as I did), you end up with a nasty head ache and high blood pressure.

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  39. 39. Jerzy v. 3.0. 4:06 pm 11/26/2012

    @33
    Good video. One can see also how much falcon legs move in all directions, including to the sides, as the goose jumps around (eg. 1.37-1.45 or 2.11). Were deinonychosaur legs capable of such motion?

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  40. 40. Yodelling Cyclist 4:33 pm 11/26/2012

    Ah, so the pressure valve is for when the head is down and the sauropod must squeeze the blood vessels to prevent excessive blood pressure popping vessels in the brain…hmm I had misunderstood. Still don’t buy it, but it’s an interesting idea ;-) .

    Since this whole article was about….outlandish hypotheses, what about a pneumatic or hydraulic nostril that could be inflated and connected to the lymphatic system in such a way as to give a low resistance (relatively low resistance) path way to earth? I’m thinking of a lightening rod, because surely sauropods got hit by a fair amount of lightening…

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  41. 41. Jerzy v. 3.0. 5:28 pm 11/26/2012

    @32
    “Jerzy, you always says these things as if you’re incredibly knowledgeable of the entire literature”

    Because it makes people think. ;) In any case, I came across several situations when I think the thickness of the skin of extinct animals was underestimated. One are “shrink-wrapping” reconstructions which you also don’t like.

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  42. 42. Heteromeles 5:46 pm 11/26/2012

    Have to disagree on the lightning hypothesis. Extant conifers like redwoods have grow *rapidly,* which can be seen as an adaptation to grow out of the sauropod browsing zone ASAP. They also are excellent root sprouters, which may be another adaptation to surviving browsing.

    In any case, even in crappy habitats, cupressoid conifers can get 50-100 feet or more tall, and that makes them the highest points in the local environment.

    Besides, given how much methane the sauropods undoubtedly generated, it would be far better not to have a spark anywhere near them, on the inside or out. Those hollow bones would make excellent shrapnel.

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  43. 43. Jerzy v. 3.0. 7:52 am 11/27/2012

    @42
    “Besides, given how much methane the sauropods undoubtedly generated, it would be far better not to have a spark anywhere near them, on the inside or out.”

    Maybe overlooked anti-predator strategy? Imagine giant bombardier beetle analogues… ;)

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  44. 44. Heteromeles 8:08 pm 11/27/2012

    @Jerzy, not fumigators? Being around the back-end of a sauropod couldn’t have been that pleasant. Maybe that’s why they held their heads so high, and had such (apparently) poorly developed olfactory capabilities. Yeah.

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  45. 45. David Marjanović 9:09 pm 11/27/2012

    I have no idea how rapidly sauropods would be breathing, or the theoretical diameter of a sauropod trachea (David, Darren, any help here?)

    No quantifiable idea. Just saying that they must have breathed a lot less often than a hypothetical mammal the same size; that’s what’s true for birds today.

    Flow speed, IIRC, through a tube increases with the fourth power of its diameter.

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  46. 46. Jurassosaurus 10:47 pm 11/27/2012

    One suspects that they were strongly visual animals, because there isn’t much room for a well- developed olfactory center in there.

    Not necessarily. Witmer et al. (2008) have looked at the endocasts of a variety of sauropods including Diplodocus, and Camarasaurus. In at least these two taxa the olfactory bulbs were fairly substantial. They probably weren’t walking noses, but even Diplodocus with its relatively small olfactory chamber, still had the potential to detect and discriminate fine odors.

    Flow speed, IIRC, through a tube increases with the fourth power of its diameter.

    Resistance increases by the 4th power of diameter. Flow speed changes (inversely) with the square of the diameter. Hugh-Jones (1978) used this reasoning to explain the abnormally slow breathing that they documented in giraffes (which have smaller, more resistant, tracheae than predicted for a mammal their size).

    Of course all of these are meant to apply to nice circular tubes. Once one moves away from circles the math has to get more, er, creative. :)

    Refs

    Hugh-Jones, P., Barter, C.E., Hime, J.M., Rusbridge, M.M. 1978. Dead Space and Tidal Volume of the Giraffe Compared with Some Other Mammals. Resp.Phys. Vol.35:53-58

    Witmer, L. M., R. C. Ridgely, D. L. Dufeau, and M. C. Semones. 2008. “Using CT to peer into the past: 3D visualization of the brain and ear regions of birds, crocodiles, and nonavian dinosaurs.” in Endo, H. and Frey, R. (eds.), Anatomical Imaging: Towards a New Morphology. Springer-Verlag, Tokyo. pps:67–88

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  47. 47. Andreas Johansson 12:03 pm 11/29/2012

    Flow speed changes (inversely) with the square of the diameter.

    Assuming a constant volume flow, that is. Wouldn’t the relationship at a constant pressure difference be more relevant to determine an animal’s breathing prowess?

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  48. 48. Yodelling Cyclist 1:36 pm 11/29/2012

    For a crude estimate, to start we need to know how much gas (volume at specified pressure, or mass, which I would prefer) these animals needed to exchange per unit time, neck length and windpipe diameter.

    From that, a required pressure differential can be extracted, and possibly something could be said about the muscle masses required to achieve that pressure (although that would require far more knowledge about muscle and general anatomy than I have, I’m a physical chemist by training and occupation). We could also try putting some crude kinks in the pipe – sorry, neck – and see what that does to the required pressures. I might be able to get (again, wildly guess with numbers) the energy requirement for breathing. Certainly raising the neck would make it harder to breathe – pumping “round a corner” is always said to roughly halve the pumping speed (when we are just doing order of magnitude calculations), so raising that neck will have made breathing a surprising challenge.

    Very crude estimates, I should say.

    Link to this
  49. 49. cephalopodomorphist 7:11 am 09/9/2014

    So could this kind of thing work:
    http://cephalopodomorphist.deviantart.com/art/Spiral-Balloon-Brachiosaurus-481262004
    I did it after reading this article. Very interresting! Great job.

    Link to this

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