Jurassic World and the case of the droopy-tailed Stegosaurus

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As I write this the US premiere of Jurassic World is just around the corner. I had gone back and forth regarding this post given that we currently know very little about the film and as such the interpretations written about here and elsewhere may well be pointless by the time the film premieres.

Ultimately I decided to post this anyway since the overall thrust of the article should remain true regardless of how the film pans out.


Now there has been a lot of buzz around Jurassic World since it was first announced last year. The buzz has been mixed, but fairly positive. I suspect this was, in part, because everyone was happy to hear that the godawful military dinosaur idea was shelved in favour of a more “traditional” JP franchise storyline. Nonetheless the movie has still drawn its fair share of detractors, including myself. Most of the people who are unhappy with the film are either paleontologists, or hardcore dinophiles. Many of the problems leveled at the film have to do with the portrayal of the extinct animals. The problems are actually myriad ranging from pterosaurs capable of picking up humans using grasping feet, mosasaurs that are twice the size of blue whales, sauropods covered in elephant skin rather than scales (a problem not unique to Jurassic World), everything about Velociraptor, and of course Indominus rex.  My biggest beef with the film is that the dinosaurs are not being shown as dinosaurs so much as monsters. However, after The Lost World: Jurassic Park came out it became pretty evident that Spielberg’s original vision of portraying dinosaurs as animals had been shelved in favour of the more entertainment-friendly movie monster approach. However, for what seems like a majority of the detractors, the biggest gripe with the film has to do with a lack of  feathers on pretty much all the dinosaurs. This seems to be a common theme these days with a particularly vocal group of dinophiles and paleontologists strongly pushing for the feathering of every dinosaur in sight and insisting that all media that portrays scaly (erroneously called: “naked”) dinosaurs is inaccurate. Never mind the fact that a feathered, pack-hunting, 2 meter tall Velociraptor mongoliensis is still every bit as inaccurate as a scaly one.

Anyway, I digress. Dealing with the overwhelming amount of internet drama surrounding Jurassic World (and the media depiction of dinosaurs in general) is a topic for another day. My reason for writing this post is centered around one particular criticism that popped up a few weeks ago.

The scene that sparked overblown internet outrage.
The scene that sparked overblown internet outrage.

 

The scene in question is shown above. It is a still from the Jurassic World TV spot linked above. It features a variety of herbivorous dinosaurs wandering around the park as visitors shoot by on motorized hamster balls. It is a very short scene that lasts about two seconds before moving on, yet in that time frame so many dinophiles became outraged.

Why? Well, as one can plainly see in the image, that Stegosaurus is dragging its tail. This is obviously a throwback to the Victorian era version of dinosaurs as sluggish, cold-blooded animals. It’s a sign that the filmmakers cared more about nostalgia than accuracy, etc.

Stegosaurus in The Lost World: Jurassic Park (top) and in Jurassic World (bottom).
Stegosaurus in The Lost World: Jurassic Park (top) and in Jurassic World (bottom).

Remember, this was from a two second scene featured in a TV spot. Still, with even that little bit of information it’s apparent that this Stegosaurus is not dragging its tail. The animal is walking in tall grass. One can see that its feet are lower than its tail. In fact in the scene one can see the tail freely swinging back and forth. So no, this is not evidence of tail-dragging Victorian throwbacks.

What about the droop, though?

The droop is a more interesting question. The Stegosaurus in Jurassic World definitely has its tail lower to the ground than its previous incarnation (in The Lost World: Jurassic Park). Is the droopy tail a sign that the creators of Jurassic World were using outdated information for their dinosaur reconstructions?

The way I see it there are three possible scenarios for the droopy tail.

  1.  The filmmakers cared more about nostalgia than accuracy and used an older version of Stegosaurus.
  2. Wu and his team genetically engineered “slower” dinosaurs to appeal to the older crowd and better emulate the public’s perception of dinosaurs.
  3. This particular Stegosaurus happened to have its tail low to the ground, and it’s simply a sign of anatomical and behavioural variation in the living animal.

I think option one can be thrown out. It’s possible that the droopy tail was made as an homage to the pre-Dinosaur Renaissance dinosaurs, but nothing else in the film suggests that would be true. Further, given the precedent set in The Lost World: Jurassic Park, it seems unlikely that Trevorrow would do this, or that it would be greenlit by Spielberg.

Option two has precedence in the canon as Wu explicitly states in Jurassic Park the book:

“Why not push ahead to make exactly the kind of dinosaur that we’d like to see? One that is more acceptable to visitors, and one that is easier for us to handle? A slower, more docile version for our park?”

Hammond frowned. “But then the dinosaurs wouldn’t be real.”

“But they’re not real now,” Wu said. “That’s what I’m trying to tell you. There isn’t any reality here.”

So it’s possible that the Stegosaurus shown in the scene above is actually representative of the “slower, more docile version” of the park. Unfortunately, if that is true, then it would mean the filmmakers are aiding in perpetuating the myth that cold-blooded animals are slow.

However, I suspect that it is the third option that is the most likely. The reason for that can be seen both later in the original TV spot (19 seconds in) where we see a Stegosaurus walking with a higher-raised tail, and in the original trailer for the film, which showed another Stegosaurus with its tail held to nearly the same height seen in The Lost World: Jurassic Park.  That all three tail heights are seen in the same film strongly suggests that we are simply seeing behavioural variation, not a return to Victorian ideals of dinosaurs.

Stegosaurus from the original Jurassic world trailer (left) and one of the more recent TV spots (center and right)
Tail heights of Stegosaurus from the original Jurassic world trailer (left) and one of the more recent TV spots (center and right)

 

All of these interpretations, however, beg the question of whether these tail positions were anatomically possible. For that we need to go back a bit into the history of Stegosaurus and its reconstructions.

First discovered by Marsh (1877), Stegosaurus has had a long and sordid history in paleontology. Much of the controversy surrounding the animal had to do with plate arrangement (flat/vertical, one row/two rows, staggered/linear, dynamic/static, etc.), and brains. The infamous cliche about dinosaurs having brains the size of a walnut can be attributed to Stegosaurus. The controversy about brains stems from a sacral expansion of the neural canal that was once thought to house accessory ganglia referred to as a “second brain”. Tail controversies are much less common for Stegosaurus, with tail spike number and orientation being the biggest issues (Carpenter 1998, Carpenter & Galton 2001). Tail orientation itself has rarely come up.

Early restorations, notably Marsh (1891) and Lull (1910) featured a “tail dragging” version of Stegosaurus. I put tail dragging in quotation marks because for both mounts the tail is shown higher off the ground than the feet. Nonetheless one can assume that Marsh and Lull had intended to show the animal as a tail dragger, and indeed much of the fleshed-out reconstructions at the time reflected this (e.g., Charles Knight’s 1912 depiction, or Sir Ray Lankester’s 1905 depiction). Having the tail drag along the ground also influenced orientation of the tail spikes, resulting in most mounts showing the spikes running parallel to the vertebral spines. It’s worth noting that at no point were any of these reconstructions based on the anatomy of the animal. They appear to have just been chosen based on interpretations of dinosaurs at the time.

It’s not until  the late eighties—in particular 1986—that we first see the high-raised tail in Stegosaurus. Where? Robert Bakker’s infamous Dinosaur Heresies. As far as I can determine Bakker was the first person (or at least the first paleontologist) to depict Stegosaurus with a high-raised tail (feel free to correct me in the comments if you know of an earlier version). Bakker’s Heresies was in many ways the critical turning point for the Dinosaur Renaissance. With a new interest in portraying dinosaurs as highly active animals, post 1986 depictions of Stegosaurus largely showed the animal in that “Bakkeresque” pose with its tail shooting ramrod straight off the hips.

The funny thing is Bakker never offered any anatomical justification for his restoration. In fact there was no justification for this new positioning of the tail in Stegosaurus until 1998 when Ken Carpenter re-analyzed the skeleton of Stegosaurus. That means that every depiction of Stegosaurus with a high-raised tail prior to that moment was all conjectural. Note: that includes 1997’s The Lost World: Jurassic Park.

Original interpretations of Stegosaurus tail orientation (Marsh 1877). Dinosaur Renaissance interpretation (Bakker 1986).
Our changing view of Stegosaurus tail orientation. Right: Marsh 1891. Left: Bakker 1986. Note: The eight spikes for S. ungulatus are no longer thought to be valid.

 

So what did Carpenter find? In his 1998 paper, Ken Carpenter talked about tail position in relation to spike arrangement in Stegosaurus stenops. The reason for the reinterpretation came about during a remounting of the Denver Museum of Nature and Science’s Kessler Stegosaurus (DMNH 1438). Carpenter examined the connection between the terminal sacral vertebra and the first caudal vertebra (the sacrocaudal joint). He noticed that the caudal face of the centrum of the terminal sacral vertebra was deflected dorsally whereas the centrum of the first caudal was longer on its ventral side than its dorsal side. Taken together these results suggested that the base of the tail arced upward from the sacrum.  Carpenter pointed out that his reasoning followed Gilmore’s reasoning for reconstructing the tail of Diplodocus carnegii (Gilmore 1932). So from the base the first caudal vertebra was angled away from the plane of the sacrum. This orientation of the sacrocaudal joint is similar to what is observed in extant terrestrial lizards such as iguanas and varanids. In fact, when Gilmore (1932) was reinterpreting the tail in D. carnegii he made mention of this similarity.

The upward curvature of the tail in the sauropodous dinosaurs bears a striking resemblance to that of the large extant lizard Varanus komodoensis.

Dorsal deflection of the sacrocaudal joint in Varanus and Iguana. Left: First and second sacral vert (pelvis removed for clarity). Right: First (or more) caudal(s) showing dorsal deflection of the tail.
Left lateral views of sacral vertebrae showing dorsal deflection of the sacrocaudal joint in Varanus (OUVC 10689) and Iguana (OUVC 10446). Left: First and second sacrals (pelvis removed for clarity). Right: First (or more) caudal(s) showing dorsal deflection of the tail. Zygapophyses at 100% overlap.

Now that’s the base of the tail. What of the rest? Well, according to Carpenter (1998):

With the rest of the caudal vertebrae articulated so their centra faces are parallel, the tail is almost at the level of the sacrum throughout its length.

Carpenter placed the tail of Stegosaurus stenops in its osteological neutral pose (ONP). Much has been written about ONP in dinosaurs (Stevens and Parrish 1999, 2005; Taylor et al. 2009; Taylor 2014), but all of that has focused on the neck vertebrae of sauropods. One of the key questions that has come about from studies on ONP is how important it is to the animals themselves. In others words is the osteological neutral pose a pose that animals habitually keep their vertebrae in? Getting ONP in fossils can be difficult as taphonomic distortion can really screw up the alignment of the vertebrae, such as the zigzagging of the spinal cord that resulted from arranging the caudal vertebrae of Kentrosaurus aethiopicus in ONP (Mallison 2010). Orientation of the sacrum can have huge effects on interpretations of tail orientation based on ONP as Coombs (1995) showed for Euoplocephalus (downward deflected sacra of 30° result in tail dragging for ONP tails).

Judging from the vast array of posts from the SVPOW crowd, along with the aforementioned papers, it would seem that ONP may not mean as much as initial interpretations would have us believe. Further, given that tails don’t need to acquire food, nor do they act as a hub for all the senses in the body, we should expect to see even more freedom in movement for these structures.

Examples of the various tail positions available to extant reptiles. Dipsosaurus dorsalis standing, lying down, trotting, and running bipedally.
Dipsosaurus dorsalis showing the variety of tail positions available to extant reptiles. Clockwise from upper left: Standing and lying down images by Gary Nafis, trotting and running from Irschick and Jayne 1999 (figs 5B4 and 4B8)

Carpenter offered other evidence for a ramrod straight tail in Stegosaurus, including the presence of bifid neural spines (seen in the image below) and the length of plate bases over the tail. I’m not sure how useful the latter bit of evidence is as we don’t really have any animals alive today that have large, vertically projecting osteoderms jutting out of their backs. The plates in stegosaurs were embedded in the skin making it difficult to determine how well they should match up with the underlying vertebrae. The bifid neural spines would have provided extra areas of attachment for the m. transversospinalis, which are intrinsic back/tail muscles. They would have functioned in maintaining intervertebral integrity. Interspinous and supraspinous ligaments would have attached along the top of the neural spines as they do in extant amniotes (Tsuihiji 2004, Schwarz-Wings 2009). These ligaments have been associated with passive support for the vertebrae, and Carpenter argued similar for their function in keeping the tail held out straight. However, bifurcation of the neural spines seem more in line with expansion of the m. transversospinalis muscles (Wedel and Taylor 2013), which would not offer passive support. Increased muscle mass between the vertebrae, and a laterally offset intervertebral ligament system instead suggest that the tail was enhanced in favour of increased flexion, with the offset intervertebral ligaments acting as springs to bring the tail back in line after lateral flexion. This would aid in tail swinging, which Carpenter (1998) acknowledged could have been an alternative/complementary use of these structures.

The centra in Stegosaurus are amphiplatyan, which means both articular ends of the centrum are flat, or flattish surfaces. Humans have this same type of vertebrae too. On the outset they appear to be rather restrictive in their movements compared to the ball and socket arrangement seen in most reptilian vertebrae. Indeed, Gilmore (1914) even says as much for Stegosaurus:

…the caudal vertebrae are joined by closely fitting zygapophyses, which are present nearly to the distal end of the tail; moreover, the articular ends of the centra are rather abruptly truncated, not rounded or beveled, as in those animals having flexible tail. These structural details, combined with the series of plates along the dorsal side, must have made the tail of Stegosaurus a heavy, stiff appendage, incapable of more than cumbersome lateral movements and wholly unsuited for use on an active enemy.

Estimated 10th proximal caudal vertebra in lateral and rostral views. Modified from Gilmore 1914
Estimated 10th proximal caudal vertebra in S. ungulatus in lateral and rostral views. Modified from Gilmore 1914. prz = prezygapophysis, postz = postzygapophysis

Yeah, you read that right. Gilmore did not think that Stegosaurus did much to defend itself with its tail. New data since then have strongly suggested that Stegosaurus spikes were routinely used in defense (Carpenter 1998, Carpenter et al. 2005). Ah, but what of the seemingly stiff tail vertebrae? Recent work presented as last year’s Society of Vertebrate Paleontology meeting (Fronimos & Wilson 2014) suggest that the ball and socket arrangement may have evolved—counterintuitively—to better hold vertebrae together. Indeed, as the authors of that study pointed out in their alligator example the most flexible part of the crocodylian body (the tail) is actually composed of fairly flat-sided vertebrae in the last 2/3rds of the tail.

The centra in the tail of Stegosaurus are fairly short proximally, but gradually elongate towards the tip, a trait that is actually pretty common among reptiles. Keeping the vertebrae aligned with each other is simple enough as long as the prezygapophyses of one vertebra overlap the postzygapophyses of the previous vertebra. The amount of overlap provided by the zygapophyses gives us an idea of how much displacement can be put on each individual vertebra. As I mentioned above, Carpenter found that aligning all the vertebrae to their centra produced that ramrod straight tail. In contrast, Marsh and Lull kept the zygapophyses overlapping in their droopy tail reconstructions. So unlike the Bernissart Iguanodon—which had their tails broken to achieve the stance in their mounts (Norman 1980)—giving Stegosaurus a droopy tail does seem to be anatomically possible.

Okay, so it’s possible, but is it probable?

For that we need to look into the biomechanics of droopy vs. raised tails. As a reptile, the tail in Stegosaurus would have been a functional fifth limb. The muscles responsible for retracting the hind legs (m. caudofemoralis longus and brevis) attach to the proximal part of the tail. Like all muscles, the caudofemoralis muscle complex can only ever pull. To get maximum force and contraction from the muscle the distance between origin and insertion should be as straight as possible. The best way to achieve this is to hold that portion of the tail that houses the caudofemoralis complex as straight as possible. So how far did the m caudofemoralis longus stretch in Stegosaurus? In extant reptiles the m. caudofemoralis longus attaches to the underside of the transverse processes and the lateral faces of the haemal spines/chevrons (Persons & Currie 2011). The caudofemoralis complex eventually tapers off and terminates long prior to the end of the tail. Although not universal, one can use the point in which the transverse processes disappear (or descend from dorsolateral to lateral) as a starting proxy for the extent of the caudofemoralis (to be more exact we would need to look for evidence of the intermuscular septum scar on the chevrons, which is out of the scope of this blog post). For Stegosaurus this would suggest that the caudofemoralis complex extended for about the first 1/3rd of the tail. So for the most effective hind limb force production the first 1/3rd of the tail should be held straight. That still leaves 2/3rds of the tail free to droop if need be. Turning once more to the extant realm we see this type of tail extension during walking/trotting in most lizards such as the Komodo dragon in this video (2 minute mark).

Note how the tail does start to droop once the portion of the tail containing the caudofemoralis complex is gone. It was likely that Stegosaurus and other quadrupedal dinosaurs did similar things with their tails. The higher stance of dinosaurs compared to squamates would have resulted in the droopy parts of the tails rarely touching the ground, or maybe even lightly dragging. If they did lightly drag these marks would be unlikely to preserve, as data from extant Komodo dragon trackways have shown (Padian & Olsen 1984). Keeping the tail off the ground when moving is also useful for reducing drag force created by the friction between the resting tail and the ground. Willey et al. (2004) showed the effects of “tail braking” on locomotion in alligators. It would seem likely that many/most dinosaurs would have had their tails well off the ground when walking, or at least have the heaviest parts off the ground to reduce this tail braking effect. Again, behavioural studies of extant terrestrial reptiles seem to bear this out (e.g., Irschick and Jayne 1999).

So, biomechanically, there is a good reason for Stegosaurus to have held its tail straight. However, this reason is only valid during the parts of its life where it was moving its body from one area to the next (i.e., walking, trotting, running, tiptoeing through the tulips, etc.). If Stegosaurus was just standing around grazing there would be no biomechanical requirement for the tail to be held in the air. This holds true for most dinosaurs (theropods are the big exception since their tails were also acting as counterbalances to their torsos). It’s a thing that I think a lot of paleo art tends to gloss over. Animals that are just standing around are likely to pick the most energetically “cheap” body positions, and that probably meant tails that drooped on the ground. Once again we would be unlikely to see evidence of this in the fossil record since trackways almost always depict animals on the move where having a tail held high is important.

Just a friendly reminder. Tachymetabolic endothermy doesn't stop one from having a droopy tail.
Just a friendly reminder that droopy tails are pretty omnipresent among extant mammals too. Clockwise from left: mouse (stock photo), leopard (Mistvan), elephant (Yathin S. Krishnappa), horses (Dana Boomer)

So just to wrap things up:

  1. The Jurassic World promo material does not show a tail-dragging Stegosaurus
  2. Tail droop and occasional drag are not impossible anatomical positions for Stegosaurus
  3. As animals we should expect to see dinosaurs holding their tails in a variety of positions afforded to them by their anatomy

With all that in mind I will commend Jurassic World for showing off dinosaurs acting like animals (in at least some scenes). A separate scene in the trailer even showed a Triceratops lazily lounging about before getting up to move off. I think that these views of dinosaurs are useful as they remind us that these were not mythical monsters from a bygone age, but living animals that were doing more than screaming around the Mesozoic with their mouths open all the time.

~ Jura

As an aside for anyone interested, I suspect that Jurassic World will wind up as a fun splash in the pan summer blockbuster. It will have a sizeable opening weekend, coming in at number one at the box office, followed by a precipitous decline with each successive week. I predict that it will top out around $150–175M domestic gross. I would be genuinely surprised if it was able to crest over $200M. The days of the JP franchise being a huge moneymaker are long past us. [Editors note: Well colour me surprised.]

References

Bakker, R.T. 1986. The Dinosaur Heresies: New Theories Unlocking the Mystery of the Dinosaurs and their Extinction. New York. Kensington Pub. Group.
Carpenter, K. 1998. Armor of Stegosaurus stenops, and the Taphonomic History of a New Specimen from Garden Park, Colorado. Mod. Geol. Vol. 23:127–144.
Carpenter, K., Galton, P.M. 2001. Othniel Charles Marsh and the Myth of the Eight-Spiked Stegosaurus. in: Carpenter, K. (ed) The Armored Dinosaurs. Bloomington. I.U. Press. pp: 76–102.
Carpenter, K., Sanders, F., McWhinney, L.A., Wood, L. 2005. “Evidence for Predator-Prey Relationships. Examples for Allosaurus and Stegosaurus.” in: Carpenter, K. (ed.). The Carnivorous Dinosaurs. Bloomington. I.U.Press. pp:325-350.
Coombs, W.P. 1995. Ankylosaurian Tail Clubs of Middle Campanian to Early Maastrichtian Age from Western North America, with Description of a Tiny Club from Alberta and Discussion of Tail Orientation and Tail Club Function. Can.J.Earth.Sci. Vol. 32:902–912.
Fronimos, J., Wilson, J. 2014. Concavo-Convex Intervertebral Joints in Sauropods and Crocodylians: Do They Increase Flexibility or Stability? J.V.P. Vol. (35): Supp1:133A
Gilmore, C.W. 1932. On a Newly Mounted Skeleton of Diplodocus in the United States National Museum. Proc.U.S.Nat.Mus. Vol. 81:1–21.
Gilmore, C.W. 1914. Osteology of the Armoured Dinosauria in the United States National Museum, with Special Reference to the Genus Stegosaurus. U.S.Nat.Mus.Bull. Vol.89:1–143.
Irschick, D.J. Jayne, B.C. 1999. Comparative Three-Dimensional Kinematics of the Hindlimb for High-Speed Bipedal and Quadrupedal Locomotion of Lizards. J.Exp.Biol. Vol.202:1047–1065.
Lull, R.S. 1910. Stegosaurus ungulatus Marsh. Recently Mounted at the Peabody Museum of Yale University. A.J.Sci. vol. 30:361–377.
Mallison, H. 2010. CAD Assessment of the Posture and Range of Motion ofKentrosaurus aethiopicus Hennig 1915. Swiss. J. Geosci. Vol. 103:211–233.
Marsh, O.C. 1891. Restoration of Stegosaurus. Am. J. Sci. Ser. 3. Vol. 42:179–181.
Marsh, O.C. 1877. New Order of Extinct Reptilia (Stegosauria) from the Jurassic of the Rocky Mountains. Am.J.Notice.Sci. Ser. 3. Vol. 14:14:513-514.
Norman, D. B. (1980). On the Ornithischian Dinosaur Iguanodon bernissartensis from the Lower Cretaceous of Bernissart (Belgium). Mem. Inst. R. Sci. Nat. Belg. 178:1-105.
Padian, K., Olsen, P.E. 1984. Footprints of the Komodo Monitor and the Trackways of Fossil Reptiles. Copeia. Vol.3:662–671.
Persons, W.S., Currie, P.J. 2011. The Tail of Tyrannosaurus: Reassessing the Size and Locomotive Importance of the M. Caudofemoralis in Non-Avian Theropods. Anat. Rec. Vol. 294:119–131.
Stevens, K.A., Parrish, J.M. 1999. Neck Posture and Feeding Habits of Two Jurassic Sauropod Dinosaurs. Science 284(5415):798–800.
Stevens, K.A. Parrish, J.M. 2005. Digital Reconstructions of Sauropod Dinosaurs and Implications for Feeding. in: Curry Rogers, K.A., Wilson, J.A. (eds) The Sauropods: Evolution and Paleobiology. Berkeley. U. California. Press. pp:178–200.
Schwarz-Wings, D. 2009. Reconstruction of the Thoracic Epaxial Musculature of Diplodocid and Dicraeosaurid Sauropods. J.V.P. Vol. 29(2):517–534.
Taylor, M.P. 2014. Quantifying the Effect of Intervertebral Cartilage on Neutral Posture in the Necks of Sauropod Dinosaurs. PeerJ. 2:e712.
Taylor, M.P., Wedel, M.J., Naish, D. 2009. Head and Neck Posture in Sauropod Dinosaurs Inferred from Extant Animals. Acta.Pal.Polon. Vol.54:213–220.
Tsuihiji, T. 2004. The Ligament System in the Neck of Rhea americana and its Implication for the Bifurcated Neural Spines of Sauropod Dinosaurs. J.V.P. Vol. 24(1):165–172.
Wedel, M.J., Taylor, M.P. 2013. Neural Spine Bifurcation in Sauropod Dinosaurs of the Morrison Formation: Ontogenetic and Phylogenetic Implications. PalArch. J.V.P. Vol. 10(1):1–34.
Willey, J.S., Biknevicius, A.R., Reilly, S.M., Earls, K.D. 2004. The Tale of the Tail: Limb Function and Locomotor Mechanics in Alligator mississippiensis. J.Exp.Biol. Vol. 207:553–563.

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10 Responses to Jurassic World and the case of the droopy-tailed Stegosaurus

  1. Avatar Sean H.
    Sean H. says:

    I can’t help noting that even given the paleo-progessive theories & designs displayed back in 1993, JP’s sundry advisors & directorship have laced the franchise with artistic license well prior to Plumagegate & the latest sequel: frill-necked dilophosaurs, tripod-rearing brachiosaurs, piranha-swarming compsognathids, ‘angry’-browed tyrannosaurs, bite-proofed spinosaur, toothy Pteranodons…with a track record like that, I’m still surprised the second novel’s chameleon-pigmented Carnotaurus never got their turn on film. Compared to all that, I’d call JP’s stegosaur-handling downright sedate, though color me skeptical about (a) Stegs galloping as seen later in several previews (b) the safety factor of those hamster-balls in proximity to a hadrosaur group, never mind any big sauropod and (c) that many elephant-plus-scale herbivores of sundry species gracefully handling such proximity within the limited grazing room of an island preserve.

    Anyhow, your notes on potential tail-flexibility & supporting structures are much appreciated. Strikes me that stegs with the thagomizer fixed at a given altitude would have that much more trouble puncturing lower-slung (or at least lower-striking) aggressors…I recall one posited scenario in a Luis Rey-illustrated book where one theropod harried a Tuojiangosaur face-on whilst its partner darted in to nip around the tail-base & cloaca. Ouch.

    • Supposedly Indominus rex does have the Carnotaurus chameleon (though more like cephalopod) ability from the book. It’s too bad they didn’t just up and put Carnotaurus in the film, but when one wants bigger and badder I suppose a 9 meter theropod just won’t cut it. Interesting thoughts on Stegosaurus and smaller theropods. One wonders if the overall size of the adults was enough of a deterrent for smaller predators.

      • Avatar Sean H.
        Sean H. says:

        Seems likely that with the vertical range of stegosaur tail-motion you propose, rear-attackers might not have much more ducking clearance than Julianne Moore’s character did in the first sequel, where she narrowly avoids a thagomizin’ by dropping flat. And as you note, most carnivores that low-slung likely had safer things to chew on (including the odd steg yearling), though I’d love to know whether any Late Jurassic crocodilians approached Sarcosuchus or Deinosuchus in bulk.

        As for I.rex…adding squid-camo to that brute’s grab-bag of already meta-saurian tricks? Now I’m half-expecting a tie-in Royal Rumble with King Kong. Come to think of it, the beastie already looks like Dr. Wu & crew patched up allosaur stock with genetic material from the 2005 remake’s snaggletoothed, osteoderm-heavy ‘Vastatosaurs’. And here I’d have settled for Vince Vaughn’s eco-saboteur getting blindsided by a Stealth Abelisaur back in 1997.

  2. [Editor’s note: I tweaked the comment to fix the formatting]

    Overall a very nice piece, much better than some other reactions I’ve seen to that oh-so brief snapshot. It’s nice to see tail’s get some attention as well. They’re one of the most obviously dinosaurian (and reptilian!) features we notice, but they always seem brushed aside. Your pointing out of posture variation in animals reminds me of this.

    Two things:
    (1) I’ve gotta say, I’ve found much of the backlash against Jurassic World to be overblown. Certainly, Treverrow and co. have gotten a lot wrong (intentionally, in a couple cases. One must wonder what Jack Horner actually does to get an “advisor” credit), but is that such a big deal? Certainly, if this were a movie about the theory of evolution, or climate change, or vaccines, and the science was completely wrong, then that would be a huge blow to scientific communication. But a “Velociraptor” without feathers, or King Kong style pterosaurs? Is that really such a slap in the face? It is important, I think, to take a step back and look at the bigger picture here, and that the “truth” to be found in the Jurassic Park series (at least the first one, and hopefully World) is that these animals existed (emphasis on the animal part!), and were unique and diverse in form. That’s something the general public are only vaguely aware of, and a not-insignificant number of people are wholly ignorant about. Either way, the scientists win, because when kids walk up to me and ask me about Velociraptor I get to say “Gee, y’know that multi-million dollar movie Hollywood made? They got it completely wrong!” And then I can use that as a springboard to talk about a host of other stuff.

    (2) Your comment at the beginning of the post intrigues me.

    Never mind the fact that a feathered, pack-hunting, 2 meter tall Velociraptor mongoliensis is still every bit as inaccurate as a scaly one.

    Are you saying that Velociraptor is just as likely to have been scaly as it was feathered? I don’t mean to stir up the pot, but don’t the quill knobs found back in 2007, or do you find those suspect? Just curious.

    Thanks,
    Ruger

    • Ah damn, I messed up the formatting there. Sorry bout that.

    • Hi Ruger, I hope you don’t mind that I tweaked your comment to fix the formatting. I’m currently looking into allowing editing of comments by users (I’m still getting the hang of the new theme).

      I agree that the backlash against Jurassic World seems way overblown. When scientists get ticked at the portrayal of science in documentaries I can understand it, but for a movie? Yeah it can be disappointing when we see what the popular thinking of dinosaurs still is (so many people still ask me how “we know” that T. rex couldn’t see movement), but we shouldn’t be surprised when we see that thinking expressed in a movie. The thing about the backlash that really bothers me is how many in the paleo community are mad at Jurassic World for ushering in a new generation of people to false ideas about dinosaurs. Yeah, Jurassic World will spark the zeitgeist’s interest in dinosaurs again, but it’s going to be short-lived. The Lost World: Jurassic Park didn’t really spur the public’s interest in Stegosaurus and just 8 years after Jurassic Park 3, Discovery Channel released a documentary on Spinosaurus called: The most terrifying dinosaur you’ve never heard of. Jurassic Park was a game changer for the popular images of dinosaurs. The same cannot be said for its sequels.

      Regarding my feathered Velociraptor comment I could have worded it better. I’m not denying that we have good evidence for feathers in dromaeosaurs. I only meant that there seems to be this attitude among some paleofans and paleontologists that lack of plumage is the number one problem for all dinosaur reconstructions and that sticking feathers on the animals somehow magically erases all the other problems with the anatomy or inferred behaviour.

      Cool John Conway link by the way. It’s nice to see these variations in the standard dinosaur poses.

      • Avatar Ruger
        Ruger says:

        No problem at all, in fact I very much appreciate it! Thanks for the response, I don’t find anything at all to argue with. I will point out though, it has been 14 years since the last Jurassic Park film, and 22 years since the last good one. I think Jurassic World has enough momentum to boost interest in dinosaurs. Certainly not to the effect that JP did, but I won’t be surprised if we see a slight increase in children’s books, documentaries, and hopefully, museum attendance.

        Thank you for the clarification. I had thought that was what you meant, but I try not to assume.

  3. Having seen and enjoyed the film yesterday, I recall Dr. Wu saying that since the dinosaurs in Jurassic Park/World are all “hybrids” to one degree or another, none of them perfectly match their genomes’ prehistoric source material in appearance. That for me was a satisfactory handwave. It at least states the representation of dinosaurs in these movies isn’t to be taken at face value with regards to the real animals, which could potentially direct the public to finding more accurate information. And that would be easier to do in today’s Google age than back in 1993.

    At any rate, I’ve learned that the people who act the most militant about “paleontological accuracy” often have their own pet misconceptions about dinosaurs (e.g. the feathers issue you’ve discussed so many times on your blog), so I wouldn’t take their words without question either.

  4. Why should a stegosaur have necessarily a drooping tail? Wasn’t its tail strong enough to be kept horizontal with minimum energy spent even in rest? Also, as quadrupedal dinosaurs evolved from pibedal ones with the theropod configuration, they could have retained the ancestral tail carriage.
    I find it more logical that mammals can have droopy tails, as they are small and delicate structures compared to reptilian ones, so a little tail sticking out is prone to injury. Also, many big mammals use them primarily for swatting insects, so they don’t have any major other function to be kept straight back.

    • Stegosaurs could have had their tails held aloft all the time. It’s not impossible. However, there’s not much reason for it either. Animals are generally thrifty in terms of energy expenditure. Keeping the tail held out straight during walking bouts (where the pull on the caudofemoralis is greatest) makes sense, but keeping it aloft while standing around grazing, doesn’t. Similarly, keeping aloft the part of the tail that the caudofemoralis attaches to makes sense for walking, whereas keeping the rest off the ground is less important (unless drag from the tail becomes a problem). I suspect Stegosaurus and other dinosaurs held their tails in a variety of positions throughout the day. I just wish more paleo-art would reflect this.