Wednesday, 21 August 2013

Duelling Dinosaurs? Don't Believe The Hype


 
The so-called “Duelling Dinosaurs of Montana” have been in the news again but for all the wrong reasons. The specimens are being offered up for auction at Bonhams on November 19th with an estimated sale price of between 7 to 9 million dollars. The fossils which were found in 2006 on privately owned land are purported to represent two taxa – one the somewhat notorious Nanotyrannus lancensis (the so-called “pygmy tyrant”) and the other an as yet unnamed chasmosaurine ceratopsid.
Regardless of anyone’s feelings about the selling off of what is obviously an exceptional fossil pair we have to accept that this is an entirely legal and above board transaction unlike the very well publicised and highly illegal smuggling and auctioning off of a very fine specimen of Tyrannosaurus bataar last yearwhich ultimately ended up with the arrest and conviction of the main protagonist involved and the specimen being returned to Mongolia.
Now we do not have to like it or accept it but until there is a change in the law then these very high profile auctions with unique fossils will continue to occur – indeed there is yet another Triceratops skull up for auction at Christies in London in September. In this case, however, I do object to the apparent perception that the tyrannosaur is indeed a specimen of Nanotyrannus and the ceratopsid is a new chasmosaurine. Just take a look at the raft of news reports pertaining to these fossils and they all, virtually to a man, accept as gospel that the two specimens are Nanotyrannus and a new chasmosaurine. No doubt as a result of a finely tuned publicity machine designed to maximise the profit – very sad.
The truth, however is probably somewhat different. The Hell Creek Formation (HCF) is one of the most heavily sampled formations on the globe. Every year the exposure host many field expeditions, both academic and commercial, and every year there is a vast amount of research dedicated to the dinosaurs and other inhabitants of this exceptional treasure trove of fossils. Chief amongst these is the Museum of the Rockies and they have amassed one of the finest collections of Hell Creek dinosaur fossils in the world.
This collection has enabled Jack Horner, his fellow researchers and students an unparalled data resource that has been amassed over the years and the Hell Creek Project (1999 – 2010), which was a collaborative project with other institutions, produced the most comprehensive survey of the HCF ever made and included all disciplines including geography, taphonomy, stratigraphy, phylogeny, and ontogeny and this allowed the researchers to determine how abundant dinosaur skeletons were throughout the whole of the HCF.
And this is the important part – the whole of the HCF. In other words the lower, middle and upper Hell Creek Formation and not just a particular bed or section. Of course there is nothing wrong when assessing a section of the HCF but when you do not take the entire formation into account then your dataset can be misleading and errors occur.
Now regardless of whether you agree with a lot of the research and theory that has been published over the last few years is somewhat mute at this point. The controversial Triceratops/Torosaurus synonymy debate is a case in point and has featured here on this blog many times but the important point remains – that is this hypothesis was formulated because the researchers had a huge amount of data at their disposal simply because they had a vast quantity of fossils to examine which represents the largest Triceratops ontogenetic sequence ever accumulated.
So if you bear that in mind that all of these fossils have been gathered over the 12 year period of the Hell Creek Project, carrying on to the present day and then include the incredible amount of fieldwork that has been done throughout the twentieth century you have to ask yourself a question. Where are all the Nanotyrannus fossils and, apart from Triceratops, where are the other chasmosaurines in the formation?
I understand the possibility that certain dinosaurs may inhabited specific habitats. Some may have lived at higher levels away from the coastal plains and thus fossilisation would be greatly reduced. This has been suggested to explain the dearth of Nanotyrannus fossils but, when you think about it, that does not really work in any other dinosaur bearing formation in the world – especially with theropods. Large sympatric theropods are the norm now and there is lots to discuss on this issue in the near future (lots of cool research too).
So for Nanotyrannus we have the Cleveland skull (CMNH 7541) and nothing else. If you subscribe to Thomas Carr’s work, as the majority of tyrannosaurid workers do, then his 1999 paper looking at tyrannosaurid craniofacial ontogeny demonstrates that the Cleveland skull is a juvenile Tyrannosaurus, thus Jane (BMRP 2002.4.1) is a juvenile Tyrannosaurus and, ergo, this duelling tyrannosaurid is certainly another juvenile specimen of Tyrannosaurus – which would still be a very important specimen.
There is a really interesting way that the possible identity of the duelling tyrannosaur could be ascertained. Jack Horner and his team have made vast inroads into the world of bone histology at the Museum of the Rockies and, as you will have seen in the many publicity shots of the specimen, there are long bones present, so why not section one of them, check out the histology and if the results show this specimen is an adult then it would confirm the existence of Nanotyrannus and we can finally put this debacle to bed. 
But that won’t happen because a) it would affect the dollar value of the specimen and b) it would show up as a juvenile tyrannosaurid anyway. As always with Nanotyrannus I would be very happy to be proven wrong but the onus is very much on those who maintain its validity. At school my teachers would not accept that I could perform a sum in my head ( although I could) and were always saying “Show me how you worked that out” and that is what the challenge is to proponents of Nanotyrannus – show us your working out!
Just because it is a small tyrannosaurid does not make it a new taxon – goodness that is something the Hell Creek Project has clearly shown. However, I fear that the myth is far too valuable to protect and, despite the amount of evidence to the contrary, will continue to be perpetuated.
In the case of the “new” chasmosaurine the situation is even worse. How many specimens of Triceratops have been pulled from the HCF? Must be in the hundreds now (nobody actually knows). How many other chasmosaurines? None. In fact the only ceratopsid throughout the Hell Creek is Triceratops – period. So that narrows down the identity of the duelling specimen somewhat.
The supposed hypothesis leading to the basis for suggesting that this specimen represents a new taxon is based on a selection of ontogenetic and morphological disparities that are not conducive with known Triceratops fossils. Really? You do surprise me…..
With ceratopsians in particular it is extraordinarily dangerous, especially with what we know now, to base your assumptions on parts of the skull, including the parietal and horn cores, which are subject to enormous variation because of ontogeny and individual variation. You just cannot do it and, just as with the tyrannosaurid, small does not necessarily mean new. More histology required here methinks…..
So, although the specimens are both important, they are almost certainly not what they are being made out to be. And, on top of that, they are almost certainly not “duelling dinosaurs”. No the truth is probably much more mundane and they were simply two carcasses that got washed up together prior to being fossilised. Sometimes the truth is actually much simpler than people want to believe.
Reference
Carr, T. D.  1999.  Craniofacial ontogeny in Tyrannosauridae (Dinosauria, Theropoda). Journal of Vertebrate Paleontology 19:497-520.     

10 comments:

Larry Martin/fossilsource said...

Interesting perspective! All that can really be said at this point is: a) this is an extraordinary find & b) time will tell what these 2 dinosaurs actually were & how they became entangled as they are. In a perfect world, this specimen will end up in a museum where it can be properly studied.

Mark Wildman said...

Absolutely Larry - couldn't agree more.

Tom Parker said...

I have the entire time been most interested in the supposed skin impressions preserved on both animals.

Does this ceratopsid differ from the "Lane" Triceratops mummy? Does it add anything new? And most of all, skin impressions from a Tyrannosaurid!

So frustrating that this information may never see the light of day when it's sitting right there in the rock.

Denver Fowler said...

The Triceratops mummy "lane" was purchased by Houston Museum:

http://blog.hmns.org/2012/05/introducing-lane-a-mummified-triceratops-with-a-new-address-at-5555-hermann-park-dr/

It has had the skin completely prepared off the specimen so that it can be mounted as a skeleton. At least some of the skin has been kept to be displayed alongside the mount.

emailmark said...

Very interesting article Mark - I suspect this one is going to run & run. I suppose a carnosaur and a herbivore of similar size could have been swept away and dumped together and just happen to have landed up in close proximity in a duel-like pose AND sustained these kind of injuries. I so want it to be fossilized fight though! - let's just hope that it ends up in a properly accredited institution where it can be studied in the way it deserves.

Anonymous said...

Just curious Mark, now that a few more months have passed & it's been discussed ad nauseum, do you still think the deulling dinos were likely just 2 carcasses that washed together? I feel that all the evidence there is to consider at this time, points to the idea that they were interacting with each in a deadly struggle. I'd love to know if you are still thinking they are misnamed as the "deulling dinosaurs".

Mark Wildman said...

Well the first thing to say is that it is extremely difficult to postulate what the truth is about these fossils. Until both specimens are described properly which simply MUST include the taphonomy then it is not for me to speculate to be honest.

I have opinions on the ethics of this entire saga - yes - but it is wise to be a little open minded despite evidence to the contrary. I will say, however, that I have had some fascinating insight via personal communications and, at the moment, I am still inclined to believe that these specimens probably did wash up together. But I am happy to be proven wrong - the onus is on those who have or will have the possession of the specimens to do just that.

Anonymous said...

Hikaru Amano here. My wordpress acount seems to be having trouble accessing this site

Is the extent of remodeled bone tissue structure always a foolproof gauge of maturity? Although it seems logical to assume that a bone with more heavily remodeled bone tissue is older, this is only true if the rates and/or extent of bone tissue structure remodeling is consistent between and amongst different bones in different parts of an animal and different members of its species. However, the results of many studies concerning bone remodeling published in many journals show that certain factors and/or processes independent of ontogeny significantly-and at times, even radically-alter the rates of bone remodeling and/or extent of remodeled bone tissue structures in different bones of an individual(and there are times bone remodeling is even very variable at different regions of the very same bone of an individual). Factors and/or processes that significantly affect bone remodeling aside from ontogeny include: differences and/or changes in the mechanical stress regimes different bones (and/or different regions of the same bone) have been subjected to; developmental origin of different bones; health and/or nutrition of the individual, and; predominant metabolic regimes. For example, a bone from a subadult individual that has been subjected to great amounts of mechanical strain would end up having tissue structures similar to that of an old adult that have only undergone normal degree of mechanical strain. The picture gets even more complicated if one considers how some of those factors interact with one another and/or with ontogeny (and at times, even how all of those phenomena interact together) in the remodeling regime of different bones. The way some-and at times, even all-of those factors and/or processes interact is much more complex (and are either not yet understood, or discovered, or even both). As Dr. Longrich have pointed out in the video of the Yale debate, bone remodeling could be a useful tool in gauging the maturity of an animal; however, its reliability first needs to be tested much more thoroughly before we could confidently apply it to dinosaurs. Because if bone tissue structure remodeling regimes are indeed very variable, a subadult individual could have ILLUSORY OLD ADULT tissue structures due to the interaction of the above-mentioned phenomena. The following journal articles caution about the potential flaws, limitations, and misapplications of bone tissue structure remodeling.


Kini,U. and Nandeesh,B.N. (2012). Physiology of Bone Formation, Remodeling, and Metabolism. Radionuclide and Hybrid Bone Imaging, pp 29-57.

McFarlin,S.C., Terranova,C.J., Zihlman,A.L., Enlow,D.H., and Bromage,T.G. (2008). Regional variability in secondary remodeling within long bone cortices of catarrhine primates: the influence of bone growth history. J. Anat., 2008 (213): pp308–324. doi: 10.1111/j.1469-7580.2008.00947.x.

Oers,R.F.M.v., Ruimerman,R., Tanck,E., Hielbers,P.A.J., and Huiskes,R. (2007). A unified theory for osteonal and hemi-osteonal remodeling. Bone, 42 (2008): pp. 250–259.

Pazzaglia,U.E., Andrini,L., and Nucci,A.D. (1997). The effects of mechanical forces on bones and joints:experimental study on the rat tail. J Bone Joint Surg [Br] 1997;79-B:1024-30.

Ruimerman,R. (2005). Modeling and Remodeling in Bone Tissue. Netherlands: Technische Universiteit Eindhoven.

Terrier,A., Miyagaki,J., Fujie,H., Hayashi,K., and Rakotomanana,L. (2005). Delay of intracortical bone remodelling following a stress change: A theoretical and experimental study. Clinical Biomechanics, 20 (2005): pp. 998–1006.

thiago chagas said...

"So for Nanotyrannus we have the Cleveland skull (CMNH 7541) and nothing else. If you subscribe to Thomas Carr’s work, as the majority of tyrannosaurid workers do, then his 1999 paper looking at tyrannosaurid craniofacial ontogeny demonstrates that the Cleveland skull is a juvenile Tyrannosaurus, thus Jane (BMRP 2002.4.1) is a juvenile Tyrannosaurus and, ergo, this duelling tyrannosaurid is certainly another juvenile specimen of Tyrannosaurus – which would still be a very important specimen." #fucklogic do you really think that a juvenile would become 50% bigger and do not look more like the adult? Do you really think it would be jst a bigger clone of it's younger age?

Also Carr's hypothesis is fallacious, as he simply threw away the similarities with albertosaurines and said that similarities with T. rex said everything, and somewhat nonsense as such growth pattern does not match in the "skull growth pattern" of even distantly related groups such as birds and mammals. You said that nanotyrannus was a juvenile T. rex, but did not show the arguments of the authorities and not even your arguments. If you say that something is true, you must give reasons for people to agree with you.

Mark Wildman said...

Thomas Carr - fallacious? Is that what you actually said? Very well...

Nanotyrannus was named on the basis of the original description of the Cleveland skull by Bakker at al in 1988. Fair enough. Since then the original diagnosis of this skull was tested by Carr in 1999 where he demonstrated that the specimen is a juvenile T.rex.

Remember, this is the type specimen of Nanotyrannus that has now been rediagnosed as a juvenile T.rex. In 17 years now there has not been one single hypothesis to contradict Carr 1999 - not one. Carr is the first one to say that if anybody wishes to prove his diagnosis incorrect by defending the diagnosis of Nanotyrannus then to please go ahead - that is science after all.

There has not been a single attempt at doing so. This has other implications as well. You mention my comments about Jane and the Duelling Dinosaurs tyrannosaurid. For the sake of argument, let us suppose that they both turned out to be new taxa - that would be great but they would still not be Nanotyrannus and would need new taxonomic assignment because the Cleveland skull is still a T. rex - unless it is proven otherwise.

I do not understand your previous point about change throughout ontogeny. Where did I say that did not occur? Morphological change throughout ontogeny is inevitable - I work with marine reptiles which are even more radical in their growth patterns.

I suggest that you read Carr 1999 if you have not already done so. If you do and find that you disagree with him then that is fine but then I suggest the onus is on you and others to prove the diagnosis wrong.

Incidentally there are three major tyrannosaurid works in the works for publishing in the near future. Having been privy to some of the data in these works you will find your criticism will be considerably muted and that the pygmy tyrant will be gone forever.

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