By Carlos Augusto Chamarelli
As my friends know very well, I’m a fervent opponent of Jack Horner’s ideas. So naturally I had to start a series for analyzing and counter attacking some of his wackiest theories about dinosaur which, I hope, aren’t brainwashing an entire generation of paleoartists. Let’s get to know the star of the first post of the series: the Triceratops.
People might remember some time ago, it was everywhere in the news: “Triceratops didn’t exist”. That’s BS, even Horner himself said so. What he actually meant is that the ceratopsian dinosaur Torosaurus is nothing but an aged Triceratops: over the years the frill of – presumably male only – Triceratops would grow to the astounding size of Torosaurus‘ frill, about 2.5 meters (8.5 feet) long.
So in reality what should have been in the news is “Torosaurus didn’t exist”. In zoological nomenclature, a basic principle is that when a species received two different names, the earliest correctly published name, called senior synonym, takes precedence and thus should be used to name the species, excluding the later name (junior synonym). And since Triceratops was named before Torosaurus, Triceratops is the senior synonym and has to be the official one. But naturally media figured most mainstream people don’t know what a Torosaurus is, so their solution was to mess everything up and make some sensationalism, because that’s very surprising.
Naming issues aside, there are a few points about this theory that just seem off to me:
A little less known aspect of Horner’s theory (or maybe not so much anymore since he already released a paper about it) is that before becoming Torosaurus, Triceratops became something else first, and that is Nedoceratops (formerly Diceratops).
Nedoceratops skull. Photos by Andrew A. Farke, from Wikipedia, 2011
Nedoceratops have a long history of debates about its validity as a separated species or as a synonym for Triceratops (the small windows in the frills simply being caused by pathologies, for example). For Horner, the holes in the frill indicate the beginning of the transformation into Torosaurus, but that’s about where things get weird.
Drawing of the two Torosaurus skulls by Marsh, 1893.
Really now, how exactly does a hole form outta nowhere? So okay, Horner demonstrates that Triceratops’ frill is not entirely solid, some areas are thinner, and these are about the same areas where the holes appear in Torosaurus, so it apparently makes sense Torosaurus to be an old Triceratops, but even if dinosaur’s bones were very plastic and enabled many transformations as they grew, the bone retroceding and becoming so thin to the point where it disappears and leaves a hole is something not even sheer open-mindness is able to accept.
Reason number one is ceratopsian growth in general. Let’s use Protoceratops as the example since there are plenty of skeletons from individuals of varying ages, from baby to adult:
Protoceratops growth series. Photo by Harry Nguyen, 2008.
As you can see, the holes in the frill are present even in the youngest individuals. And if people can use Psittacosaurus quilled tail as an excuse to put quills in all other ceratopsians tails, then darn it, I WILL use baby Protoceratops as an argument that baby ceratopsians maintain holes in their frills all the way to adulthood, which takes us to reason number two, which is the baby Triceratops skull itself:
Baby Triceratops skull casting. Photo by BrokenSphere, from Wikipedia, 2009.
It’s not known (for me, at least) how old this baby was when alive, but judging by his size and features, he might very well been a newborn. Anyway, let’s take a look at his frills:
Baby Triceratops frill detail. Photo by Brokensphere, from Wikipedia, 2009.
So there, he does have some kind of holes in his barely formed frill. But these quickly disappear, as shown by the rest of the growth series. Maybe the thinner areas of Triceratops’ frill is a heritage of his baby form, maybe that part is naturally thinner for whatever reason. The point is that if it was true that Torosaurus is an old Triceratops, then the holes should have been present in all the younger forms just like Protoceratops, no matter how small they are compared to other ceratopsians.
But I give credit where credit is due. Horner presented solid evidence: the bones of Triceratops are spongy, which is characteristic of young individuals, which means that, true, Triceratops may not represent fully grown individuals. Still, it’s a long shot to assume Torosaurus is the mature form.
There is one little detail Horner overlooked in his theory: there IS a dinosaur that is bigger and is similar to Triceratops – even more than Torosaurus –, and whose remains were found in the Horseshoe Canyon formation in Alberta, which not only isn’t that far from Montana, but is also known to contain remains of dinosaurs also present in the Hell Creek formation, including Triceratops.
This dinosaur is called Eotriceratops xerinsularis, described in 2007 by Xiao-Chun Wu, Donald B. Brinkman, David A. Eberth and Dennis R. Braman.
Eotriceratops skull casting. Royal Tyrrel Museum, 2010.
I don’t think this picture does justice for it, so here’s what it may have looked like next to a standard Triceratops:
Eotriceratops size compared to Triceratops. Image by Conty, from Wikipedia.
There are some debates over the total lenght, but it’s quite larger than Triceratops. But then you can say “but PK, doesn’t ‘Eotriceratops’ mean “early Triceratops’? How can he be an adult Triceratops if he lived before Triceratops?”. Evidently the temporal range is estimative, and might not be entirely accurate; giving an error margin for this estimative, Eotriceratops would still be at the same time of Triceratops. If anything, Eotriceratops is the one that should have been theorized to be the aged Triceratops and be considered a synonym.
In his lecture Horner tries to argument there hasn’t been found any juvenile Torosaurus, but that’s false syllogism; I could, for example, argue that pterosaurs gave birth to live offspring since pterosaur eggs were never found. Except they were found, a few years ago, and they were soft-shelled eggs, for everyone’s surprise. What’s with this, you ask? Soft-shelled eggs are usually found in species that don’t take care of their offsprings, so this implicates that the scenario of mama pterosaur nurturing her babies in a nest, like birds do, is unlikely – but there might have been an exception here and there.
A female pterosaur preserved together with her egg. Lu Junchang, Institute of Geology, Beijing. Taken from CBC.
In other words, no juvenile Torosaurus was found because paleontologists have to rely on luck and patience, but some day they will be rewarded with such discovery. They found Tiktaalik, so why not?
The final hole in Horner’s theory is ceratopsian speciation. Amusingly enough, Horner himself kind of deliver that one: Early in his presentation, Horner show the growth series of the double-wattled cassowary, Casuarius casuarius, showing how different younger forms are compared to adult forms, and how the same thing could be applied to dinosaurs that could have been mistaken for separated species.
Double-wattled cassowary, Casuarius casuarius, growth series. Extracted from Horner's lecture "The Shape-Shifting Skulls of Dinosaurs".
That’s nice and all, but then you have to consider this guy here:
Dwarf cassowary, Casuarius benetti. Photo from Zoo Institutes.
This is the dwarf cassowary, Casuarius benneti, and if the name is any clue, he’s a smaller cassowary. He’s native to Papua-New Guinea and nearby islands, but his range also overlaps with the population of double-wattled cassowaries, and his skull looks like this:
Dwarf cassowary skull. Photo from Bird Skull Collection (skullsite.com).
So comparing it with the double-wattled cassowary growth series, things get kind of interesting, because the dwarf cassowary’s skull looks a lot more like a younger form of the adult double-wattled cassowary. You could easily put the dwarf cassowary skull in the diagram and pretend you didn’t know these were different species.
Now think of a place with lots of similar species, such as the African savannah and its wounderful antelope species variety. Some might have similar characteristics one to another, but they are all unique in their own right, even if their skeletons are virtually identical.
Naturally if you were some kind of alien paleontologist in the future and you dug up antelope fossils, you could too think that the tiny dik-dik is just a baby gazelle, which in turn is the younger form of the sable since all you have to work with are their bones.
Maybe the reason Torosaurus looks a lot like Triceratops is because they are very closely related, and might have lived in the same areas, but this doesn’t mean they are one and the same.
In the end, Horner’s idea is just slightly interesting, but is inherently flawed. Some say what he’s doing is constructive trolling, making outrageous theories to incite other paleontologists to show their work. That would be acceptable (if a little annoying indeed), but my credibility on him was buried for good in the very first episode of Terra Nova, where he’s the paleontological consulter, and allows one character to point out that the brachiosaur “supplement their diets with small reptiles”. Damn.
Anyway, I hope you enjoyed this article, and as usual, any questions all you have to do is comment and I’ll answer it.
Thanks for reading!
For more about dinosaurs, you might want to see:
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References:
Scannella, J., & Horner, J. 2011. ‘Nedoceratops’: An Example of a Transitional Morphology PLoS ONE, 6 (12) DOI: 10.1371/journal.pone.0028705
TEDxVancouver – Jack Horner – The Shape-Shifting Skulls of Dinosaurs . 2009. Available on-line in: <http://www.youtube.com/watch?v=xYbMXzBwpIo>. Acess on December 5, 2011
Wikipedia. Triceratops. Available on-line in: <en.wikipedia.org/wiki/Triceratops>. Acess on December 5, 2011.
Wikipedia. Eotriceratops. Available on-line in: <en.wikipedia.org/wiki/Eotriceratops>. Acess on December 5, 2011.
You didn’t so much falsify Horner’s (or rather, John Scannella’s) claims as offer alternative — sometimes ad hoc — explanations of the same evidence.
I’m not quite sure what you meant by that, but if you could elaborate which points exactly you think are faulty I would be happy to explain my thoughts on them.
Thanks for the critic
I’d like to say that while you offer an alternative explanation, to falsify the arguments John Scannella and Jack Horner offered requires having data that shows their argument is wrong. However, that isn’t really necessary because their argument doesn’t necessarily prove their own case. The issue here is that you merely need to argue that Scannella and Horner haven’t demonstrated proof of their own argument, merely analogy to it. As you note (and so do they, in fact!), closely related animals will have similar developmental trajectories and involve many of the same morphologies changing the same way over time. Problematically, they haven’t shown a way to discriminate closely related adults with similar or identical juveniles, and the argument they pose is that while they have looked they cannot find any dissimilar near-adults that do not match a trajectory that includes Nedoceratops hatcheri and Torosaurus latus within it. Almost certainly, demonstrating they cannot discern closely related taxa at less than adult stage is enough to push their identification of juveniles to particular sides of this debate into doubt. But that requires more substantial work, and the full argument of species separation and evolutionary development, including stratigraphy, hasn’t been published yet, so this argument would also have to wait until much more of the data in favor of Scannella and Horner’s side is available.
Incidentally, the small, baby Triceratops (UCMP 154452) doesn’t really seem to preserve parietal fenestrae; what is present as a large open fracture on one side is apparently closed on the other. See this mock up for clarification.
The horseshoe Canyon formation is solidly earlier (much earlier) than the Hell Creek formation. I’m not sure where you’re getting the idea that the chronology of Eotriceratops may be wrong, but unless its locality was mis-reported, I don’t think there’s any way this can be the case.
However, this is a major issue in Horner’s hypothesis that still needs to be addressed. Somebody needs to publish a detailed stratigraphic (and chronological) diagram showing the relative positions of all known skull specimens before anybody should say this issue is near being resolved, or before we can determine how many distinct species/populations we have and how they morphed into each other over time. The situation is far more complex than simply Torosaurus/Triceratops. We’re likely dealing with numerous chronospecies here.
That would be acceptable (if a little annoying indeed), but my credibility on him was buried for good in the very first episode of Terra Nova, where he’s the paleontological consulter, and allows one character to point out that the brachiosaur “supplement their diets with small reptiles”.
That’s almost certainly true and has been mentioned on SV-POW and elsewhere, IIRC. Large sauropods would certainly have taken small vertebrates as they vacuumed up massive quantities of leaves in their daily lives. Even cows accidentally ingest small animals, and sometimes actually prey on them purposefully for calcium and protein.
Not that much on Terra nova should be taken as fact, but don’t blame the science consultants. They’re usually hired to lend fake credibility and then totally ignored by producers who just want stuff to be as cool and sensational as possible
Consultant means he advises, but he’s not the final word. This happens to science advisers in Hollywood all the time.
“You could easily put the dwarf cassowary skull in the diagram and pretend you didn’t know these were different species.”
Sorry to tipple post but i just noticed this :/
You could do that and, lacking any evidence to the contrary, you’d be justified in thinking a dwarf cassowary was a juvenile of a contemporary species. You’d be wrong, but you’d be using parsimony and assuming the simplest explanation (juvenile of a known species) is better than a more complex one (new, dwarf species). If you hear hoof-beats, think horses, not zebras.
Now, if you performed actual science to test your idea (bone histology, etc.) you might discover evidence that is contrary to the idea that the dwarf skull is a juvenile (adult bone patterns, for example). This would lend credibility to the alternative, complex hypothesis (new dwarf species). Or you might not have enough evidence to test it either way, in which case some would say you should stick with the simple explanation (juvenile) and some would say you should stick with the complex (dwarf). If neither has any data backing it up, it’s a toss up and we must admit we may never know for sure, pending more evidence. At that point it becomes a matter of philosophy, like lumping vs. splitting. But let’s not pretend we can’t support these hypotheses either way using the scientific method.Usually there is some way to test these hypotheses but nobody gets around to ever doing it.
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Sorry everyone for the late, late reply; I was away and had no internet connection and when I came back I didn’t had much time. Anyway:
@Jaime A. Headden:
In retrospect, this post may be in fact a bit hasty, but I judged it necessary to be pointed out nonetheless. I belive my real problem with this theory in general is the overacceptance; surely people with deeper understanding of dinosaurs can dismiss Horner’s theory (ok, it’s Scanella’s, but he’s like Horner deputy, so basically it’s talking about the same person in this) as nothing more than a wacky theory, but other people simply accept it as fact with little to no critic.
And thanks for that picture! It still tells me this section of the triceratops frill is just thinner than usual and prone to be damaged like that. Curiously, Nedoceratops also have a hole in just one side in the upper part of the frill.
@Matt Martyniuk
That’s one long reply there, but no problem triple posting if you have something to say.
1- As far as I know the Horseshoe Canyon is dated from late Campanian to early Maastrichtian, while Hell Creek is exclusively late Maastrichtian; still, they are just a few million years apart and wouldn’t be that much earlier in geological terms. In adition there are a few dinosaurs common to both places, such as Edmontosaurus and Pachycephalosaurus, but maybe my sources are wrong?
2- Very true. It would be nice to see this for other dinosaurs such as Tyrannosaurus and Pachycephalosaurus who are others victims of the theory of growing dinosaurs.
3- I’m aware of such theory about herbivore dinosaurs ocasionally eating meat (actually just the ceratopsian-related one), but about sauropods… I don’t know, I just can’t get convinced they would actually prey on smaller animals, even on small frequency; to have any real impact in its diet those “small lizards” should be what? The size of alligators?
4- Haha, yes, but in that particular scene I couldn’t help but think it was solely Horner’s fault. Also, Jurassic Park 3.
5- That’s why this matter for me will only be solved for good when A) a juvenile Torosaurus turns up, B) a Triceratops with mature bones turns up (if you don’t consider Eotriceratops in this), or C) many more years pass and neither are found. Luck and patience…
Also, as stated in the above reply for Jaime, my real issue with the theory is the overacceptange: Horner simply came up, said “Torosaurus is an old Triceratops, deal with it”, and that’s it.
“In adition there are a few dinosaurs common to both places, such as Edmontosaurus and Pachycephalosaurus,”
Those aren’t dinosaurs, they’re groups of dinosaurs (genera are groups of species, like families are groups of genera). First of all I don’t know of any Pachycephalosaurus species from Horseshoe canyon, except maybe mis-attributed pachycepholosaurid remains. Edmontosaurus regalis is known from horseshoe but not from Hell Creek. The Hell Creek edmontosaurs are an entirely different species, E. annectens.
“That’s why this matter for me will only be solved for good when A) a juvenile Torosaurus turns up, B) a Triceratops with mature bones turns up”
But that’s not a very scientific mindset. IF (big if) Horner is right, A and b don’t exist and will never turn up, and so you will continue to doubt their hypothesis forever. In other words, there is no way to prove your hypothesis wrong if Horner is right. At least Horner’s hypothesis can be falsified.
“Horner simply came up, said “Torosaurus is an old Triceratops, deal with it”, and that’s it.”
No, he published his hypothesis in scientific papers and has attempted to test it. other people have published papers attempting to refute it. That’s science in process. Anybody who is accepting it based on his authority with no critical thinking is in the wrong, but please don’t imply everyone who leans toward Horner being correct is an unthinking sheep.