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 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.
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:
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:
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:
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.
I don’t think this picture does justice for it, so here’s what it may have looked like next to a standard Triceratops:
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.
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.
That’s nice and all, but then you have to consider this guy here:
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:
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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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.