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If The Torosaurus is a Mature Form of Triceratops

Mamerto Adan is a feature writer back in college for a school paper. Science is one of his many interests, and his favorite topic.

if-the-torosaurus-is-a-mature-form-of-triceratops

Sometimes, nothing is permanent in science. Ideas must give way to newer and more accurate discoveries. Most of the time, people are okay with it, though letting go a beloved and accepted views that became obsolete could be painful, if not violent. Nevertheless, people will learn to accept, for the common good and for the benefits of the civilized world. With that said, in the paleontology world it was suggested that a dinosaur species might be just a younger version of another. If this is true, then this dinosaur species will have to go into the bowels of discarded science facts.

Not that easy to accept in this case, as the Triceratops is a beloved dinosaur by many. Whenever T-rex was mentioned, this horned dino will surely come to mind. We grow up with this mental image of a prehistoric battle between the two titans, with the T-rex and Triceratops locked in a mortal struggle. Hence if it’s true that the Triceratops was indeed just a youngling of another horned dino, then our childhood is ruined. Well, there is nothing wrong with replacing the Triceratops with another creature in the T-rex duel. People will learn to live with it right?

But we need to consult good old science before we kick out the poor thing.

It Happened Before, in the Case of the Dracorex

Too bad, because Hagrid won't be too happy.

Too bad, because Hagrid won't be too happy.

Extinction seems to be happening even in fossil studies, as in the case of an interesting find just recently. In 2004, a dinosaur skull was donated to the Children’s Museum of Indianapolis, which was dug out from Hell Creek Formation in South Dakota. Bob Bakker and Robert Sullivan made a formal description of the creature in 2006 and was named Dracorex hogwartsia (dragon king of Hogwarts) for a good reason. The skull boasts horns and spikes that made it resemble a mythical dragon. So much was its resemblance to the creatures of legend, that it got the Harry Potter school for a name. In general, the Dracorex was herbivore dinosaur with long muzzle and spiky, horny and bumpy head. It was closely related to the Pachycephalosaurus and was about 7 ft 10 in long.

But not so fast, according to renowned Paleontologist Jack Horner. During the annual meeting of the Society of Vertebrate Paleontology, he presented evidence from the analysis of the Dracorex skull, suggesting that the creature is nothing more than the female, or younger version of the Pachycephalosaurus, where the skull is still underdeveloped. He stated that the Dracorex are known only in from juvenile fossils, while the Pachycephalosaurus is known only in adult fossils. He also based his findings from the analysis and skull comparison of younger Pachycephalosaurus and Dracorex.

Bad news for Hagrid.

Then There is the Torosaurus

Reconstruction of the Torosaurus.

Reconstruction of the Torosaurus.

Back to the Torosaurus, let’s first revisit how the remains are unearthed back in 1891. It was two years after the Triceratops was named when it was found in Wyoming by John Bill Hatcher. The term Torosaurus was coined by his employee Othniel Charles Marsh. Unlike the Triceratops, the Torosaurus had a more elongated frills, with two holes.

Now, the name Torosaurus seemed to be translated as “bull lizard,” as the term “toro” is Spanish for bull, or from “Taurus,” which is Latin for bull. Unlike the Triceratops, the Torosaurus remains are rarer.

Yet the name could also be translated as “perforated lizard,” due to the holes on the frill (from the Greek verb “toreo,” to pierce).

In terms of size, this creature was never small. In fact, they are massive, the size of large Triceratops. The “brow” horns (the horns the stretch above the eyes) are long and curved outward. It also boasted a nose horn like the Triceratops.

Then there is the frill.

As what was mentioned above, the frill was longer than the Triceratops. This made the skull, based on some estimation to be 2.57 meters long.

Aside from that, there is not much difference between the Torosaurus and the Triceratops.

Why Torosaurus Could be an Older Triceratops

The Torosaurus (above) and the Triceratops skull (below).

The Torosaurus (above) and the Triceratops skull (below).

Except for the large frill with holes, the two creatures are quite similar and could be close relatives. They even shared the same habitat. But what if they were the same species, and the Torosaurus represented the final stage of maturity of the Triceratops?

The idea that the creature could be a mature form of the Triceratops was proposed by John Scannella and Jack Horner in September 25, 2009, at the conference of the Society of Vertebrate Paleontology.

Apart from the many similarities between the two creatures, Horner noted that young Triceratops have backward pointing horns, that became forward as they mature (which the Torosaurus possessed). Then, subadult Triceratops have two thinning areas in their frills. The same place where the holes of the Torosaurus frills are located. In June 2010, Horner and Scannella also suggested that another related species Nedoceratops could be a Triceratops on its way into maturing into a Torosaurus, as the holes on the frills suggested.

But Why it is Not

The Nedoceratops skull, with holes possibly from injuries.

The Nedoceratops skull, with holes possibly from injuries.

The “Toromorph” hypothesis, which suggests that the Triceratops is just a young Torosaurus was not accepted unanimously by paleontologist. They pointed out that the hypothesis is simply too inconclusive and have flaws.

The main weakness of the hypothesis is the lack of transitional forms between the Triceratops and the Torosaurus. Yes, they have the Nedoceratops which was regarded as an intermediate form. But it was challenged when Andrew Farke concluded that through the re-description of the only known Nedoceratops skull, that it was a unique species. And the holes, being surrounded by swellings were pathological in origin and not part of maturity growth (caused by disease or injury). What’s more, there was only one known skull, which made it inconclusive.

Then there was the study made Nicholas Longrich and Daniel Field. They analyzed 35 known specimens of the Triceratops and Torosaurus. They concluded that old and mature Triceratops were already represented in the fossil records, while there were also young Torosaurus fossils.

Farke also pointed out several weaknesses of the hypothesis, which includes the thinning of bone in the frill. The thin bones in Triceratops won’t lead to holes in later life but represent muscle attachments. The morphological changes that a Triceratops must undergo to become a Torosaurus must include additional bones in the frill, which does not increase when frill grows, reversion of bone structure from adult, to immature, to adult again, and the development of frill holes at a later stage than usual.

Lastly, he noted that there are Triceratop skulls with deeply veined frills, which represent advanced age, while the smooth bone structure (and unfused sutures) of the large Torosaurus specimen indicate that was a sub-adult.

Overall

The notion that the Torosaurs is an old Triceratops is questionable, given the lack of transitional forms, and the existence of a Torosaurus subadult.

Hence, we still get to keep our well loved Triceratops.

References:

1. Scannella, J. and Horner, J.R. (2010). "Torosaurus Marsh, 1891, is TriceratopsMarsh, 1889 (Ceratopsidae: Chasmosaurinae): synonymy through ontogeny ." Journal of Vertebrate Paleontology.

2. Horner, Jack. (Nov 2011). TEDX Talks: "Shape-shifting Dinosaurs".

3. Farke, A. A. (2011) "Anatomy and taxonomic status of the chasmosaurine ceratopsidNedoceratops hatcheri from the Upper Cretaceous Lance Formation of Wyoming, U.S.A."

4. Farke, A., 2002, "A review of Torosaurus (Dinosauria: Ceratopsidae) specimens from Texas and New Mexico", Journal of Vertebrate Paleontology