Triceratops: interesting facts about the three-horned dinosaur

"She was always my favorite when I was a kid, and now I see she's the most beautiful thing I ever saw," said Alan Grant in the 1993 science fiction film Jurassic Park. And that is a sentiment felt by many children and adults who have ever had even a passing interest in dinosaurs.

One of the most easily identifiable "Tyrant Lizards" is usually one of the most popular exhibits at a museum. And for a good reason, it was a very robust and tough-looking beast.

But how much do you think you know about it? Lets' find out.

What was Triceratops?

Triceratops, sometimes called a "three-horned dinosaur," was a herbivorous ceratopsid dinosaur, in the chasmosaurine sub-family, that lived in what is now North America around 68 million years ago, during the late Maastrichtian stage of the Late Cretaceous period. It had a massive bony frill that stretched up to 3 feet (1 meter), three horns on the skull, and a large, four-legged body. 

The Triceratops is one of the best-known and most loved dinosaurs of all time. It was the first ceratopsid ever found. It is known as the "classic ceratopsid" and has been shown in movies, on stamps, and in other forms of media. 

It is one of the last genera of ornithischian (bird-hipped) dinosaurs and went extinct 66 million years ago during the Cretaceous-Paleogene mass extinction. Interestingly, being an ornithischian, some of its distant relatives, the birds, are still alive today!

The Greek words tri-, which means "three," kéras, which means "horn," and ops, which means "face," are combined to form the name Triceratops, which translates roughly to "three-horned face."

It was also one of the biggest ceratopsids, with a body mass of 5 to 9 metric tons (5.5 to 9.9 short tons) and a length of up to 8 to 9 meters (26 to 30 feet). It inhabited the same habitat as Tyrannosaurus and was likely preyed on or scavenged upon by it.

But it is less likely that the two adults fought in the way that is sometimes shown in museum exhibits and other popular pictures. There has long been discussion over the purposes of the frills and the three recognizable face horns on its head. These have typically been thought of as protective weapons against predators. 

Recent theories suggest that these traits, like the antlers and horns of modern ungulates, were most likely used to tell different species apart, attract mates, and show who the boss was, perhaps including fighting for dominance. But, more on that later. 

People used to think that Triceratops was a "short-frilled" ceratopsid, but new cladistic research shows that it is a member of the Chasmosaurinae subfamily, which usually have long frills. Out of the seventeen or so species that have ever been named, T. horridus and T. prorsus are largely the only ones considered to be distinct "true" species.

Others could represent different life stages of the dinosaur. This is a fascinating phenomenon in paleontology, and we'll go into it in more detail later.

Since the first definition of the genus by American paleontologist Othniel Charles Marsh in 1888, several Triceratops specimens have been found. These include examples of Triceratops hatchlings, various adults, and other specimens thought to represent some life stages in between.

Why does Triceratops have three horns?

Since Triceratop's standout feature (literally and figuratively) is its set of three horns, you might wonder what they were actually for. Were they for defense? Or for rutting, like modern herbivores like reindeer? Or both?

This has long been debated, and without seeing the creatures in the wild, we can likely only make educated guesses. However, we know that the horns must have been relatively robust.

Triceratops had three horns: two massive ones above their eyes and a smaller horn on their snout. The two brow horns appear to have twisted and lengthened as a Triceratops aged, according to a 2006 study in the journal Proceedings of the Royal Society. During a Triceratops' juvenile years, its horns are thought to have been little stubs that curved backward. But, as the animal grew into young adulthood, the horns straightened out.

Finally, the horns would have curved forward and grown up to 3 feet long (1 meter), probably after the dinosaur reached sexual maturity.  

Today's horns are fossilized remains of what was once living bone. In life, this bone was covered in a material very similar to that in human fingernails called keratin. Technically, the term "horn" refers to the thick covering around the bone; the horn was roughly 40 percent larger than the bone. The bone inside the horn is called a horn core.

When the animal died, the keratin degraded much faster than the bone. Hence we are only left with impressions of the bone once the skeleton becomes fossilized.

Entirely what purpose they had has been debated since the dinosaur was first discovered in the late 1880s. But, the most common one for most of the intervening years had been defense.

With the addition of the neck frill, the horns could have been used as a crude spear and shield combination. The enormous frill would protect the vulnerable neck of the dinosaur, and the horns would be used for vicious stabbing and parrying.

This would prove very useful in a world cohabitated by large predatory dinosaurs like Tyrannosaurus Rex. Amazingly, there is also some evidence that combat may have occurred between these two giants of the past.

Based on partially healed tyrannosaur tooth marks on a Triceratops brow horn and squamosal, as well as a fractured horn from a previous bite that resulted in new bone growth, there is proof that Tyrannosaurus did engage in hostile head-on encounters with Triceratops.

The Triceratops likely survived the encounter because its wounds had healed. According to paleontologist Peter Dodson, a bull Triceratops would likely have the upper hand in a conflict with a Tyrannosaurus. It could effectively defend itself while inflicting lethal wounds on the Tyrannosaurus with its sharp horns.

Tyrannosaurus also consumed Triceratops, as evidenced by finding the ilium and sacrum of the latter that were severely tooth-scored. Likely when the Tyrannosaurus was feasting on the corpse.

But, the horns could also have been used to fight other Triceratops. A typical behavior among modern herbivorous animals, males often engage in combat for dominance.

Whether or not Triceratops did the same is debated, but amazingly, there is some striking evidence that encounters such as this did occur. For example, one skull has been found with a hole in the jugal bone, likely caused by a puncture wound experienced while the animal was still alive because of signs of healing.

The hole's diameter is comparable to that of the distal end of a Triceratops horn. This, along with other scars that appear to have healed on ceratopsians' heads, has been used to support the theory that these dinosaurs engaged in non-fatal intraspecific competition.  

Another specimen, known as "Big John," supports the idea that this ceratopsian used its horns for intra-species conflict by having an injury, which may have come from behind to the right side of the frill, produced by what looks to be another Triceratops horn and showing signs of extensive healing. 

Even though damage to Triceratops heads (and the skulls of other ceratopsids) is sometimes linked to horn damage sustained during battle, a 2006 study found no proof that horn thrust injuries are responsible for this type of damage. Instead, the study proposes that unidentified bone disorders or non-pathological bone resorption are put out as potential reasons.

A more recent study compared the incidence rates of skull lesions and periosteal reaction in Triceratops and Centrosaurus and found that the higher rates were consistent with Triceratops using its horns in combat and the frill being adapted as a protective structure. In contrast, the lower rates may point to a form of combat that focused on the body rather than the head or visual rather than physical use of the cranial ornamentation in Centrosaurus.

The researchers concluded that the damage seen on the study specimens was frequently too confined to be brought on by bone disease. According to histological analysis, Triceratops' frill is made of fibrolamellar bone, which contains fibroblasts essential for wound healing and can deposit bone quickly during remodeling. 

The bulky frill might have also served to increase body surface area to control body temperature.

Although this function alone could not explain the odd and extravagant variety of frills exhibited in different Ceratopsidae members, which would instead support the sexual display argument, a similar theory has been put out regarding the plates of Stegosaurus.

Paleontologist Leo Davitashvili first put up the idea that frills served as a sexual show in 1961, and it has since garnered more and more traction.

The horned dinosaurs' striking differences in ornamentation, which make each species quite recognizable, provide evidence that visual display was significant, perhaps in courtship or other social activities. Additionally, many contemporary living animals that exhibit horns and other decorations do the same. The frill and horns evolved at an extremely early age, before sexual maturation, according to a 2006 study of the tiniest Triceratops skull found, which was determined to be a juvenile, and were likely also crucial for visual communication and general species recognition. 

However, whether dinosaurs used exaggerated characteristics to identify their species has been questioned, because similar traits do not serve this purpose in contemporary animals.

Was Torosaurus a life stage of Triceratops?

As we've touched upon earlier, several claimed subspecies of the Triceratops species exist, but some leading experts in the field have challenged this.

As you are more than aware, all living creatures change in size and shape as they grow. For our species, babies are distinctly different in appearance than fully grown adults, for example, having a different number of bones. Why would this not be the case for extinct animals like Triceratops?

And this leads us gently into one of the main issues with fields like paleontology. One of the "gold medals," for want of a better phrase, in the field is to find and describe an entirely new species. In the past, this has led to the likelihood of "false positives" when classifying new species based on slight differences in physiology from accepted representatives in the fossil record.

If you were to look at fossils of a baby human and an adult human from a distance of several million years, they might be classified as distinct yet closely related species if examples were first found decades apart. Of course, this is not the case, but the fossil record is so scattered (and only usually preserves impressions of the bones) in what is preserved that you can forgive paleontologists for making "mistakes" like this.

And that completely ignores the impact of disease or genetic problems in the development of modern animals, including humans, that can significantly change the skeletal structure.

But the beauty of science is that it is never settled, and new thoughts and insights can overthrow years of consensus and, frankly, mistakes.

For example, in 2006, the Proceedings of the Royal Society journal published the first complete study of a proposed life cycle of Triceratops. According to the research of John R. Horner and Mark Goodwin, Triceratops individuals might be classified into four main ontogenetic groups: juveniles, subadults, adults, and newborns.

The youngest skull examined measured only 15 inches (38 centimeters) in length out of the 28 examined. Ten of the 28 skulls—including at least one for each age—could be arranged in chronological order in a growth series.

The four growth stages were discovered to have distinguishing characteristics. The size of the epoccipitals (small bone structures that grew around the edge of the neck frill) got smaller, the postorbital horns (behind the eye) grew and changed directions, and the horns got smaller and hollowed out.

And that brings us to another famous horned dinosaur, the iconic Torosaurus.

Two years after Charles Marsh named Triceratops, the ceratopsid genus Torosaurus was first recognized from a pair of skulls in 1891. From the study of its remains, Torosaurus was a close relative of the Triceratops, based on the age of the fossil, where the animal lived, how its body was built, and how big it was stood in life.

Torosaurus is distinguished from Triceratops by its larger head and two holes, or fenestrae, in the frill. Other than that, Torosaurus has very few anatomical differences when compared to Triceratops.

And this, as it turns out, might be critical.

Recent research by paleontologists in Montana's Hell Creek Formation on how dinosaurs grew and changed throughout their lives has shown that the lack of differences probably means the specimens exhibit a form of either sexual dimorphism or physiological changes in later life.

In a talk he gave at the Society of Vertebrate Paleontology meeting in Bristol on September 25, 2009, John Scannella reclassified Torosaurus as a very old Triceratops. Scannella's tutor, Jack Horner, supported this view by pointing out that ceratopsian heads were likely made of metaplastic bone.

This is bone that, generally speaking, forms within cartilage.

Metaplastic bones can grow and shrink throughout time, stretching and resorbing to take on different shapes. They are not something made up to fit the theory either; these can be found today in modern animals and are essential for the life cycles of most animals extant today, including us.

According to Horner, "where the horn orientation is backward in juveniles and forward in adults," significant variation is visible even in Triceratops skulls that have already been positively recognized.

The "holes" in Torosaurus skulls are in the same place as two thin parts of the frill in about half of all subadult Triceratops skulls. This suggests that the "holes" evolved to help Triceratops grow longer frills without getting too heavy.

Of course, as you can appreciate, this is hotly debated either way.

For example. apart from the frills, Andrew Farke had emphasized in 2006 that there were no systematic differences between Torosaurus and Triceratops. He still argued against Scannella's claim in 2011, saying that no other ceratopsid had ever gone through the changes in shape that would be needed for a Triceratops to "grow up" into a Torosaurus.

Some of these changes are extra-epoccipital growth, a change in the texture of the bone from adult to juvenile and back to adult, and the development of frill holes at a later age than usual.

In their study, Nicholas Longrich and Daniel Field examined 35 Triceratops and Torosaurus fossils. The scientists concluded that the fossil record shows young Torosaurus and older Triceratops that is too old to be considered babies. They concluded that the idea that Triceratops and Torosaurus were different ages of the same species could only be proven with more convincing intermediate forms than what Scannella and Horner had shown initially.

They contended that Scannella's specimen of a Triceratops with a hole in its frill might depict a sick or deformed animal rather than a step between an immature Triceratops and a mature Torosaurus form.

But, there may be a case for a relationship between more recently claimed species of ceratopsians like Nedoceratops and Ojoceratops.

Longrich has since agreed with Scannella about Nedoceratops (a three-horned ceratopsid discovered in 2007) and said that the recently found Ojoceratops (found about the same time) is likely the same animal. He said that the fossils are the same as those of the extinct Triceratops serratus that were once thought to be of the Triceratops horridus species.

Longrich pointed out that Tatankaceratops (discovered in 2010), a different recently discovered genus, had a strange mix of traits seen in adults and young Triceratops. Tatankaceratops might just as easily be a tiny Triceratops, or a Triceratops with a developmental problem that led it to cease growing early, as it could be a member of a different genus.

Of course, without DNA (or a time machine), we'll never really know.

What are some fascinating facts about Triceratops?

We've covered a lot of ground above, but if you are still hungry for more facts about this iconic dinosaur, please read on. The following list is not exhaustive and is in no particular order.

1. Triceratop's head was one-third of its total body length

To anyone whose seen a skeleton of Triceratops in a museum, one of the first things that strike you is its enormous head. Roughly 10 feet (3 meters) long, Triceratops's skull (and frill) was so big that it made up about one-third of the creature's entire length.

To put that into perspective, a human skull is roughly 15 percent or 1/6 of a human's total height. Of the other animals alive today, the blue whale has the largest skull relative to its size, roughly 18 feet (5.5m) long. That represents roughly 18-20 percent of the animal's total length.

With so much invested in such a large skull, it must have been very important to the creature in life.

2. Triceratops is thought to have lived in herds, except, perhaps, older individuals

Due to the discovery of numerous fossilized specimens of the same species in the same region, it is believed that creatures like Triceratops, and other horned dinosaurs, probably lived in herds. While many Triceratops have not been discovered together, other ceratopsids have been found together in bone beds, with examples like the "Hilda mega-bonebed" suggesting this is the case.

In 2009, researchers reported finding the first Triceratops "bonebed," which comprised three juvenile remains together and suggested a social (possibly herding) behavior to the dinosaurs.

Like herbivores today, living in a herd is an excellent way to defend against predators.

However, Triceratops may have been unique in this regard because individual remains are also often discovered, indicating that they may have lived much of their lives alone. But, this could also indicate that older males, or other individuals, would leave the herd later in life, like male elephants today.

Of course, we can't be sure.

3. Triceratops skeletons are highly prized on the open market

A wealthy dinosaur collector reportedly paid $1 million for a Triceratops specimen called "Cliff." It was later donated to the Boston Museum of Science.

According to Reuters, a professional collector found the skeleton on private land. Under U.S. law, fossils on private land belong to the landowner. Huge chunks of rock were meticulously excavated from the bones, which were then shipped to an Italian mounting company, which constructed a metal framework to hold them in place.

Cliff's skeleton weighs 2,000 pounds (907 kg) and is 9 feet (2.7 meters) tall at the shoulder (907 kg). The head alone weighs 800 pounds (363 kg).

4. Triceratops, technically speaking, only had two horns, not three

While its name stands for "three-horned face," Triceratops only had two real horns. The third, a considerably shorter "horn" on the end of its snout, was made of keratin, a soft protein similar to that found in human fingernails, and wouldn't have been much use in a fight with a hungry predator or another Triceratops.

The reason this isn't technically a horn is, technically, a horn must have a bone core as well as a keratin outer covering. This was not the case for the nose "horn" of Triceratops.

Nedoceratops (formerly Diceratops), a two-horned dinosaur, has been recognized in fossil form by paleontologists; however, some believe this may actually be a young Triceratops.

5. What did Triceratops eat?

It is believed that the primary food sources for Triceratops were bushes and other plants. According to a 1996 research published in Evolution, its beak-like mouth was best suited for grabbing and plucking rather than biting. It probably also utilized its weight and horns to topple taller plants.

According to the same Evolution study, it may have had up to 800 teeth in its jaw, continually being replaced. The teeth were grouped in 'batteries', with each battery having 36–40 tooth columns on either side of each jaw, with three–five teeth per column. Ferns, cycads, and palm trees are just a few of the vegetation it might have consumed.

Interestingly, however, some have claimed that Triceratops was omnivorous or, in some extreme cases, carnivorous, but this is hotly debated.

6. No complete Triceratops skeleton has yet been discovered

The first Triceratops bones were found in Denver in 1887 and were later sent to Othniel Charles Marsh. Marsh, at first, thought it was a bison. The creature wasn't named Triceratops until further Triceratops bones were discovered in 1888.

This would be the first of many, with, according to Scannella's 2014 PNAS article we mentioned earlier, over 50 Triceratops skulls have since been discovered in the Hell Creek Formation alone. And, as we've previously mentioned, they tend to be found alone.

No complete skeleton has yet been found, but many partial skeletons and skulls, including some from babies, have been discovered in Montana, South Dakota, North Dakota, Colorado, Wyoming, and Canada.

From these discoveries, we can confidentially say that Triceratops was restricted to North America because, by the time the dinosaur emerged, North America had already separated from Europe and had started to float across the ocean with South America.

7. There could be as many as 17, or only 2 species of Triceratops

Also, according to Scannella's 2014 PNAS article, T. horridus likely evolved into T. prorsus over 1 million to 2 million years after Triceratops. However, up to 17 species of dinosaur have been proposed since Triceratops' discovery initially discovered in the 1880s.

Lower, middle, and upper geological subdivisions of the Hell Creek Formation in Montana are the source of the dinosaur fossils that were gathered and examined for the study. According to Montana State University paleontologist and Triceratops expert John Scannella, the dinosaur most frequently recovered from the formation was Triceratops.

"We started to notice that the Triceratops in the lower unit of the formation [is] different from those in the upper unit," Scannella told Live Science.

"And Triceratops in the middle unit [has] a combination of features seen in individuals in the lower and upper units," he added.

8. Triceratops was about the size of a modern elephant

According to a 2011 publication in the journal Cretaceous Research, Triceratops was a large animal equal to an African elephant. It could reach heights of 30 feet (9 meters) and weighed well over 11,000 pounds (5,000 kg).

Though some enormous specimens reached weights of about 15,750 pounds (7,150 kg).

Strong limbs allowed it to maneuver and hold up its enormous body. The forelimbs had three hooves apiece; the rear limbs, which were longer, had four hooves each.

According to a 2012 study published in the journal Proceedings of the Royal Society B, Triceratops possessed an upright posture more akin to an elephant than a lizard, with its elbows extended.

9. T-Rex may have had to rip Triceratops' head off to eat it

There has been a great deal of discussion around whether T-Rex could have taken down an adult Triceratops. There is evidence that the two species fought, so it was likely that fatal engagements did happen. So, once a T-Rex had brought down a triceratops, how would it go about eating its prize?

Due to their thick skin and bone plates, Triceratops would have been challenging to handle even after they died. In addition, as a Tyrannosaurus, your arms aren't ideal for tearing your prey apart.

However, a recent study has revealed how it most likely occurred: head first.

In an interview with Nature News, Denver Fowler, the researcher, explained that "it’s gruesome, but the easiest way to do this was to pull the head off.”

The researchers found further evidence to support this idea when they examined the Triceratops occipital condyles — the ball-socket head–neck joint — and found tooth marks there too. "Such marks could only have been made if the animal had been decapitated," Fowler added.

Fowler and his team came to this conclusion after examining Triceratops's bones and noticing that several bite marks on the head had not fully healed. Therefore, these must have occurred after the animal had ceased to be.

This either indicates that the T-Rex used the frill to move the body around or, perhaps, ripped the head off to get to the neck and other parts protected by the neck frill.

Nice!

And that is your lot for today.

Despite being one of the most iconic dinosaurs, this species only lived for a relatively short period. In spite of that, Triceratops, like Tyrannosaurus Rex, will continue to fascinate children and adults for years to come.