Alien Vs. Predator Vs. Parasaurolophus

A few days ago, I sat down and, with several hours of homework to do, watched Ridley Scott's 1979 classic "Alien."  It was phenomenal, and I enjoyed it, and went on to watch Predator (great) and Prometheus (not so great).  Now, on this excellent but snowy Thursday afternoon, I'm about an hour into "Aliens," knowing that any second now an Alien xenomorph is going to appear out of nowhere and kill something.  But that's not why I paused the movie at the 54:44 minute mark.  What I've been thinking about is far more pressing: what's the purpose of that enormously distended xenomorph cranium?

If you have no idea what's going on in this picture yet, that means you're probably sane.

Usually with aliens, you can just pass off a big head as an indicator of big brains.  Ki-Adi Mundi from Star Wars, for example, has two brains in that big 'ol Cerean cranium of his, and an extra heart to boot.  If you rewatch "A New Hope" extra carefully, see if you can't spot Pons Limbic (note the brainy pun) in the Mos Eisley Cantina, the big-brained Siniteen whose head literally resembles a brain.  The Guardians of the Universe from the D.C. Comics franchise are often pretty wise, but in light of some recent events, they might not be quite as level headed and emotion spectrumless as we thought (but that's a story for another bright snowy day).  The Face of Boe from Doctor Who seems to be pretty smart, given that he's literally just a giant head in a tank and can communicate telepathically.  Then there's Zilius Zox, a Red Lantern from the D.C. universe, who also appears to be little more than a giant head.  Both Jumba (from Disney's "Lilo and Stitch") and E.T. the Extra-Terrestrial (from E.T. the Extra-Terrestrial) seem to have noggins that are larger than average in proportion to body size, and seem to have above average intelligence to match.  Marvin the Martian and Roger from American Dad?  Both smart, both big-headed.

A skull of the duck-billed hadrosaur Parasaurolophus at the American Museum of Natural History in New York, from my visit last summer with my good friend Zach Evens (who also deserves some credit listing big-brained aliens).

Now what about the aliens, or xenomorphs, from the "Alien" franchise?  Although undeniably intelligent to some degree, they aren't what you'd typically think of when the subject of brainy aliens comes up around the dinner table, at least not in terms of processing power.  But they definitely have big heads.  So what are they used for if not for thinking?  We, of course, can turn to the science of dinosaur paleontology to help us with this question.  Take a look at the dinosaur skull above.  This critter is a hadrosaur, or duck-billed dinosaur, called Parasaurolophus.  Scientists believe that it blew air through its special crest to produce a sound very similar to that of a trombone!  Many hadrosaurs had wild cranial ornamentation, as did other dinosaurs such as some of the ceratopsians and the pachycephalosaurs, just to name a few.  These wacky head-dos almost certainly had a whole lot to do with attracting a mate and sexual selection.  Essentially, the bigger your crest is, the more attractive you are.  Is it possible a similar sort of thing evolved for the Alien xenomorphs?  In "Aliens," we can see that the queen has a different head pattern than do all of the other xenomorphs that we've seen so far, indicating some sort of sexual dimorphism is potentially at work.  Interesting.  What should you take from this blog post?  Probably just that I have way too much time on my hands.

On a brief side note, I realized I've actually talked about the skull of the xenomorphs previously, before I'd even seen the movies.  Check out that post, all about otter skulls, by clicking HERE.

Alien vs. predator vs. Parasaurolophus vs. Tyrannosaurus vs. Lego Gilderoy Lockhart vs. Darth Vader vs. Polly Pocket vs. creepy frog candle vs. macaw vs. Apatosaurus vs. medieval archer vs. Boba Fett Pez Dispenser vs. Ambelodon vs. mallard vs. fisherman from an ironic fish cake vs. Jumba vs. Craire Cat Hello Thingy vs. six different types of shark vs. Taz monster truck vs. Aragorn son of Arathorn vs. Liam Payne vs. Marty from "Pirates of the Caribbean" vs. mouse cat toy vs. basilisk lizard vs. Spider-Man vs. penguins with jet packs and missile launchers vs. Themistocles vs. Terri Irwin.  And this is why it takes me so long to write a blog post.  I think we were all a little surprised about how quickly things escalated.  Yeah, I definitely have too much time on my hands.

No I Did Not Mean Triceratops, I Meant Ceratops

Recently, the folks over at the Best Western Denver Southwest purchased yet another fossil cast for their amazing hotel!*  This time, the cast is of a skull nicknamed "Judith," a specimen that is referred by some paleontologists to the dinosaur genus Ceratops.  And, no, I didn't mean to say Triceratops.  Don't feel bad if you haven't heard of Ceratops montanus: as a matter of fact, I hadn't really heard of it either until several weeks ago, when Greg Tally informed me that the Morrison Natural History Museum would soon be receiving a very large box in the mail!  Judith is still in the Cretaceous Room here at the MNHM, where she will stay for at least a few more weeks.  I really didn't know much at all about this dinosaur, and was eager to learn more.  Unfortunately, there's not much out there, as Ceratops is based on just a few bones that were discovered in the late 1800s.  Despite the lack of material, Ceratops does have a pretty fascinating history, and is an incredibly important dinosaur; not because of what has been discovered about the fossils themselves, so much as what these fossils resulted in.

Greg Tally peers through one of the fenestrae (literally means "window" in Latin) in the skull of Judith, the Ceratops montanus skull for the hotel that is temporarily on display at the Morrison Museum.  Photo Credit: Greg and Meredith Tally

When it comes to giving an animal or a group of animals a scientific classification, there are a lot of hoops you have to jump through, and a bunch of rules you have to follow.  Sometimes, groups of animals are named after the best known and understood animal in that group.  For example, Stegosaurus is the genus of dinosaur that defined the group of animals called the stegosaurs, and Tyrannosaurus is the genus of dinosaur that defined the group of animals called the tyrannosaurs.  Sometimes, it isn't quite as simple.  Think about it this way: Las Vegas is easily the most famous city in Nevada, and I'm sure I'm not the only one who spent a significant portion of their childhood thinking that Las Vegas was the capital of Nevada.  However, it is Carson City that holds the official title of capital.  Even though Las Vegas receives much more attention than Carson City, the state of Nevada isn't simply going to change where its capital is, and to the best of my knowledge, a change like that never really happens.

Although that comparison was a bit of a stretch and had about as many holes as the skull of Chasmosaurus, I think you get my point.  The same thing goes for scientific names.  Although Triceratops is the best known individual of the dinosaurian group called the ceratopsians, this group is still called the ceratopsians, as opposed to being called the triceratopsians.  That's because it was Ceratops, and not Triceratops, that was described by scientists first.

Ceratops montanus, temporarily on display at the Morrison Natural History Museum.  Photo Credit: Greg and Meredith Tally

The year was 1888, and paleontology in western North America was still going strong.  We've talked about the Bone Wars between paleontologists Othniel Charles Marsh and Edward Drinker Cope before, and we are going to revisit Marsh in this post.  To maximize the number of fossils he could describe, Marsh called upon the talents of a large number of fossil collectors, including the always brilliant Arthur Lakes in Morrison, Colorado.  Another of these collectors was a man named John Bell Hatcher.  Although Hatcher should also be remembered for a large number of his contributions to paleontology, for our purposes here we remember Hatcher as the man who discovered Ceratops.  On a trip to a known dinosaur fossil site near the Judith River in Montana, Hatcher discovered a number of fossils.  One of these fossil discoveries was composed only of a pair of horn cores.

Doesn't sound like much, does it?  Well, truth be told, it wasn't, though it was enough for Marsh to realize that he had something new.  If you click HERE, you can view the two page paper that Marsh published in 1888 that briefly described this new discovery as an animal called "Ceratops montanus."  There are several things of interest that we should take away from this paper, some of which are:

1. Marsh originally suspected that this new creature was "nearly allied to Stegosaurus of the Jurassic, but differs especially in having had a pair of large horns on the upper part of the head."  Marsh got the location of the horns right, but the close relation to Stegosaurus.....not so much.  Given the enormously tiny sampling of bones he had to work with though, it's not a surprise that Marsh compared this new animal to something that he already knew a good deal about.  Keep in mind that this is the very first scientific description of a ceratopsian dinosaur, so Marsh just had to go off of what had already been discovered.  Which was nothing.
2. Marsh notes that the "position and direction" of the horns could be likened to the enormous Meiolania, an extinct turtle from Australia, as well as the lizards in the genus Phrynosomax, the horned lizards.  He also notes that amongst the dinosaurs, the "only known example of a similar structure....is the single median horn-core on the nasals of Ceratosaurus," a mid-sized theropod dinosaur from the Late Jurassic Morrison Formation.   
3. In 1887, the year before this paper was published, geologist Whitman Cross sent Marsh a pair of horn cores about two feet in length and six inches across at their widest point.  Discovered right smack dab in the middle of where Denver, Colorado is today, Cross relayed to Marsh that they had been discovered in beds of Cretaceous rock.  Marsh, however, decided that these horns must have belonged to some sort of enormous bison, and gave the horns the name "Bison alticornis."  Perhaps Marsh was still suffering from the misconception that the 1887 discovery was, indeed, an enormous extinct bison, as these 1887 Denver horn cores are not mentioned in the brief Ceratops paper.  It is mentioned, however, that if the horns were discovered "detached," their "resemblance in form and position of the posterior horn-cores to those of some of the ungulate mammals is very striking," and the horns would "naturally be referred to that group."  I have no evidence to support my hypothesis, but I wonder whether this comparison to the mammalian ungulates is insurance on the part of Marsh, as perhaps at this point he had recognized the true nature of the 1887 horn cores.  This is pure conjecture on my part, and is mostly irrelevant anyways, as in 1889 Marsh recognized the dinosaurian nature of the Denver cores, and referred them to the genus Ceratops.  Today, these horn cores are regarded as belonging to Triceratops.
4. Marsh mentions that several limb bones, vertebrae, and teeth were also found in the Ceratops horizon, as well as several bits of dermal armor, and states that he believes they also belonged to Ceratops.  Whether this is true or not I do not know, but what I do know to be false is Marsh's next sentence, in which he states that the bones "indicate a close affinity with Stegosaurus, which was probably the Jurassic ancestor of Ceratops."  The specimen is housed in the Smithsonian today, under the catalogue number USNM 2411.  A search through the online records of the Smithosonian shows that 2411 consists only of a partial skull, which seems to be consistent with what I've read in other sources.  I'm not sure whether these other skeletal elements mentioned above have found a definitive dinosaurian home, or whether their true owner is uncertain.  
5. The final paragraph is, in my opinion, inarguably the most important.  The paragraph reads as follows: "The remains at present referred to this genus, while resembling Stegosaurus in various important characters, appear to represent a distinct and highly specialized family, that may be called the Ceratopsidae."  In this paragraph, Marsh has created the group of dinosaurs that, more colloquially, we refer to as the ceratopsians.  Or, more colloquially than that, "those dinosaurs that look like Triceratops with those horns."

Ceratops was discovered in what scientists now call the Judith River Formation.  Several other ceratopsians have been discovered in this formation, and due to the small amount and fragmentary nature of the material that was originally described as Ceratops, most paleontologists consider the dinosaur to be a nomen dubium.  Nomen dubium pretty much means that the material is too fragmentary for it to be diagnostic, and can't really be used in the future to determine whether new specimens are the same as the original or not.  Whether or not the newly discovered Judith specimen currently on display at the Morrison Museum is, indeed, Ceratops is still up in the air, as the paper has not been published yet.  Almost all of my Ceratops knowledge is out on the table for all to see, so I am not going to speculate or attempt to draw conclusions about something that I don't really know enough about to have an informed opinion on.  Guess we will just have to wait and see!  In the meantime, come on by the Morrison Natural History Museum and the Best Western Denver Southwest to see Judith, and much more!

*If you've been living underground amongst worms and fossils for the last few months, you might not have heard of the hotel, so you can check out some incredible pictures of the best Best Western by clicking HERE and HERE.

Works Cited:

Top Ten Pokémon Inspired By Real Animals

Many of you are probably familiar with the popular video game and TV series "Pokémon."  While I myself never got into it, a few months ago, I did a post about the axolotl, a fascinating little salamander. While I was researching the post (which you can view by clicking HERE), I found that a Pokémon called Wooper was based off of the axolotl.  I thought this was pretty funny, as I thought that no one had ever really heard of the axolotl, much less based a video game character after it!  The more digging I did, the more I realized that this is a fairly common theme: a great many Pokémon are based off of real animals, both living and dead!  So I thought that for the birthday post of my good friend Masaki Kleinkopf, we could look at the Top Ten Pokémon Inspired By Real Animals!

1.  Farfetch'd - Duck

According to my Pokémon sources (AKA the Internet), the Farfetch'd is supposed to live in and around water, just like a real duck!  It's also supposed to taste pretty good: again, like a real duck!

2.  Lanturn - Anglerfish

Probably one of the freakiest animals in the animal kingdom, the deep-sea loving anglerfish bait other fish closer with the so-called "esca" on its head.  The little fish swim closer, attracted to the bioluminescence emanating from the esca, and then the anglerfish snaps them up.  The name of this Pokémon is clearly an homage to this glowing appendage.

3.  Shieldon - Ceratopsian

The ceratopsians are a large group of dinosaurs containing one of the most famous dinosaurs of all time: Triceratops.  Although most sources state that Shieldon is based off of Triceratops, the Pokémon differs in that it has no horns.  This makes a more likely candidate for the origin of Shieldon another, more primitive ceratopsian called Protoceratops.  If you click on the link to a post HERE and scroll down to the second picture, you can see a picture of the skull of Protoceratops.

4.  Sandslash - Pangolin

The Pokémon called Sandslash is clearly based off of a funny, but quite fascinating, animal called the pangolin.  Sandlash features the dermal armor of the pangolin (a fancy way of saying "armor formed from hardened skin, akin to the armadillo"), as well as the massive claws.  The claws, in both the pangolin and, apparently, Sandslash, can be used to attack potential threats, as well as burrowing.  The pangolin uses its claws to burrow into termite mounds, consuming them by the thousands.  Sandslash can also roll into a ball to defend itself from attack, just like the pangolin: however, I don't think that the pangolin can roll away from its attacker while in "ball mode."  For a song about dermal armor that features, amongst many other things, the pangolin, click HERE!

5.  Relicanth - Coelacanth

Relicanth is based off of a very unassuming, but entirely fascinating, fish called the coelacanth.  For many, many years, conventional wisdom had dictated that the coelacanth went extinct at the end of the Cretaceous Period, along with the non-avian dinosaurs, the pterosaurs, and the massive marine reptiles. This assumed extinction was backed up by the fact that no fossils had been discovered, at least none that had been positively attributed to the coelacanth.  It wasn't until 1938, when a live coelacanth was pulled up off the coast of Madagascar, that scientists realized that perhaps the coelacanth wasn't quite as dead as they thought it was.  Since then, other sites along the coast of Africa, as well as in Indonesia, have yielded live coelacanths, giving the prehistoric fish a title it very much deserves: a living fossil.  According to the Pokédex in the game (a sort of encyclopedia that talks all about the different Pokémon), the Relicanth was also recently discovered, and is also labeled as a "living fossil."

6.  Tirtouga - Archelon

So apparently, some Pokémon can evolve, which is another cool and clever way of adding science into video games without making the video games dumb and boring.  Apparently, the Pokémon Tirtouga isn't necessarily based off of the massive sea turtle Archelon, but Tirtouga actually evolved into another Pokémon called Carracosta that is based off of Archelon.  Tirtouga appears to be based off of either the extant (still living, opposite of extinct) leatherback sea turtle, or perhaps another extinct sea turtle called Protostega.  Either way, all three sea turtles look pretty much the same!

7.  Archen - Archaeopteryx

It's in the name: clearly, the name Archen is based off of the name Archaeopteryx, a fossil bird that is widely considered to be the missing link (at least the first in a long line of links) between dinosaurs and birds.  First discovered in the 1800s, the feathered fossil of Archaeopteryx helped famed naturalist Charles Darwin and his followers to promote his ideas about evolution and natural selection.  According to the Pokédex, Archen is not able to fly, leading people to speculate that Archen is also based partly off of other, non-flying feathered dinosaurs, such as Velociraptor or Deinonychus.

8.  Lileep - Crinoids

Up until last week, I'd never devoted a whole lot of thought to the evolutionary relationships of a fascinating group of creatures called crinoids.  In my mind, if they look like plants, they're probably plants!  Well, I was wrong: the crinoids are actually echinoderms, just like sea urchins and sea stars, and are actually animals!  I also didn't realize that crinoids were still around today: I knew that there were a ton of them in the past, but I didn't realize that some of them had survived to the present day!  Many people believe that Lileep is based off of these strange animals, and it's not too hard to see the resemblance!

9.  Cranidos - Pachycephalosaurus

Of all of the pachycephalosaurs, Pachycephalosaurus seems like the most likely candidate for the inspiration of the strange Pokémon called Cranidos.  The main means of attack of this Pokémon is by head-butting its opponents, a means of combat long attributed to the pachycephalosaurs.  This head-butting is currently under a lot of scrutiny, with some paleontologists saying that yes, of course pachycephalosaurs head-butted each other, in the same fashion that bighorn sheep do today.  On the other hand, some paleontologists say that there is no way these guys could head-butt each other, as their necks would simply snap after a few impacts.  Other paleontologists believe that they did use their heads for head-butting, but not in the way that the previous two groups were hypothesizing: instead of getting a running start and then cracking heads, bighorn sheep style, they would instead just lock heads without the running start, like many types of deer and elk that spar today.  Still others propose that maybe these dinosaurs were smacking each other in the side or in the flank.  Like many facets of paleontology, we may never know what, exactly, they did with their craniums. 

10.  Anorith - Anomalocaris

This is the Pokémon that really inspired me to do a post like this.  Anomalocaris is one of my favorite animals because it is just so weird looking!  Living in the Cambrian Period, about 500 million years ago (MYA), Anomalocaris is definitely one of those animals that does not get a lot of the limelight.  Often found amongst the various and assorted crazies from the Burgess Shale in Canada, Anomalocaris is definitely something that I never expected to be in a video game!  Nevertheless, here it is!

This was the birthday post of Masaki Kleinkopf! Happy birthday, Masaki! If you have a birthday coming up, just email me the date at cuyvaldar123946@gmail.com with the date and your favorite animals, and I will do my best to get a post in! And if you like what you are reading, please feel free to follow us here or via Facebook!

Cal Orck'o: Not A Place for the Acrophobic

In 1994, Klaus Schütt discovered an enormous slab of dinosaur tracks.  You're probably thinking enormous like Jabba the Hutt enormous or my cat enormous.  (She's a big kitty).  But no, I mean ENORMOUS enormous.  And by ENORMOUS enormous, I mean a mile wide and 500 feet tall.  Yeah, that big.  Another thing about Cal Orck'o: its on a 70 degree incline.

Real fast, let me include a brief disclaimer: I have looked at probably 25 different books and websites that mention this place, and half of them spell it "Cal Orco," and the other half spell it "Cal Orko," while a few even spell it "Cal Orcko."  The UNESCO website calls it "Cal Orck'o," so that's the one that I went with on the blog.  So yeah, I really don't know which way is which, but nevertheless, this place is quite an interesting fossil site!

It wasn't until 1998 that Christian Meyer, a Swiss paleontologist, lead a team of scientists to investigate the site, which is near a concrete factory in Sucre, Bolivia.  They found that the enormous trackway is from the Late Cretaceous Period, dated at around 68 million years ago (MYA).  They learned that, at the time that the rocks and footprints were formed, the area was a lakeside where animals from all over would come to drink.  They also determined that Cal Orck'o was the "largest site of dinosaur tracks found so far," possessing the largest number of dinosaur footprints of anywhere in the world.

Cal Orck'o has over 5,000 dinosaur tracks made by at least six identified dinosaurs in around 250 trackways, some of which extend for hundreds of feet in a single direction.

Due to the extremely steep face of the fossil site, erosion is a constant threat to the dinosaur footprints.  The Bolivian government combats this by spending a whopping $30 million every year.  Despite this, a large chunk broke off in February of 2010, destroying around 300 footprints.   

Information on Cal Orck'o is extremely spotty, and the website for the site doesn't seem to have an "English" option.  My Spanish skills are pretty rudimentary at best, but I think I was able to come up with a list of the dinosaurs whose tracks are preserved at Cal Orck'o.  Now, keep in mind, very rarely do you definitively know what animal made a fossilized footprint, and most of the time these are simply good guesses.  For the picture below, I used ones taken from the garden area thing at the Cal Orck'o museum.  So if you are going to blame someone for inaccurate data, make sure you blame them and not me!

An abelisaur, a type of carnivorous dinosaur like Abelisaurus or Carnotaurus.

An iguanodont, a type of herbivorous dinosaur like Iguanodon.

A ceratopsian, a type of dinosaur like Triceratops or Protoceratops.

An ankylosaur, a type of dinosaur like Ankylosaurus.

A titanosaur, a type of sauropod dinosaur like Saltasaurus.

A dromaeosaur, a type of carnivorous dinosaur like Velociraptor.

A ceratosaur, a type of carnivorous dinosaur like Ceratosaurus.

A hadrosaur, a type of herbivorous dinosaur like Parasaurolophus.

A tyrannosaur, a type of carnivorous dinosaur like Tyrannosaurus.

Again, keep in mind that I have next to no idea which of these, if any, were found at Cal Orck'o.  I plan on doing a little bit of digging within the next few weeks, so hopefully I will be able to get back to you sometime soon!

Cochabamba on Dwellable

Upcoming Lecture: Animal Adventures With Zack Neher Part 1

Hey everyone!  So I just wanted to let you know that I am going to be having a trio of lectures next calendar year, and the first one is rapidly approaching!  It is on Thursday, January 10th from 4:00 PM to around 5:15 PM.  It will be held in the main auditorium at Fairview High School in Boulder, Colorado, and the address is 1515 Greenbriar Boulevard.  Admission will be free, but 90% of the proceeds will be going towards the Morrison Natural History Museum where I volunteer, while the other 10% will be going towards funding the Fairview Knowledge Bowl Team.  HERE IS THE LINK TO THE ZACK NEHER'S LECTURES PAGE ON FACEBOOK, WHICH YOU ALL SHOULD LIKE!

What will be at the lecture?  Well, just like last time, we will have a fossil table down in front, with tons of fossils, ranging from whale and bison bones to spiders preserved in amber, red fox skulls to mosasaur jaws, and much, much more! 

And, most importantly, what will we be talking about at the lecture?  Well, I am just so glad you asked!  This lecture is going to be covering a very wide variety of seemingly-unrelated topics.  But never fear, for I have artfully woven them into an intricate tapestry of fun.  Here are some of the topics and animals that we will be learning about!

• Creatures of Madagascar, including lemurs, chameleons, moths, and the fossa
• Animal names in Harry Potter
• Triceratops and its relatives
• Showy and beautiful birds, including hummingbirds and birds of paradise
• Gigantic carnivorous dinosaurs, including Tyrannosaurus, Carcharodontosaurus, Acrocanthosaurus, Spinosaurus, and Giganotosaurus
• Bird mimics, including the lyrebird, myna bird, mockingbird and catbird
• Even-Toed Ungulates (Artiodactyls), including entelodonts, camels, hippos, pronghorn, and cows
• Odd-Toed Ungulates (Perissodactyls), including horses, tapirs, and rhinos
• Why Does My Cat Do That?
• Intelligence in birds, including the African gray parrot, shrike, and crows
• And much, much more!

I guarantee that it will be a fun-filled and entertaining evening chock-full of awesome animals, amazing video, and more than a fair share of Psych references!  So please, join us if you can!  Hope to see you all there!

And please, if you like what you're reading, make sure you click the subscribe button off to the right!  

Antlers Vs. Horns, Part 2: Horns

A horn, unlike an antler, is attached to an animal.  It consists of a bony core, a projection of the bone of an animal, and is covered by a layer of keratin (your fingernails are composed of keratin).  Also unlike an antler, that falls off easily and annually, a horn, if it is broken off, will never grow back the same way.  That is why poachers have to kill rhinos (who have horns) to actually take their horns, as opposed to just letting them fall off.

Many different types of animals have horns.  Let's take a look at a few of these creatures.

The members of the family "Giraffidae," which includes the giraffe and the okapi, both have horn-like things on their heads, called "ossicones."

The members of the family "Rhinocerotidae," or the rhinos, have horns that are composed solely of keratin, and do not have the bone core typical of many horns.  The horns of the rhinos also grow continuously.

Some of the members of the family "Chamaeleonidae," or the chameleons, often have horns projecting out of their skulls, which are covered in a layer of keratin.

And, of course, the members of the family "Ceratopsidae," a group of marginocephalian dinosaurs, have horns projecting out of their skulls. 
Below is a short list of some of the more famous Ceratopsian dinosaurs.

Famous examples of Ceratopsian Dinosaurs (or "Ceratopsians That I Have Heard Of):

1. Triceratops - (Colorado, Montana, and Wyoming, U.S.; Alberta and Saskatchewan, Canada)
2. Arrhincoceratops - (Alberta, Canada)
3. Torosaurus - (Montana, North Dakota, South Dakota, Utah, and Wyoming, U.S.; Saskatchewan, Canada)
   
4. Monoclonius - (Montana, U.S.; Alberta, Canada)
5. Chasmosaurus - (Alberta, Canada)
   
6. Centrosaurus - (Alberta, Canada)
7. Styracosaurus - (Montana, U.S.; Alberta, Canada)
   
8. Achelousaurus - (Montana, U.S.)
9. Pentaceratops - (New Mexico, U.S.)
10. Vagaceratops - (Alberta, Canada)
    
11. Diabloceratops - (Utah, U.S.)
12. Albertaceratops - (Montana, U.S.; Alberta, Canada)
13. Einiosaurus - (Montana, U.S.)
14. Anchiceratops - (Alberta, Canada)
15. Mojoceratops - (Alberta and Saskatchewan, Canada)
16. Pachyrhinosaurus - (Alaska, U.S.; Alberta, Canada)
17. Kosmoceratops - (Utah, U.S.)
18. Medusaceratops (Montana, U.S.)
19. Utahceratops - (Utah, U.S.)

Keep in mind that the tusks seen in elephants, mammoths, walruses, and hippos, despite being superficially similar to horns, are actually greatly enlarged teeth!