Thursday, November 24, 2016

Rethinking Triceratops: Part 2

In my last blog post, we discussed the phylogeny of Triceratops and its closest reptilian relatives, as well as whether it had feathers or not. In this post today, we'll continue to discuss Triceratops, and this time, how it lived and what its overall environment was like.

One thing mostly paleoartists and some paleontologists have mostly agreed recently is that Triceratops was a herd animal. Many modern scientific illustrations show Triceratops traveling across floodplains in massive herds and many paleontologists have put forth the idea, that Triceratops may have clustered together to protect their vulnerable young. However is this in fact wrong?

Up until, recently, nearly all fossils of Triceratops were found alone, unassociated with any other fossils from the same species, so paleontologists thought they lived solitary lives or in small groups, often portrayed early paleoart. Fossils recently found at sites from the Hell Creek Formation in places like Montana have in fact revealed bone beds of a few adults which died in close proximity with several smaller juveniles. Many modern-day paleontologists have interpreted this as evidence that Triceratops lived in herds. However, there could be a lot of explanations to this discovery. For example, it could have been a flash flood or the gradual deposition of fossils in streams and rivers. Until we have more conclusive evidence, we just can't know for sure either way.
Herd animal??















So moving on, how fast was Triceratops? In many illustrations from the early 20th century, when the science of paleontology was still relatively new, Triceratops was often depicted as a slow-moving animal, similar to a hippopotamus, living in prehistoric swamps or damp forests. It was also shown as being lazy and quite lethargic. However, this view has changed over the last 60 years or so.

Many paleontologists now think Triceratops was quite fast. Although it did not sprint, it still lumbered across the ground at moderate speeds. Many paleontologists have used fossil trackways as well as finger bone fossils of Triceratops to calculate its overall speed. What many of them have found is that Triceratops's speed is comparable to that of a modern-day rhinoceros, around 34 miles/55 kilometers per hour. That is quite fast! So what does this mean? In many of the older illustrations, Triceratops is shown as being too slow to combat an attacking predatory dinosaur.
Could Triceratops outrun a vicious predatory like T-Rex??














However, it is now, though, that a dinosaur like Tyrannosaurus rex would have had to have been incredibly quick to bring down one of these horned beasts. In fact, fossil bone marks suggest, that Triceratops actually killed Tyrannosaurus rex by injuring it, more than Tyrannosaurus rex actually killed Triceratops, making "three horned reptile" one of the most dangerous land animals of all time. There is actually no evidence suggesting that Tyrannosaurus rex actually ever brought down a full-grown Triceratops.
The duel of fates or just sensationalistic misconception?












Triceratops was most common in the tropical forest and delta, which deposited the Hell Creek Formation, which is about 67 to 66 million years old, which it shared with Tyrannosaurus. So aside from Triceratops, wasn't T-Rex the king of the Late Cretaceous. Fossils of a giant relative of Deinonychus and Velociraptor suggests otherwise. About 18 feet long, the Dakotaraptor, if hunting in packs, may have been serious competition for Tyrannosaurus rex, meaning that many of the old illustrations of the Late Cretaceous may have been missing an equally terrifying predator.
Dakotrarptor steini, the terror of the Late Cretaceous??














Again, Triceratops lived from 68 million to a little more than 66 million years ago, meaning it was only around for a little less than 2 million years or the last 5% of the Late Cretaceous. Although two million years seems like forever compared to our Gregorian Calendar, it is an incredibly short period in geologic time. So what does this have to do with Triceratops, and how does it make many of our assumptions about Triceratops wrong?
Triceratops lived near the very end of the "age of dinosaurs"















In many illustrations and even in some museum diorama, Triceratops is portrayed with living alongside a plethora of different Cretaceous dinosaurs. One dinosaur often portrayed as living alongside with Triceratops is the ornithopod, Parasaurolophus. However, this is very inaccurate. Parasaurolophus lived from about 76.5 to 74.5 million years ago, in what is now Canada and Montana, the same place Triceratops would have roamed around during the end of the Cretaceous. However, Parasaurolophus had been well extinct for six million years before the earliest known Triceratops lived. The same follows for many other ornithopods such as Lambeosaurus and Corythosaurus, which lived at the same time as Parasaurolophus, but were extinct by the time of Tyrannosaurus rex and Triceratops.

Parasaurlophus did NOT live alognside Triceratops



So how many species of Triceratops were there?? It was originally thought that there were at least 16 different species of Triceratops, however as the science of paleontology slowly improved, we now know there are only two species, Triceratops horridus and Triceratops prorsus, both which lived at the same time. The main differences were that T. horridus was larger and had a slightly more elongated form, while T. prorsus was smaller and had a longer nose horn than that of T. horridus, as well as straighter, shorter brow horns. 
A sketch of a Triceratops prorsus skull














The study of Triceratops also raised some problematic questions. Jack Horner, a paleontologist from the Museum of the Rockies in Bozeman, MT insists that Triceratops is really just a juvenile stage of the larger ceratopsian dinosaur, Torosaurus. He argues using fossil skulls that as Triceratops grew, it skull and frill elongated and its lost its frill horns as well. Quite a few paleontologists jumped on the bandwagon of this theory, but other have used several pieces of evidence suggest otherwise.
Is this the skeleton of a distinct Torosaurus species or just a full-grown Triceratops















For example, juvenile skeletons of both Triceratops and Torosaurus have been found and they are in fact different. Another is that paleontologists have found an "upper limit" to the size of Triceratops, about 9 meters long, while the upper size of Torosaurus is only about 8 meters long at the most. The question is still up for debate, but whether which side wins, the genus will still be named Triceratops. How? When two species are revealed to be the same, the scientific community usually uses the name for the supposed species which was discovered first. Triceratops was first officially named in 1889, while Torosaurus was named in 1891, meaning that Triceratops would be the genus name.

So as you see, paleontologists and geologists have been making wrong assumptions not only about Triceratops, but as many other prehistoric animals. This is not only limited to paleontology. Biologists, chemists, physicists, meteorologists, and astronomers have been making corrections on existing theories for the last century, and that's what science is really all about. If it were not for being wrong, what would be the point of all of it?

Sources
http://www.fossilguy.com/gallery/vert/dinosaur/triceratops/triceratops.htm

Triceratops facts

http://www.prehistoric-wildlife.com/species/t/triceratops.html

http://www.amnh.org/our-research/science-news/2009/was-triceratops-a-social-animal/

https://www.sciencedaily.com/releases/2009/03/090324081431.htm

http://phenomena.nationalgeographic.com/2015/11/25/did-dakotaraptor-really-face-off-against-tyrannosaurus/



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Rethinking Triceratops: Part 1

It is one of the world's favorite prehistoric animals and its mineralized bones can be seen in nearly any paleontological exhibit in a natural history museum, these days. Living near the end of the Cretaceous in the U.S and southern Canada, Triceratops is probably the most popular dinosaurian reptile among both the public and professional dinosaur-hunting paleontologists, after Tyrannosaurus rex.
















The exact longevity of Triceratops is 68 million to a little more than 66 million years ago, almost 10 times as long as the period between now and the very first hominid we can call a true human (Homo sapiens sapiens). Dinosaur fossils found in the Hell Creek formation of Montana, Wyoming, South Dakota, and North Dakota reveal that Triceratops, was in fact, the most common herbivorous dinosaur at the time, near the Cretaceous-Paleogene Mass Extinction. Triceratops was so common in fact, that its bones fill museum collections and it is even possibly to buy your own 67-million-year-old, authentic Triceratops fossil tooth (link below).
TRICERATOPS AUTHENTIC TEETH FOR SALE
I even have one of my own, with the original enamel patterns still preserved.

So where did Triceratops come from in the first place? An important bit of paleontological knowledge is that Triceratops is from a group of dinosaurs called the ceratopsians, which were one of the longest-lived dinosaur groups, aside from sauropods. The three main features of this group are short to long bony frills, facial horns, and large beaks. Triceratops's closest cousins in the group "chasmosaurine" are Eotriceratops and Torosaurus. Other members of "chasmosaurine," but more distantly related include Chasmosaurus and Pentaceratops.
Pentaceratops, a very closley related cousin of Triceratops















One of the other main groups of the ceratopsians was the centrosaurine, which includes such dinosaurs such as Centrosaurus, Pachyrhinosaurus, Styracosaurus, and Xenoceratops. Both these groups are part of the ceratopsids, a clade which are quite advanced compared to some of the earlier and more primitive ceratopsians.
Centrosaurus, a closely related cousin of Triceratops

















Earlier forms of ceratopsians include Protoceratops and Turanoceratops which had shorter, but still long frills compared to their body size. These ceratopsians were quadrupedal, but the earliest forms were actually bipedal and had very short frills or even none at all. These include Leptoceratops, Psittacosaurus, and Archaeoceratops. You probably can see where this is going now. The whole suborder of ceratopsia is very, very large and very, very complicated in terms of branches of evolution. The ceratopsids (chasmosaurine and centrosaurine), the dinosaurs we usually think of ceratopsians, made up only a fraction of all ceratopsians. Most ceratopsians in fact, resembled Psittacosaurus and probably were bipedal.
Pssitacosaurus, a bipedal ceratopsian













The earliest and most primitive ceratopsian known is probably Yinglong ("hidden dragon") which lived 158 million years ago (Middle Jurassic), in what is now China. It lacked a bony frill of any kind and instead had a bony shelf on the back of its skull, as well as a thick muscular tail. Yinlong was only about 3.9 feet long and a small rostral bone on its skull identifies it as a definite ceratopsian. Yinglong, although the earliest known ceratopsian, is actually not the most primitive. That seat belongs to Micropachycephalosaurus, which lived during the Early Cretaceous, and was first  thought to be a genus of pachycephalosaurid.
Yinglong, the earliest known genus of ceratopsian

Micropahcycephalosaurus, the most primitive ceratopsian known to science
































It was originally though that ceratopsians including Triceratops evolved from ornithopod dinosaurs, the same group which includes Iguanodon from the Early Cretaceous. However, it is more likely that ceratopsians descended from a much more basal creature like the species Pisanosaurus. Although the earliest ceratopsians come from the Middle Jurassic, their earliest members probably go back much farther in the Mesozoic, possibly in the Triassic.

So moving on! What did Triceratops look like? Well, when it was first identified as a dinosaur, it was portrayed usually as green-colored, scaly, and with a large robust "fat" body. It was also drawn with knobby spiny skin and long sharp horns, like a chameleon. However this notion has been long proven incorrect.

A very outdated reconstruction of what Triceratops may have looked like
















During the so-called dinosaur revolution in the 1960's and 70's, when paleontologists were rethinking long-held theories about dinosaurs, Triceratops was still depicted as before, with some differences. Ceratopsians like Triceratops were drawn as more livley agile animals and movies like Jurassic Park solidified that. Again, before this time, nearly all dinosaurs were depicted as slow and sluggish, and putting something like say...feathers on them, was considered preposterous among the scientific community.
Many paleontologists still doubt Triceratops had feathers


However starting in the 1980's to 2000's, paleontologists began digging up fossils of small meat-eating eating dinosaurs, from Cretaceous rocks in China, such as Microraptor and Sinosauropterx. These dinosaurs had died around prehistoric freshwater lake beds, and the soft deposition of sediment, preserved nearly every detail of their corpses, including...FEATHERS!

At first, it was thought that these small, carnivorous, bird-like theropods were a very small majority. Some paleontologists even stick with the assumption today in the scientific community. However, when larger dinosaurs such as the tyrannosaur,  Yutyrannus huali were discovered as having feathers, this belief began to mostly change. Today is it safe to say that any raptors or tyrannosaurs including Tyrannosaurus rex, DEFINITELY had feathers or soft fuzz of some kind or another.
Yutyrannus huali, the first known feathered "t-rex."


















So what do all this "dinosaurs with feathers" have to do with Triceratops anyway? More than you might think. Recently fossils of primtive ceratopsians such as Pssitacosaurus and ornithopods such as Tianyulong have been found with bristle-like structures, similar to feathers. Some such as Tianyulong even had these bristles, covering their entire bodies, possibly to protect themselves from possible anual cold weather or to attract potential mates.
Tianyulong was probably COVERED in feathers










As to date, it seems that nearly all dinosaurs, including the giant sauropods had some kind of fur, fuzz, or feahters of some kind. Some, such as Sinosauropteryx were probably covered in feathers, while others such as Tyrannosaurus rex, probably had a moderate ammount. The large sauropods probably had fuzz or bristles on their backs, and certatopsians such as Triceratops proabably were coated in a thin layer of fur.
Was Triceratops covered by feathers (Image photoshopped by author)




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