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10 Bone-Headed Facts About Pachycephalosaurus

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Pachycephalosaurus’ domed, heavily-built head looks like it was capable inflicting some serious damage. Unfortunately, trying to decipher how this animal used that noggin has given many poor scientists headaches of their own.

1. Its Skull Roof was Up to 10 Inches Thick.

Pachycephalosaurus heads only reached total lengths of two feet or so. In case you’re curious, human men and women have an average skull thickness of 6.5 and 7.1 millimeters, respectively.

2. Pachycephalosaurus Heads Were Once Mistaken for Dinosaur Kneecaps.

Dinosaurs—unlike mammals—lacked kneecaps altogether. However, during the late 19th century, this fact wasn’t widely known, and few non-skull-related Pachycephalosaurus bones had been found, so this weird hypothesis is pretty forgivable.

3. One of its Close Cousins Has the World’s Longest Dinosaur Name.

Try saying this five times fast: Micropachycephalosaurus. It means “small, thick-headed lizard.” What a flattering label!

4. Pachycephalosaurus May Have Drastically Changed Shape with Age.

Dr. John R. “Jack” Horner—who, among other accomplishments, served as the Jurassic Park trilogy’s dino consultant—maintains that Pachycephalosaurus and two similar creatures which shared its habitat were really the same animal. Stygimoloch and Dracorex are smaller and had much flatter skulls. If Horner’s correct, these represent two juvenile stages of Pachycephalosaurus. He expands upon his argument at the 8:30-mark of this TED clip: 

5. It Belongs to the Same Dinosaur Clade as Triceratops.

Triceratops and its horned/frilled kin are collectively known as “ceratopsians.” Together with the pachycephalosaurids, they form a diverse dinosaurian group called the marginocephalia (“ridged heads”).

6. Perhaps Pachycephalosaurus Butted Heads.

Paleo-artists have traditionally drawn Pachycephalosaurus ramming headlong into each other musk ox-style. Does the available evidence support this?  Some scientists think so, claiming that their domes were well-equipped for absorbing such brutal impacts. Others, meanwhile, have their doubts.

7. … Or, Alternatively, Pachycephalosaurus Might’ve Preferred Flanking.

Today’s giraffes violently slam their heads into rivals’ sides. Maybe Pachycephalosaurus behaved likewise. Many of its kin had conspicuously-wide ribcages, which could theoretically withstand this sort of abuse. Also, try making two bowling balls forcefully collide at point-blank range. You’ll notice that the spheres will only briefly connect before quickly sliding apart thanks to their curvature. Pachycephalosaurus domes were also quite rounded and potentially faced the same mechanical challenge. If so, “flanking” might’ve been a more effective undertaking when tempers flared.

8. Pachycephalosaurus Had to Worry About T. rex.

Tyrannosaurus and Pachycephalosaurus both dwelled in western North America during the late Cretaceous period around 65 million years ago. That thick head was therefore possibly employed as an anti-predator weapon. 

9. Regardless, Pachycephalosaurus Could Sustain some Serious Cranial Trauma.

In 2012, paleontologist Joseph Peterson subjected a Pachycephalosaurus skull to CT scanning and found numerous potential injury marks “clustered over the thickest region of the dome,” which—in his view—seemingly corresponded with the head-butting hypothesis.

10. Pachycephalosaurus is (Indirectly) Linked to the Harry Potter Series.

To honor its dragon-like appearance and a certain best-selling book series, one new pachycephalosaurid species was named Dracorex hogwartsia in 2006. Upon hearing the good news, J.K. Rowling proclaimed “[this] is easily the most unexpected honor to have come my way since the publishing of the Harry Potter books! I am absolutely thrilled to think that Hogwarts has made a small claw mark on the fascinating world of dinosaurs.” She also added that “I can’t help but visualizing [Dracorex] as a slightly less pyromaniac Hungarian Horntail.”

But don’t get too excited, Potter fans. Remember: Dracorex could simply be nothing more than a young Pachycephalosaurus, which would make the Hogwarts-themed moniker obsolete. 

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What 6 Dinosaurs from Jurassic Park Really Looked Like
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Universal Pictures

by Alex Carter

In the 24 years that have passed since the original Jurassic Park hit theaters, what we know about dinosaurs has changed—a lot. Here's some of the new research that may change how you imagine these ancient animals, along with illustrations of what the animals may have looked like when they actually roamed the Earth.

1. VELOCIRAPTOR

Movie:

Velociraptors in Jurassic Park.
Universal Pictures

Reality:

A drawing of a Velociraptor.
Matt Martyniuk, Wikimedia Commons // CC BY SA-3.0

A far cry from the large and vicious hunters of the Jurassic Park movies, velociraptors were in fact small and covered in feathers. More like vicious turkeys, if you will. The dinosaur in the movies was based on the Deinonychus, a much larger species whose name, appropriately, means “terrible claw.” (Even Deinonychus wasn't quite as big as the raptors portrayed in the movie.) That said, other large raptors have since been discovered, including the entire genus Utahraptor. (Its discoverers originally considered naming the type species Utahraptor spielbergi in hopes that the director would finance their research, but the name-for-funds deal never went through, so it was ultimately called Utahraptor ostrommaysorum.)

2. TYRANNOSAURUS REX

Movie:

A T. Rex in Jurassic Park.
Universal Pictures

Reality:

A feathered version of a T. Rex.
A feathered version of a T. Rex.

Large. Imposing. Fluffy? Apparently, the T. rex looked much, much stranger than the beast brought to life on the silver screen. Its face might have been covered with patches of armored skin and large scales, its eyes were placed much farther forward than other dinosaurs, and it carried itself rather horizontally, not upright, as most people still imagine it. It's thought from discoveries in close relatives that T. rex was covered in some feathers for a part of its life (especially as a juvenile, as seen in The Lost World), although the details remain hotly debated. Also debated are what it used its arms for: Hypotheses have ranged from a role in reproduction to lifting itself up (which is increasingly considered unlikely) to nothing at all.

3. COMPSOGNATHUS

Movie:

A Compsognathus in Jurassic Park.
Universal Pictures

Reality:

A feathered version of a Compsognathus.
A feathered version of a Compsognathus.

This dinosaur was actually bigger in real life, although not by much. The smaller version depicted in the movies was based on what is now believed to be a young (and therefore small) Compsognathus. While many dinosaurs of its type were covered in feathers, there has been a notable lack of evidence about whether compies, as they're known, had feathers or scales. Most artists tend to draw simple proto-feathers, though; the result is an animal that looks more furry than feathery—and remarkably like a stretched rat.

4. TRICERATOPS

Movie:

A Triceratops in Jurassic Park.
Universal Pictures

Reality:

These creatures are generally portrayed as leathery and pointy—a bit like a rhinoceros designed by committee. The reality is somewhat stranger: They actually resembled porcupines. Some paleontologists believe that several nipple-shaped protrusions in their skin suggest where bristles would have been. In other areas, their skin was likely scaled rather than leathery. Their horns are another mystery. A 2009 study indicated that they were used largely for combat with other Triceratops, but they probably had a role in courtship as well.

5. BRACHIOSAURUS

Movie:

A Brachiosaurus in Jurassic Park.
Universal Pictures

Reality:

A drawing of a Brachiosaurus.

In Jurassic Park, the Brachiosaurus is the first dinosaur seen after everyone arrives on the island, memorably rearing up to get at some particularly delicious leafage. But that behavior is now considered unlikely. The book Biology of the Sauropod Dinosaurs attempted to calculate if Brachiosaurs were able to rear on their hind legs and concluded, “Brachiosaurus would have expended considerably more energy [than a Diplodocus], could not have attained a stable upright pose, and would have risked serious injury to its forefeet when descending too rapidly.” Dr. Heinrich Mallison noted that it “was probably unlikely to use a bipedal … posture regularly and for an extended period of time. Although this dinosaur certainly could have reared up, for example during mating, this was probably a rare and short-lived event.”

6. SPINOSAURUS

Movie:

A Spinosaurus in Jurassic Park III.
Universal Pictures

Reality:

A drawing of a Spinosaurus.

Joschua Knüppe, Wikimedia Commons // CC BY 4.0

The Spinosaurus was discovered only a few years after the Tyrannosaurus, but it never attracted fans in quite the same way. The fossils were destroyed in World War II during an Allied bombing raid on Munich, and the dinosaur became largely forgotten. However, Jurassic Park III resurrected the dinosaur's fame with a showdown that saw the Spinosaurus kill a Tyrannosaurus. Many fans cried foul, and the size of the Spinosaurus was indeed a mistake … in reality, it was much bigger.

It would have been up to three times heavier and 20 feet longer; a creature on the higher end of that range would have been bigger than even Jurassic World's (invented) I. rex. But could Spinosaurus have taken on a T. rex and lived? Almost certainly not. While physically bigger and armed with a bigger jaw, it was much less powerful, as most paleontologists now believe Spinosaurus used its long jaws for fishing. It actually lived mostly in the water.

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Meet Spinosaurus, the Giant Dinosaur That Was Scarier Than T. Rex
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YouTube

Contrary to what the film Jurassic Park may have led you to believe, Tyrannosaurus rex wasn't the largest—or scariest—dinosaur to ever roam the land. That honor goes to Spinosaurus, a genus of predators whose members could grow up to 50 feet long. They roamed North Africa during the mid-Cretaceous Period, around 100 million years ago.

Learn more about Spinosaurus—and the era's other fearsome creatures, which included carnivorous crocodiles and enormous flying reptiles—by watching the TED-Ed video below.

[h/t The Kid Should See This]

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