Pachycephalosaurus/Segments

## PachycephalosaurusThick-headed Lizard

* Swamps IV
* Uncovered I
* Uncovered II

## Presence

* Swamps (Segment 4)
	+ 2 adult males
	+ 8 adult females
* What Else Lived Alongside The Dinosaurs?
	+ Skull display
* Was Pachycephalosaur Really A Headbutter?
	+ Skull display
	+ Stock footage from Swamps
	+ BMR P.2001.4.5

 Main **Segments** Gallery

MainSegmentsGallery

These are Prehistoric Planet segments which feature ***Pachycephalosaurus***.

## Swamps

**Swamps**, Segment IV
**Setting**
Scollard Formation, southwest Alberta, Canada

**Filming Location**
Lake Morena County Park, San Diego, California

***“ This inland basin in North America was, in the past, several feet deep in water. But after a decade of drought, it's now bone-dry. Nonetheless, some dinosaurs still linger here. ”***

― **David Attenborough**, *Swamps*
The fourth, penultimate segment of Swamps is set in an arid, rocky basin. The region, once several feet deep in water, has been rendered dry by a decade of drought. The wind blows the dust off the long-desiccated bones of a fish that once thrived in the area, now overtaken by beetles and plant life suited to the harsh climate. Even so, some dinosaurs continue to live and endure the challenges of the environment.

***“ A herd of pachycephalosaurs, bizarre creatures with thick, dome-shaped skulls. They prefer to feed on fruit and leaves. But now, they're forced to make do with roots and insects. ”***

― **David Attenborough**, *Swamps*
Running through the parched lands is a herd of ten pachycephalosaurs searching for food and water. While the pachycephalosaurs are stated to prefer fruits and leaves, given the harsh conditions of their habitat, they are forced to subsist on roots and bugs, with the leader, a large male, headbutting a dead tree to the ground in order to feed on the insects within.

***“ The herd is led by a large male. He keeps order, so everyone is able to search for food in peace. But trouble is brewing within the herd... ”***

― **David Attenborough**, *Swamps*
Soon after this, the leader gets up on a rock, with most of the other members assembling around him as he looks around to observe for threats as well as to check on every member in the herd. He then notices a young male making trouble by aggressively ramming another member to assert his dominance. This disrupts the order of the herd, and the young male may eventually gain enough courage and strength to challenge the dominant male's leadership.

***“ The young male is throwing his weight around. It's time for the dominant male to put him in his place, or kick him out. ”***

― **David Attenborough**, *Swamps*
Not willing to let the troublemaker continue on with this behavior, the leader leaps off the rock to confront him and tries to intimidate him by swinging around his massive, vibrantly-colored dome, scars, horns, and all, in order to force him back in his place. Undeterred, the troublemaker does the same, energetically swinging his less-impressive dome, the rest of the herd watching in anticipation as the two males continue to bellow and try to intimidate each other. Eventually, the leader, seeing that there is no real progress being made, loses his patience and rushes head-on at the young challenger, who promptly blocks him with his own dome. The leader recovers more quickly from the collision and knocks the younger male away with a strike to the flank. When he gets rammed in the side by the challenger in retaliation, the leader quickly follows up by trying to crash his head downwards on his enemy, only for the young challenger to block his attack with his own dome again.

***“ The older male is heavier. But the younger is more agile and has more stamina. And that tips the balance in his favor. ”***

― **David Attenborough**, *Swamps*
The fight escalates from there, with the dominant male becoming more offensive, nullifying the challenger's defensive blocks by continuing to push him back whenever their heads collide. Forced to be on the defensive, the younger male rushes off to catch a break, gain more space, and continue from there, while the older male pursues him and attempts to knock him down with a side swipe, eventually tackling his rival into a shallow ditch that appears to be the remnants of a dried-up river, while the other herd members rush around them to continue observing the battle.

Quickly getting up, the two males forego their usual headbutting attacks and begin wrestling like monitor lizards, pressing their bodies and necks against each other to force the other down on the ground. They even attempt to lock the spikes on the back of their heads to gain control and twist each other into submission. The leader, utilizing his superior weight, tries to subdue the troublemaker by pressing down on him. However, the young challenger relies on his agility and stamina to swing his neck at the enemy's neck, successfully knocking him to the ground. Asserting his dominance, the young challenger places his foot on the defeated leader.

Believing that he can now firmly establish himself as the new head of the herd, the young male walks around and triumphantly bellows to the rest of the pachycephalosaurs. However, as the upstart continued to proclaim his victory, the older male, who was not fully incapacitated, suddenly rushed at him and violently rammed into his left flank, catching him off-guard and forcefully knocking him down to the ground, cutting short his premature rise to power.

***“ A bellow of victory... but, too soon. The loser has to pay a heavy price. Exile. Alone, it will be a struggle to fend for himself. But life here will not be easy for the winner either, unless the water returns to this land, and soon. ”***

― **David Attenborough**, *Swamps*
Standing triumphantly over him, the dominant male, along with the rest of the pachycephalosaurs, drives the troublemaker out of the herd, reducing the members from ten to nine. Forced into exile, the young male would find it difficult to fend for himself, though the victorious leader and the remaining members of his herd will also continue to face hardship as long as water does not return to the area. As he watches the banished member run off into the distance, the leader, panting due to exhaustion, walks off to continue the search for sustenance in the impoverished wilderness of their prehistoric world.

## Prehistoric Planet: Uncovered - What Else Lived Alongside The Dinosaurs?

  **What Else Lived Alongside The Dinosaurs?**
**Subject**
The other weird and wonderful creatures that lived alongside the dinosaurs, from *Beelzebufo*, marine reptiles, and pterosaurs, to their successors, mammals.

**Experts**
Dr. Darren Naish, Dr. Marc Jones, Dr. Mark Witton, Professor Anjali Goswami

***“ During the age of the dinosaurs, spectacular species like this Pachycephalosaur attract the most attention. But the prehistoric world was also home to a wide variety of other quite different species. ”***

― **David Attenborough**, *Prehistoric Planet: Uncovered - What Else Lived Alongside The Dinosaurs?*
A *Pachycephalosaurus* skull was briefly shown as part of this Uncovered segment that focuses on the other animals that lived alongside dinosaurs, serving as an example of the sort of spectacular species that tend to attract the most attention whenever the age of the dinosaurs is discussed.

## Prehistoric Planet: Uncovered - Was Pachycephalosaur Really A Headbutter?

  **Was Pachycephalosaur Really A Headbutter?**
**Subject**
The overall function of pachycephalosaur domes as display features and as ramming weapons.

**Experts**
Dr. Susannah Maidment, Professor Paul Barrett
***“ When they first saw these very thick, domed skulls, and these domes could be up to 30 centimeters in thickness, they were thought to be very strong. It was thought that maybe they were using them for headbutting each other in contests over social hierarchy. ”***

― **Professor Paul Barrett**, *Natural History Museum*
Footage from the pachycephalosaur segment is reused in the Uncovered segment following Swamps, where the purpose of pachycephalosaur domes is discussed, for it is believed that they are strong enough to be used for headbutting, like modern-day bighorn sheep, to settle disputes over social hierarchy. Following the slicing of some pachycephalosaur domes, it was then theorized that they were not able to withstand head-on collisions. Marks across the skull indicate a mesh of tiny fibers that are suggested to support brightly-colored skin for display purposes, like attracting a mate.

***“ This new theory seemed to be accepted until 2013, when a new discovery was made. A pachycephalosaur was found with marks showing it had survived multiple injuries to the top of its head. And it wasn't a one-off. ”***

― **David Attenborough**, *Prehistoric Planet: Uncovered - Was Pachycephalosaur Really A Headbutter?*
When the domes of several pachycephalosaur species in various museum collections were studied, they were also found to have had similar injuries in the same place. Virtual models generated by CT scans were subjected to various engineering tests, with the results further supporting the usage of pachycephalosaur domes for headbutting.

***“ What they've shown is that pachycephalosaur domes could actually have withstood an enormous amount of force. The sort of force that goes through American footballers when they hit each other. ”***

― **Dr. Susannah Maidment**, *Natural History Museum*
With this, it is now believed that pachycephalosaurs used their domes as colorful displays and also as formidable weapons to prove which individual is superior.

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## Trivia

### Swamps

* In sharp contrast with the other segments of Swamps, the fourth segment shows no wetland of any sort, instead featuring a dry area that used to be a swamp.
	+ Dr. Darren Naish, Prehistoric Planet's lead consultant, clarified that this was due to the constraints of making the show. In truth, the arid environment depicted in the segment is inappropriate for *Pachycephalosaurus* and the episode as a whole, and *Pachycephalosaurus* was more likely to be found in the low-lying, heavily forested wetlands of North America, much like the environment shown in the fifth and final segment of Swamps.
* This is the eighth segment to feature intraspecific combat, and the fifth one to result in the older individual winning.
	+ Had the young male *Pachycephalosaurus* actually defeated the older male, it would have been the third such segment to result in a victory for the younger animal.
* This segment showcases several ways in which pachycephalosaurs may have used their heads in combat. Headbutting and flank-striking are the most prominent actions, but the leader of the herd, at one point, swings his head sideways like a club while chasing his younger rival down in an attempt to knock him off-balance, and later on, the two combatants grapple with each other by locking the horns on the back of their heads in an attempt to stab each other. The fighting style of the pachycephalosaurs, more up-close and personal as opposed to the more traditional musk oxen style of headbutting, is based on those of lizards like marine iguanas, crocodylians, and even mammals like giraffes.

### Prehistoric Planet: Uncovered - Was Pachycephalosaur Really A Headbutter?

* This Uncovered segment shows a diagram with four different views of specimen BMR P2001.4.5, a *Pachycephalosaurus* dome bearing as many as 23 head lesions.

## References

### General

1. ↑ 1.0 1.1 Cranial Pathologies in a Specimen of *Pachycephalosaurus*
2. ↑ 2.0 2.1 Distributions of Cranial Pathologies Provide Evidence for Head-Butting in Dome-Headed Dinosaurs (Pachycephalosauridae)

### Dr. Darren Naish

1. ↑ *Pachycephalosaurus* should have been featured in well-watered, densely forested lowlands, and its habitat as portrayed on Prehistoric Planet is inappropriate, having resulted from the constraints of making the show.
2. ↑ Pachycephalosaurs did not butt heads like musk oxen, though numerous skull injuries indicate that they did bash heads, just in a manner different from traditional portrayals. They would have fought up-close, pushing, shoving, swinging their heads, and even using their spikes to stab, with the show basing their fighting styles off of lizards like marine iguanas, crocodylians, and even mammals like giraffes.

### Prehistoric Planet

1. ↑ 1.0 1.1 I Know Dino: The Big Dinosaur Podcast, Episode 445: Dinosaurs in Swamps: Featuring Prehistoric Planet 2