Pachyrhinosaurus/Segments

## PachyrhinosaurusThick-nosed Lizard

Pachyrhinosaurus herd standing off against a pack of Nanuqsaurus in the sixth segment of Ice Worlds

## Presence

* Ice Worlds (Segment 6)
	+ 21 adults
	+ 3 juveniles
* Did Dinosaurs Hunt in Packs?
	+ Stock footage from Ice Worlds

 Main **Segments** Gallery

MainSegmentsGallery

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

## Ice Worlds

  **Ice Worlds**, Segment VI
**Setting**
Prince Creek Formation, Alaska, USA

In the sixth and final segment of Ice Worlds, as the coldest months begun to take hold of the Arctic, a herd of *Pachyrhinosaurus* forages through the forest, feeding on what little food they can find in the snow. Even though their autumn rut is over, two less-dominant males clash heads in order to establish which one is superior. Almost immediately, both are confronted and driven away by an old bull *Pachyrhinosaurus*. The old bull proceeds to scratch his left flank on a tree, and, as he turns to move somewhere else, it is revealed that he has a raw, open wound on his right leg (likely due to constant conflicts).

***“ Battling males barely have time to eat or rest. With food now scarce, it's hard to rebuild strength, and injuries take longer to heal. To make matters worse, the Arctic's most powerful predator is always on the prowl... ”***

― **David Attenborough**, *Ice Worlds*
Just then, a pair of *Nanuqsaurus* emerge from behind the trees, with a third coming from another side of the forest shortly after. Rather than try to ambush a member of the herd, the tyrannosaurs seem to choose playing the long, strategic game. Walking menacingly towards the herbivores, the ceratopsians, fearing the threat of isolation (which would make them easier targets for predators), retreat to an open area, where they can take up a better defensive position.

The herd, consisting of 21 adults and 3 juveniles, form an impenetrable circle, bellowing at the predators as they try to look for a way to attack. At times, when a tyrannosaur gets too close, one of the ceratopsians would charge out of the circle to knock them down, forcing the *Nanuqsaurus* to temporarily retreat. As the blizzard worsens and the herbivores get more disoriented, the *Nanuqsauruses* continue testing for weakness, even as the *Pachyrhinosauruses* continue to charge at them whenever they get too close. Once the blizzard has become too severe, both sides of the standoff hunker down and rest. But when the blizzard has passed, the conflict resumes. While the *Nanuqsauruses* come in from one side of the circle, one *Pachyrhinosaurus* on the opposite side of the circle begins running, prompting the rest of the herd to panic and rush away as well, the tyrannosaurs in hot pursuit.

***“ As the chase goes on, one tiring bull fails to keep up with the rest, until all he can do is turn and face his attackers. ”***

― **David Attenborough**, *Ice Worlds*
One tiring bull, lagging behind the rest, is left behind. Ironically, it is the same dominant male from earlier, as made clear by the chipped-off tip of his right frill horn, the notch in the horn arrangement of the right edge of his frill, and the scar on his back right leg. It appears that, with the life he lead, he has inevitably doomed himself to such a moment. With no other option, he turns and faces his attackers, the trio of tyrannosaurs closing in on him.

***“ One Pachyrhinosaur has lost a battle. But the war will go on all winter. The animals here now face months of total darkness before the sun returns and brings relief to the extraordinary creatures in the world of ice. ”***

― **David Attenborough**, *Ice Worlds*
In the struggle, the bull is dragged down to the ground, pinned, and killed. Two female *Pachyrhinosauruses* stay behind for a while and watch as the *Nanuqsaurus* pack feasts on the once-dominant bull, giving out one last bellow before leaving to rejoin the rest of the herd.

## Prehistoric Planet: Uncovered - Did Dinosaurs Hunt in Packs?

  **Did Dinosaurs Hunt in Packs?**
**Subject**
The plausibility of dinosaurs (even large tyrannosaurs) engaging in pack-hunting.

**Experts**
Dr. Susannah Maidment, Dr. Darren Naish
Footage of *Nanuqsaurus* and *Pachyrhinosaurus* from the final segment of Ice Worlds is used in this Uncovered segment, which discusses the possibility of pack hunting in dinosaurs. During the segment, the topic of bonebeds is brought up, though this is more about tyrannosaur pack hunting than *Pachyrhinosaurus* herding. The segment is mostly focused on how plausible is it for tyrannosaurs (or any carnivorous dinosaur in general) to cooperate, forms packs, and take down large, formidable prey like *Pachyrhinosaurus* together.

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Female *Pachyrhinosaurus**Pachyrhinosaurus* eatingOld Bull scratching the treeThe *Pachyrhinosaurus* herd moves to the open ground
## Trivia

* The sixth segment of Ice Worlds is the fifth segment to feature intraspecific combat. It is the only one so far that did not result in either of the involved individuals winning, as both combatants were confronted, driven away, and forced back in their place by an older male.
* Despite *Nanuqsaurus* being depicted at two-thirds of its actual length in the sixth segment of Ice Worlds (which can be justified by the idea that the three of them might be adolescents), there is evidence that even young tyrannosaurs are capable of attacking fully-grown ceratopsians successfully. One of the most significant fossils of any dinosaur is the "Dueling Dinosaurs" specimen of Hell Creek, which preserves an adolescent *T. rex* locked in combat with a *Triceratops horridus*, proving that even adolescent tyrannosaurs are capable of taking down large ceratopsians, a feat that has more chances of success when done by a pack.

## References

1. ↑ 'Dueling Dinosaurs' fossil, hidden from science for 14 years, could finally reveal its secrets
2. ↑ North Carolina Museum of Natural Sciences to receive the "Dueling Dinosaurs"