Edmontosaurus

## EdmontosaurusEdmonton Lizard

* Male
* Female
* Juvenile

### Temporal Range

73 - 66 million years ago, Campanian - Maastrichtian Stage, Late Cretaceous Period

### Episodes

* Ice Worlds (Segments 1 and 2)
* Forests (Segment 5)
* Swamps (Segment 5)

## Characteristics

### Weight

5.6 - 7 metric tons (6.2 - 7.7 short tons)

### Diet

Herbivore

**Speed** of 25 - 30 kilometers (15.5 - 19) per hour

 **Main** Segments Gallery

MainSegmentsGallery

***Edmontosaurus*** (Edmonton Lizard) is a genus of saurolophine hadrosaurid dinosaur that lived in western North America 73 - 66 million years ago, from the Campanian to the Maastrichtian stage of the Late Cretaceous Period. Next to *Triceratops*, it is one of the most common dinosaurs of its place and time.

## Description

### Size and Physique

As a hadrosaur, *Edmontosaurus* was heavily-built, with a long, laterally flattened tail and duck-like beak. As one of the largest hadrosaurs ever discovered, *Edmontosaurus* measured around 11 - 13 meters (36 - 42 feet) in length, and weighed around 5.6 - 7 metric tons (6.2 - 7.7 short tons) according to a study in 2022. Some remains indicate that *Edmontosaurus* could have reached sizes similar to that of its larger Chinese relative, *Shantungosaurus*, which is the biggest non-sauropod dinosaur ever known, reaching lengths of 15 - 16.6 meters (50 - 54 feet) and weights of 13 - 16 metric tons (14 - 18 short tons), though it is believed that these were exceptional, rare cases as opposed to being an indication of the animal's large size.

### Speed

***“ A group of Edmontosaurs. They lack armor, but they're as big as T. rex, and twice as fast. To catch one needs cunning. ”***

― **David Attenborough**, *Swamps*
Despite its bulky physique, Prehistoric Planet states that *Edmontosaurus* can be twice as fast as *T. rex*. In 2009, studies indicate that *Edmontosaurus* can reach a speed of 15.7 meters (52 feet) per second, or 57 kilometers (35 miles) per hour, when galloping on all fours, and 14 meters (46 feet) per second, or 50 kilometers (31 miles) per hour, when running on two legs. By comparison, a 2017 study indicates that *T. rex* could only run up to 27 kilometers (17 miles) per hour, and it would likely exhaust itself before reaching its top speed, though a study in 2021 also calculated a rhythmic, energy-efficient walking speed of 1.28 meters (4 feet, 2 inches) per second, or 4.6 kilometers (3 miles) per hour for *T. rex*.

However, Dr. Darren Naish later clarified that the idea of *Edmontosaurus* being twice as fast as *T. rex* was an error, and both animals actually had a similar top speed, meaning that, given the modern estimates of the maximum speed of *T. rex* (which was calculated almost a decade after the studies regarding the running speed of *Edmontosaurus*, and thus, are more in-line with the current understanding of these animals), *Edmontosaurus* likely also ran at speeds of around 25 - 30 kilometers (15.5 - 19 miles) per hour, making it easier for a *T. rex* to catch up to one of these hadrosaurs (though ambushing prey is still more preferable for predators since it would help conserve effort, energy, and time).

### Prehistoric Planet's Depiction

*Main: Edmontosaurus on Prehistoric Planet*

Main: Edmontosaurus on Prehistoric Planet

On Prehistoric Planet, *Edmontosaurus* is depicted as being mostly brown with a white underside that travels upwards in vertical stripes, providing the hadrosaur with countershading to help enhance camouflage. *Edmontosaurus* is known to come in various lightly-built and robust forms, though it is unknown if this is meant to indicate sexual dimorphism. Instead, the show depicts the adult males as being mostly the same as the adult females, save for their bright green and yellow markings on the face and neck area. The show doesn't appear to indicate any significant difference between *Edmontosaurus regalis* of Horseshoe Canyon Formation (fifth segment of Forests), *Edmontosaurus annectens* of the Hell Creek Formation (fifth segment of Swamps), or the species (previously classified as a distinct genus known as *Ugrunaaluk*) from the Prince Creek Formation (first and second segments of Ice Worlds).

The Prince Creek species of *Edmontosaurus* (previously classified as a distinct genus known as *Ugrunaaluk*) was featured in the first segment of Ice Worlds trying to cross an icy river while being harassed by dromaeosaurs, with two of the hadrosaurs appearing briefly in the second segment of Ice Worlds, walking down a river while an *Ornithomimus* tries to keep them away from his nest. The fifth segment of Forests shows the Horseshoe Canyon Formation on fire, with an *Edmontosaurus regalis* escaping the flames with her two young. *Edmontosaurus annectens* appears in the fifth and final segment of Swamps, with a herd being attracted to the lush wetlands of the Hell Creek Formation, though they themselves were viewed as food by two subadult *Tyrannosaurus* brothers, which successfully ambush and bring down one of the hadrosaurs while they were grazing through a forest at night. Notably, Prehistoric Planet does not give any distinct features to differentiate these three species known from separate regions of North America.

## Habitat

*Main: Horseshoe Canyon Formation, Hell Creek Formation, Prince Creek Formation*

Main: Horseshoe Canyon Formation, Hell Creek Formation, Prince Creek Formation

***“ Across this vast continent, there are over a hundred thousand square miles of swamplands. And most of them remain flooded all year-round. Here, in spring, new plant growth creates excellent feeding grounds for the gathering herds. ”***

― **David Attenborough**, *Swamps*
*Edmontosaurus* lived 73 - 66 million years ago in Laramidia, an island continent that would one day become western North America, which, by that time, was split in half by an inland sea. It is known from places as far north as Alaska and Canada, though it also lived in more southern areas. *Edmontosaurus* appears to prefer subtropical inland forests, swamps, and rivers (as seen in the Hell Creek Formation, which, though warmer than Montana and South Dakota today, was kept humid by sufficient levels of rainfall), and, like some animals today, is believed to move depending on resources (this does not necessarily mean that they are migratory animals, periodically moving in response to seasonal changes and conditions).

## Behavior

### Social and Parental Habits

Several bonebeds indicate that *Edmontosaurus* lived in large herds (said to be headed by several leaders on the show, though it is also possible that this implies that several herds, each with a single leader, combined to form a larger head for this occasion). However, it is also possible that some individuals were solitary, or, as shown in Forests, only lived with their offspring or other family members. Herding behavior allows for safety in numbers, though this comes at the expense of the few that are focused on and attacked while the rest get away from the threat.

Prehistoric Planet also depicts female *Edmontosauruses* as caring for their young, with one mother urging her calf out of a river in Ice Worlds (though she doesn't actually help it), and another carefully guiding her two offspring out of the burning woods in Forests. Even so, Dr. Darren Naish, Prehistoric Planet's lead consultant, brings up how *Edmontosaurus* likely laid 20 - 30 eggs like most dinosaurs, hence, they live by the r-selection strategy, since they have many offspring, many of which are not expected to survive up to adulthood, a fact that some predators may take advantage of, as shown when a pack of dromaeosaurs harass an *Edmontosaurus* herd by a river crossing with the knowledge that some won't survive raging rapids.

### Traveling Habits

***“ These duckbilled dinosaurs pass through here every year, nomads in search of the fresh vegetation brought by the spring. Their huge. The only chance the dromaeosaurs will have is to work as a team. ”***

― **David Attenborough**, *Ice Worlds*
Some studies support the idea that *Edmontosaurus* was a migratory animal, stocking up on fat and other energy resources to make a 2,600-kilometer (1,600-mile) round trip every year, which would require a pace of 2 - 10 kilometers (1 - 6 miles) per hour, and could explain the animal's presence in Alaska and Canada. Other studies, however, conclude that *Edmontosaurus* did not migrate and simply endured wintertime.

As clarified by Dr. Darren Naish, several lines of evidence suggest that the *Edmontosauruses* of the far north were actually not migratory, with one form of proof being babies in the north of Alaska. Hence, Prehistoric Planet simply refers to them as "nomads", constantly moving to where food is plentiful. Regardless, due to this sort of lifestyle, *Edmontosauruses* would have faced several dangers on their journey, from predators to the environmental terrain and conditions.

### Defensive Tactics

*Edmontosaurus* is roughly just as fast as its main predator, *Tyrannosaurus rex.* Hence, when confronted with threats, the hadrosaurs prefer to flee. In response, predators tend to use different tactics to bypass or even exploit their tendency to run from danger. In Ice Worlds, dromaeosaurs several times smaller than them successfully get the whole herd to panic, stampede, and frantically try to cross an icy river even though they are no threat to adults, and are only trying to harass the juveniles, exploiting the pandemonium to indirectly get a few of them killed by the river. In Swamps, a pair of *T. rexes* hunt in the darkness of the night, also cause panic to a degree, and ambush their prey, forcing a single targeted *Edmontosaurus* into a position where the pair can close in on it and kill it.

Even so, given its size, *Edmontosaurus* is not defenseless. Despite lacking armor or visible weapons of any kind, these large animals are capable of enduring a few of the bone-crushing bites of a *T. rex*, as indicated by DMNH-1943, a specimen with a damaged hip and a U-shaped notch on its tail that fits the shape of a *T. rex's jaws*, indicating that it survived and escaped a *T. rex* attack. The original plan for the fifth segment of Swamps even involved two juvenile *T. rexes* attacking an adult *Edmontosaurus*, only to be beaten up. While this particular idea ultimately never came to pass, the final version of events showed that it still takes a considerable amount of experience, skill, and even luck for a *T. rex* to bring down an *Edmontosaurus*.

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## References

### General

1. ↑ 1.0 1.1 1.2 Osteohistological and taphonomic life-history assessment of *Edmontosaurus annectens* (Ornithischia: Hadrosauridae) from the Late Cretaceous (Maastrichtian) Ruth Mason dinosaur quarry, South Dakota, United States, with implication for ontogenetic segregation between juvenile and adult hadrosaurids
2. ↑ 2.0 2.1 Why *Tyrannosaurus* was a slow runner and why the largest are not always the fastest
3. ↑ Dinosaur Census Reveals Abundant *Tyrannosaurus* and Rare Ontogenetic Stages in the Upper Cretaceous Hell Creek Formation (Maastrichtian), Montana, USA
4. ↑ A juvenile *Edmontosaurus* from the late Maastrichtian (Cretaceous) of North America: Implications for ontogeny and phylogenetic inference in saurolophine dinosaurs
5. ↑ Virtual Palaeontology: Gait Reconstruction of Extinct Vertebrates Using High Performance Computing
6. ↑ Walk the dinosaur: New biomechanical model shows *Tyrannosaurus rex* in a swinging gait
7. ↑ Polar dinosaurs on parade: a review of dinosaur migration
8. ↑ Hadrosaurs Were Perennial Polar Residents
9. ↑ Evidence of predatory behavior by carnivorous dinosaurs

### Dr. Darren Naish

1. ↑ 1.0 1.1 1.2 The idea that *Edmontosaurus* is twice as fast as *T. rex* is a mistake, the narration was instead supposed to state that both animals had a similar top speed.
2. ↑ The fifth segment of Swamps has two subadult *T. rex* brothers hunting together in order to show the idea that dinosaurs of many sorts likely maintained familial social bonds throughout life.
3. ↑ *Edmontosaurus* is an r-strategist, and predators tend to take advantage of this fact.
4. ↑ *Edmontosaurus* (at least the ones that lived in the far north) is not a migratory species. The *Edmontosaurus* herd in Ice Worlds are not migratory animals, but nomads, constantly on the move.
5. ↑ *Edmontosaurus* is far from defenseless. The original plan for the *T. rex* hunt was to show two juvenile *T. rexes* (as opposed to the subadults of the final version) trying to take on an adult *Edmontosaurus*, only to be beaten back, though this particular idea never ended up getting developed.
6. ↑ It still takes a considerable amount of experience, skill, and luck for a *T. rex* to tackle an *Edmontosaurus* and finally subdue it with a bite to the throat.

### Prehistoric Planet

1. ↑ As indicated by the name of the *T. rex* pair's theme in the Official Soundtrack, "Tyrannosaurus Brothers".