About Edmontosaurus
| Scientific Name (Genus) | Edmontosaurus |
| Meaning of Name |
Edmonton lizard
Named after the Edmonton Formation in Canada |
| Classification | Ornithischia, Ornithopoda (Hadrosauridae, Saurolophinae) |
| Total Length | Approx. 9 - 15m |
| Weight | Approx. 4.0 - 15.9 tons |
| Diet | Herbivorous |
| Period | Late Cretaceous (approx. 73 - 66 million years ago) |
| Sub-classification / Species Name |
Edmontosaurus regalis
(Type species)
Edmontosaurus annectens |
| Year of Paper Publication | 1917 |
| Genus Name Publication |
A new genus and species of crestless hadrosaur from the Edmonton Formation of Alberta.
The Ottawa Naturalist. 31. Lambe, Lawrence M. 1917. |
Features and Giant Body
Edmontosaurus was a herbivorous dinosaur belonging to the Hadrosauridae (duck-billed dinosaurs) family, which widely inhabited the North American continent during the Late Cretaceous period.
It boasted one of the largest sizes in Earth's history for an animal capable of walking on two legs. A standard adult was 9 to 12 meters long and weighed 4 to 5.6 tons. Furthermore, research on recently discovered extra-large fossil specimens suggests that it may have grown to a massive size of over 15 meters in length and approximately 15.9 tons in weight, rivaling even the contemporary Tyrannosaurus.
Studies examining the shape of its brain cast have revealed that it possessed a highly developed sense of smell along with vision. Using these sharp senses, it communicated within giant herds ranging from dozens to thousands of individuals, and could quickly detect approaching carnivorous dinosaurs.
The Amazing Chewing Organ "Dental Battery"
The densely packed dental battery can be observed.
The face of Edmontosaurus is characterized by a flat, duck-like snout. However, recent research has revealed that a large, shovel-like keratinous beak with grooves actually extended more than 8 centimeters further forward than the bone.
At the back of its mouth, it had a sophisticated tooth mechanism called a "dental battery." Hundreds of teeth were densely packed in both the upper and lower jaws, and there were always nearly 1,000 teeth in its entire mouth.
Through a complex movement of sliding its jaws back and forth, it efficiently ground up and ate tough plants such as ferns and conifers. Teeth worn down by eating were continuously replaced by new ones at a fast pace of about 50 to 100 days.
It is a structure where many teeth are densely packed together, acting like a single giant file. Edmontosaurus teeth were cleverly composed of both easily worn parts and hard parts, giving them a "self-sharpening function" where chewing plants naturally ground the surface of the teeth to a rough texture.
Gait and Athletic Ability
Edmontosaurus usually walked leisurely on four legs, but used a "bipedal/quadrupedal gait," standing up and running on its two hind legs when it needed to escape quickly.
According to computer-based walking simulation studies, its speed when running on two legs is calculated to have reached a maximum of 50 kilometers per hour (14 meters per second). This mobility functioned to help it escape from Tyrannosaurus, the apex predator of its time.
Mummy Fossils and the Discovery of "Hooves"
Edmontosaurus is a dinosaur for which multiple "mummy fossils" have been found, where soft tissues such as skin and scales have been fossilized three-dimensionally.
It was covered in tiny scales about 1 to 5 mm in size.
There was a time when the skin on the front feet of a mummy fossil was misinterpreted as "webbing," leading to the belief that "Edmontosaurus was an aquatic animal living near water." However, it has now been proven that they lived entirely on land.
Furthermore, the latest research in 2025 has revealed that the tips of their feet had hard "hooves" very similar to those of mammalian horses. The front foot was mitten-shaped with a single large hoof in the center, and the hind foot supported their weight with strong hooves and large footpads on each of its three toes. This was the first time hooves had been found in a reptile, a discovery that greatly revised our image of how dinosaurs walked.
Normally, the skin and internal organs of a carcass decay and disappear quickly. However, it is thought that when bitten by a crocodile or carnivorous dinosaur, holes were opened in the body, allowing gas and fluids to escape. The skin then stuck to the bones like a deflated balloon and dried rapidly, or fine clay particles adhered to the surface of the carcass, creating a "mold," miraculously preserving the shape of the skin.
Fleshy Crest on the Head
Edmontosaurus was thought to be a dinosaur with no distinctive ornamentation on its bones, but a surprising fact was revealed in 2014 from a mummified fossil of "Edmontosaurus regalis" found in Canada.
There was a "crest made entirely of soft flesh" with no bony core, extending from the top to the back of its head. It was shaped somewhat like a bowler hat, about 30 centimeters long, and closely resembled the comb of a modern rooster.
This conspicuous crest is thought to have been used for communication within the herd, appealing to the opposite sex, or for thermoregulation.
Battles with Tyrannosaurus
Edmontosaurus was a rich food source for large carnivorous dinosaurs like Tyrannosaurus in the North American ecosystem at the end of the Cretaceous period.
In one Edmontosaurus fossil, the tail bone had been bitten off by the powerful jaws of a Tyrannosaurus. There were also traces of healed wounds around the bone. This Edmontosaurus survived despite receiving a fatal attack to its tail.
Traces of an even more gruesome battle were found on another Edmontosaurus skull fossil. The teeth of a Tyrannosaurus were fossilized while deeply embedded in the snout of the Edmontosaurus. Since there are no signs of healing on the bone, it is thought to have been a lethal attack.
Sedentary Life in Freezing Alaska
Large numbers of Edmontosaurus fossils have also been found in the Prince Creek Formation in Alaska, which is close to the Arctic Circle at 80 degrees north latitude. Although Alaska was warmer at the time than it is today, winter brought a harsh environment with complete darkness (polar night) lasting for several months and temperatures dropping below freezing.
Whether they migrated to warmer southern regions before the harsh winter arrived or stayed in the freezing lands had long been a mystery.
However, studies examining cross-sections of bones revealed clear evidence of periodic harsh environmental stress in the bones of the Alaskan population. Fossilized teeth of newly hatched babies, which should not have been able to migrate long distances, have also been found.
From this evidence, it became clear that the Alaskan Edmontosaurus did not migrate south in winter but endured the harsh winter on the spot. This supports the idea that they had the ability to maintain a constant body temperature (endothermy) like mammals and birds.
History of Discovery and Classification
Source: A new genus and species of crestless hadrosaur from the Edmonton Formation of Alberta. The Ottawa Naturalist. 31. Lambe, Lawrence M. 1917.
The history of classifying Edmontosaurus began during the era of intense fossil hunting competition in late 19th-century North America, known as the "Bone Wars," and followed a very complex course.
Initially, fossils discovered in Wyoming were named "Claosaurus." Later, based on fossils discovered in Canada's Horseshoe Canyon Formation in 1912, it was formally named "Edmontosaurus" (Edmonton lizard) by Lawrence Lambe in 1917.
Since then, dinosaurs called by various names such as "Anatosaurus" (duck lizard) and "Anatotitan" appeared, but detailed modern research proved that these were simply "differences in shape due to growth," and they are all now integrated into Edmontosaurus.
Furthermore, fossils discovered in Alaska that were thought to be a different dinosaur called "Ugrunaaluk" are also currently considered to have been young individuals of Edmontosaurus.
Relatively Inexpensive North American Dinosaur
Edmontosaurus is a genus of hadrosaurid with a high volume of excavations. Because of its large yield, it has become a representative North American dinosaur that is relatively inexpensive and available to general fossil collectors. You can sometimes see fossils of jaws, dental batteries (tooth rows), and claws from the Hell Creek Formation in Montana or the Lance Formation in Wyoming, USA, being sold.
Personally, I also own fossils of an Edmontosaurus dental battery and scapula.
Edmontosaurus Stamp and Fossil Gallery
