Edmontosaurus

Credit: Futaka Kouhei‬.

*Edmontosaurus* is a genus of Hadrosaurid dinosaur that lived in North America during the Late Cretaceous.

## Description

*Edmontosaurus* is generally, a large hadrosaurid dinosaur that was distributed all across North America. This genus is so widespread, with easily over 10,000+ fossils discovered, and only went extinct during the K-PG extinction event.

*Edmontosaurus* has a beak, with about 1,000 small teeth behind its cheeks for turning tough plants to pulp. *Edmontosaurus* has a stocky body, with long forearms with very specialized paws. The paws of *Edmontosaurus*' forelimbs had strange claws. On the third digit bore hoof-like claws, like modern ungulates.

*Edmontosaurus* had a long tail, possibly for rearing up on its hind limbs, and plucking twigs from medium foliage. *Edmontosaurus* had a high spine, with a strange raised vertebrae. The use of such and evolutionary adaptation is unknown.

*Edmontosaurus* may have bore a strange crest on its head in life, or even had an inflatable nasal pouch. *Edmontosaurus* may have made loud bellowing noises to alert others in the herd.

## Notable Specimens

—George F. Sternberg
* AMNH 5060: A mummy of an *Edmontosaurus*, with outstretched limbs, a twisted neck and laying on its back. The specimen was well preserved, and showed skin impressions as well as some organs intact. Scientists attempted to reconstruct the color of the animal, but due to the chemicals applied to boost preservation, they failed.
* NDGS 2000 (prev. MRF-03) "Dakota": This mummy preserves skin, muscle and other soft tissues. The specimen was discovered in 1999 on (young, at the time) Tyler Lyson's family property. The specimen was scouted in 2004 and excavated in summer 2006. Lyson was in highschool at the time of discovery. The full animal was about 12 meters (35 feet) long and weighed about 35 tons. The excavation team, led by Phillip Manning, CT scanned the carcass because of support from NASA and the Boeing Company, producing highly-rendered anatomical images. They found intervertebral discs, alongside muscles and tail tendons, which calculate the animal was 45 kilometers/hour (28 miles per hour), faster than *Tyrannosaurus*. Dakota preserves the paws of *Edmontosaurus* showed that they had hoof-like claws, like modern ungulates. The paper describing the fossil mummy has yet to be released, however. The mummy also preserves pieces of the legs, feet, body and tail. Independent researchers point that Dakota has different-sized scales around it's body, which may represent the individual's colours in life. The body also retains texture in 3D. The mummy was the focus of National Geographic's Dino Autopsy in 2007 . On October 16, 2021, an exhibition named Dakota the DinoMummy was officially revealed at North Dakota Geological Survey's Paleontology Resource Protection Program. It was prepared by Becky Barnes and Mindy Householder.
* CMNFV 8399: The holotype specimen assigned to *Edmontosaurus regalis*, which is now thought to represent a juvenile specimen.
* S.M. R4036: A well preserved mummy housed at the Naturmuseum Senckenberg in Germany.
* "Nancy": Prepared at the Paleontology & Geology Research Lab , Nancy is relatively complete, from the Hell Creek Formation. Some skin impressions exist on the specimen, where pebbly scales dot the skin. The left sclerotic ring was found by a volunteer name Saul between the upper temporal opening of the orbit. A stapes was also recovered. As of 2021, the specimen is fully prepared, sitting in the front window of the preparation lab.

## Paleoecology

The Hell Creek Formation was subtropical, and hot, the environment *Edmontosaurus* was best known to inhabit. *Edmontosaurus* lived right up to the K-PG mass extinction event in the Hell Creek Formation with animals like *Tyrannosaurus* and *Triceratops*. *Edmontosaurus* lived in large herds, and was a large prey item for *Tyrannosaurus* in its time. *Edmontosaurus* is like today's cow, a herd grazer, but also a vulnerable target for hungry carnivores. Large herds of *Edmontosaurus* migrated for the changing seasons, using the advantage of many to deter stalking predators.

## Paleobiology

### Paleopathologies

Out of the many specimens discovered, some sported tumours in their brains. Some of thee brain tumour-related illnesses are; hemangiomas, desmoplastic fibroma, metastatic cancer, and osteoblastoma. The illnesses may have been caused by genetic factors, and only occur in closely related genera. Some specimens also had osteochondrosis, a disease that effects the joints in limbs, but closely resembles tumours. Some individuals had growth stunts, and other diseases.

### Distribution

*Edmontosaurus* lived all across North America during the last few million years of the Cretaceous. Fossil skulls of *Edmontosaurus* have been found as far up as the arctic, meaning many genera have been reclassified, and made synonymous with *Edmontosaurus*.

### Ontogeny

In July of 2014, researchers studied *E. annectens* specimen LACM 23504, which consists of a partial skull and a nearly complete postcranium from the Late Cretaceous Hell Creek of Montana. Most of the postcranial ontogeny occurs in both the pectoral and pelvic girdles, however not in the stylopodia. The authors note that all variation between *Edmontosaurus* life stages may not generalize for all hadrosaurs, constricted to maybe close saurolophines. They also note that factors used to phylogenically inference may not be a product of ontogeny, and immature individuals can be used in phylogenic analysis for saurolophines. The latter may have varying results if the specimen were mature . One nestling specimen from the same location, UCMP 128181. This specimen is fully articulated and consists of a partial scapula, incomplete ribcage, vertebrae spanning from the shoulder midway down the tail, most of the pelvic girdle, both hindlimbs and impressions made from encasing concretions. Tis individual hadrosaur is assigned *Edmontosaurus* due to the prepubic process and the blade of the pubis, and further classified *Edmontosaurus* cf. *annectens*. The specimen has a femur measuring about 148 millimeters. UCMP 128181 allows the hypothesized gait shift from bipedal infants to quadrupedal adults to be tested based on limb proportions and placement. Although forelimbs do not preserve in UCMP 128181, forelimbs from about 25 *E. annectens* reveal an overall isometric pattern relative to hindlimbs, within one-another. These evidence shows that nestling *Edmontosaurus* could fully walk quadrupedally, and supports no evidence towards the proposed bipedal/quadrupedal gait shift during the animals life .

## Synonyms

* *Anatosaurus*
* *Anatotitan*
* *Ugrunaaluk*?
* *Trachodon*
	+ *Diclonius*
* *Thespesius*

## Classification

*Edmontosaurus* classification per Horner et. al., 2004 (top) and Gates and Sampson, 2007 (bottom).

## Gallery

### Reconstructions

**Credit: Chris Masnaghetti.****Credit: Alex Lewko, Chris Masnaghetti, R.J. Palmer and Jake Baardse.**A colour key created by the Saurian team by studying the scales on the *Edmontosaurus* mummy "Dakota".
**Credit: the Saurian team.****Credit: Jagged Fang Designs.****Credit: TroodonVet on DeviantArt.****Credit: Paleop on DeviantArt.**
### Fossils

AMNH 5060 as seen from the back.AMNH 5060 as seen from the face backwards.*E. sp.* caudals from North Slope, Alaska stored at the Perot Museum."Nancy", fully prepared.
### Mounts

*Edmontosaurus* skull at the Royal Tyrrell.
### Diagrams

Drawing of *Edmontosaurus* (*Trachodon*) scales.Hooves as seen on "Dakota".

## References

* https://en.wikipedia.org/wiki/Edmontosaurus
* https://en.wikipedia.org/wiki/Trachodon
* https://en.wikipedia.org/wiki/Ugrunaaluk
* https://en.wikipedia.org/wiki/Edmontosaurus\_mummy\_AMNH\_5060
* https://en.wikipedia.org/wiki/Edmontosaurus\_mummy\_S.M.\_R4036
* https://handwiki.org/wiki/Biology:Edmontosaurus\_kuukpikensis
* https://twitter.com/EJR\_Paleo\_MSc/status/1484405976094629888

1. ↑ https://twitter.com/boydpaleo/status/1449118081314213891
2. ↑ https://royalsocietypublishing.org/doi/abs/10.1098/rspb.2009.0812?rss=1
3. ↑ https://en.wikipedia.org/wiki/Dakota\_(fossil)
4. ↑ https://twitter.com/boydpaleo/status/1448026771035615236
5. ↑ https://twitter.com/boydpaleo/status/1449785059742044163
6. ↑ https://naturalsciencesresearch.wordpress.com/2012/07/09/439/
7. ↑ https://naturalsciencesresearch.wordpress.com/2012/07/12/eyes-and-ears/
8. ↑ https://twitter.com/lisaherzog\_me/status/1448461967354699778
9. ↑ https://www.sciencedirect.com/science/article/abs/pii/S0195667114000950
10. ↑ https://www.tandfonline.com/doi/abs/10.1080/02724634.2017.1398168