Edmontonia is an extinct genus of nodosaur that lived in Canada during the Late Cretaceous.
Description[]
Edmontonia is a bulky nodosaur known from many fossils and a single well-preserved mummy representing the genus. Edmontonia was adorned with many osteoderms. The lower back/upper neck has large plat-like osteoderms in rows. Just above the fore legs are around four spikes, reaching their largest sizes in the center, with smaller sizes on the outside. The middle back is littered with medium/small osteoderms in long rows along the back and tail. Edmontonia had a flat beak, which is designed for snipping tough foliage from the undergrowth. Edmontonia did not have a tail club like popular ankylosaurs, like Ankylosaurus and Euoplocephalus. Edmontonia's skull is relatively boxy, and shaped like a pear. Edmontonia is generally distinguished from similar genera due to minor skeletal differences, and osteoderm orientation.
Classification[]
Chassternbergia, an extremely likely synonym, was once considered a subgenus of Edmontonia. In 1971, Walter Coombs referred to Edmontonia as a subgenus of Panoplosaurus. Little evidence supports this theory.
Paleoecology[]
Edmontonia lived in the Edmonton Formation, hence the etymology, which is now known as the Horseshoe Canyon Formation. The rock formation shows evidence of seasonal shifts of precipitation and temperature, which may be a reason why some of the areas fossils are exceptionally preserved. The Edmontonia mummy may have died, dried out and been covered quickly in sediment as the rain season begun.

Credit: Sphenaphinae on the Wikimedia Commons.
Edmontonia also lived in the Dinosaur Park Formation, a rich habitat during the Late Cretaceous Alberta. Several animals Edmontonia lived with include: Edmontosaurus, Saurolophus and Hypacrosaurus, a variety of freshwater and saltwater fishes and reptiles, troodontids, pachycephalosaurs, other ankylosaurs, dromaeosaurs, caenagnathids, ceratopsians and ornithomimids. Edmontonia was likely a low-browser, plucking plants from the ground. Edmontonia may have defended itself by charging into its predators, and hitting them with its tail, impaling the animal and leaving deep puncture wounds. The Horsheshoe Canyon Formation was ruled by mature Albertosaurus, with smaller niches filled with juvenile individuals.
Notable Specimens[]
- AMNH 5665: A mounted skeleton, preserving fine scale detail and osteoderm placement on the back of Edmontonia. The skeleton consists of a partially-preserved front half.
- AMNH 5381: A well preserved mummy, consisting of a skull, neck, and lower back. The mummy shows the position of the osteoderms in life, as well as the scales. In 1922, the mummy was described as Palaeoscincus by Matthew.
- NMC 8531: The holotype of Edmontonia consisting of a skull, lower jaw, and several elements of the postcranial skeleton.