Edmontonia
Name:
Edmontonia
(From Edomonton - After the Edmonton Formation).
Phonetic: Ed-mon-toe-nee-ah.
Named By: Charles Mortram Sternberg - 1928.
Synonyms: Denversaurus schlessmani,
Palaeoscincus rugosidens.
Classification: Chordata, Reptilia, Dinosauria,
Ornithischia, Thyreophoroidea, Nodosauridae.
Species: E. longiceps (type),
E.
rugosidens, E. schlessmani.
Diet: Herbivore.
Size: 6.6 meters long.
Known locations: Canada, USA.
Time period: Campanian to Maastrichtian of the
Cretaceous.
Fossil representation: Multiple specimens.
Edmontonia
was one of the larger nodasaurids,
dinosaurs that were similar to the
ankylosaurids but lacked their tail clubs and had narrower mouths.
Still, Edmontonia did possess armour plates
called osteoderms
along its back, and is particularly noted for having large spikes
that point out from the sides of its body, the four largest of which
are above the shoulder. It seems unlikely that these spines were just
for defence as they only cover a relatively small part of the body,
and they may not have provided all that much protection against large
theropod dinosaurs such as tyrannosaurs
like Daspletosaurus
and
Albertosaurus.
It’s
plausible that these
shoulder spikes may have been more like deer antlers, with the larger
and more developed spikes belonging to the more mature individuals.
Additionally it is possible that two Edmontonia
may have walked up to
one another and engaged in a pushing contest for dominance, the horns
locking so that the Edmontonia could get a grip of
one another. Again
larger spikes would have been preferable in such a contest as they
would have allowed the more mature individuals a reach advantage.
Study
of other fossils found
in association with Edmontonia, specifically
petrified trees, has
come to the conclusion that Edmontonia lived in an
environment that saw
extended wet and dry periods throughout the year. This would suggest
that like other animals in similar climates, Edmontonia
would lay
eggs to hatch in time for the wet season so that the newly hatched
young had a plentiful supply of fresh vegetation. Additionally the
adults would have spent much of their time feeding upon as many plants
as they could so that they could build up fat reserves to better
survive the lean periods of the dry seasons. The oncoming of the wet
season is also thought to be the reason why some Edmontonia
remains
have the spikes and armour in exactly the same position as they were in
life. This is simply a case of flood water washing a large amount of
sediment over an individual that had died during the dry season,
burying and protecting it from carnivorous animals that may have
scavenged and pulled the body to pieces had it not been buried from
them.
Additional fossil material has been assigned to the Edmontonia genus from other genera. A skull and partial skeleton from Palaeoscincus (originally assigned to the genus as P. rugosidens) was assigned to Edmontonia to create the species E. rugosidens. Additionally another genus, Denversaurus schlessmani, has been declared a synonym to Edmontonia, with the material forming the basis for another new species, E. schlessmani. However the validity of some material belonging to Edmontonia has also been questioned, one case in point being the fossils identified as the species Edmontonia australis now generally considered to belong to the genus Glyptodontopelta. Additionally the palaeontologist Robert T. Bakker proposed in 1988 that the species E. rugosidens should be renamed Chassternbergia and be made a subgenus, although this has not come into common usage by other palaeontologists who still prefer to treat E. rugosidens as a species of the Edmontonia genus.
Further reading
- Edmontonia rugosidens (Gilmore), an armored
dinosaur from the Belly
River Series of Alberta. - University of Toronto Studies, Geology
Series 43: 3-2. - L. S. Russel - 1940.
- Review of the Late Cretaceous nodosauroid Dinosauria: Denversaurus
schlessmani, a new armor-plated dinosaur from the Latest
Cretaceous of
South Dakota, the last survivor of the nodosaurians, with comments on
Stegosaur-Nodosaur relationships. - Hunteria 1(3):1-23.(1988). - R. T.
bakker - 1988.
- Edmontonia - In The Age of Dinosaurs.
Publications International,
LTD. p. 141. ISBN 0-7853-0443-6. - Peter Dodson, Brooks Britt, Kenneth
Carpenter, Catherine A. Forster, David D.Gillette, Mark A. Norell,
& George Olshevsky & Michael J. Parrish & David
B. Weishampel.
- New information on the cranial anatomy of Edmontonia rugosidens
Gilmore, a Late Cretaceous nodosaurid dinosaur from Dinosaur Provincial
Park, Alberta. - Journal of Vertebrate Paleontology. 26 (4): 1011–1013.
- Matthew K. Vickaryous - 2006.
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