Name:
Brachylophosaurus
(Short crested lizard).
Phonetic: Brak-e-loe-foe-sore-us.
Named By: Charles M. Sternberg - 1953.
Synonyms: Brachylophosaurus goodwini.
Classification: Chordata, Reptilia, Dinosauria,
Ornithischia, Ornithopoda, Hadrosauroidea, Hadrosauridae,
Saurolophinae.
Species: B. canadensis
(type).
Diet: Herbivore.
Size: About 9 meters long.
Known locations: Canada, Alberta - Oldman
Formation. USA, Montana - Judith River Formation.
Time period: Campanian of the Cretaceous.
Fossil representation: Several individuals.
The
first Brachylophosaurus remains were discovered in
Alberta in 1936,
but were not named until 1953 when Charles Sternberg made the
description. A second species of Brachylophosaurus
was named as B.
goodwini by Jack Horner in 1988; however the wider
consensus today
is that these individuals are actually further individuals of the genus
type species, B. canadensis. However in a
twist to this,
despite the type species name meaning ‘from Canada’, most
Brachylophosaurus remains at the time of writing
have been found across
the border in the US state of Montana.
Some
of the remains in Montana are of exceptionally well preserved
individuals, some of which are amongst the best hadrosaur
specimens
currently known. The most famous of these discoveries were given the
nicknames ‘Elvis’, ‘Leonardo’, ‘Roberta’ and ‘Peanut’.
‘Leonardo’ in particular has become particularly famous and is known
as the ‘dinosaur mummy’ because the body had been naturally
mummified before being fossilised. Although not the first dinosaur
mummy to ever be discovered, ‘Leonardo’ was a subadult that was
preserved at almost ninety per cent complete, and reveals details
such as muscle positions, builds, tendons, skin pouches and even
a frill than ran down the back. However while the discovery of
Leonardo has helped to confirm and reveal some details about what
hadrosaurs looked like, how the dinosaur came to be mummified is
still not fully explained since it seems to have lived in a wet
environment, and mummification usually only occurs in dry/arid
conditions. It is not impossible that a different form of
preservation preserved the soft tissues before they decomposed,
perhaps in a similar manner to how the soft tissues of some fish such
as the placoderm Eastmanosteus
and the shark Cladoselache
have been
preserved.
As
living dinosaurs, Brachylophosaurus was quite
unique amongst other
hadrosaurs. One identifying feature is the flat crest on top of the
skull, but there seems to be two different versions with some
individuals having crests that were much smaller than others. One
theory to explain this is sexual dimorphism where males presumably had
larger crests than females for display purposes. Further inference of
the enlarged crests is that they may have been used for ‘head
pushing’ contests as opposed to outright ‘butting’, but this
idea is widely accepted, and remains a possible as opposed to a
probable theory. Another noteworthy set of features for
Brachylophosaurus are the fore limbs which are
proportionately longer
than those of most other hadrosaurs. Additionally the upper jaw is
also proportionately wider than other genera.
On
a final note about the biology of Brachylophosaurus,
a 2003 study
by Rothschild et al found that Brachylophosaurus
specimens displayed a
number of tumours. It is impossible to say with certainty what kinds
of tumours these were, but they may have been benign hemangiomas,
bone tumours (desmoplastic fibroma) to even cancerous tumours.
These tumours may also be a sign of Brachylophosaurus
representing an
inbred genus of hadrosaurs which had little genetic diversity within
the population, hence increasing the chance of ailments like tumours
forming. These are backed up by the observation of the majority of
other hadrosaur genera which have little to no signs of tumours.
Likely
shared its habitat with other plant eating dinosaurs such as the
ceratopsian Chasmosaurus
as well as the more famous hadrosaur
Parasaurolophus.
Predatory threats to Brachylophosaurus may have
come from the tyrannosaurs
Daspletosaurus
and Gorgosaurus.
Further reading
- A new hadrosaur from the Oldman Formation of Alberta: Discussion of
nomenclature. - Canadian Department of Resource Development Bulletin.
128: 1–12. - Charles M. Sternberg - 1953.
- New information on the cranium of Brachylophosaurus,
with a revision
of its phylogenetic position. - Journal of Vertebrate Paleontology. 25
(1): 144–156. - Alberto Prieto-Marquez - 2005.
- ‘Leonardo’, a mummified Brachylophosaurus from
the Judith River
Formation. - nate L. Murphy, David Trexler & Mark Thompson -
2006.
- A New Brachylophosaurin Hadrosaur (Dinosauria: Ornithischia) with an
Intermediate Nasal Crest from the Campanian Judith River Formation of
Northcentral Montana. - Plos One. - Elizabeth A. Freedman Fowler
& John R, Horner - 2015.