Muttaburrasaurus
Name:
Muttaburrasaurus
(Muttaburra lizard).
Phonetic: Mut-tah-buh-rah-sore-us.
Named By: Alan Bartholomai & Ralph. E.
Molnar - 1981.
Classification: Chordata, Reptilia, Dinosauria,
Ornithischia, Ornithopoda, Iguanodontia, Rhabdodontidae.
Species: M. langdoni (type).
Diet: Herbivore.
Size: Usually credited with being around 7
meters long, occasional slightly larger estimates are made.
Known locations: Australia, Queensland -
Mackunda Formation. Possibly also New South Wales - Lightning
Ridge.
Time period: Albian to early Cenomanian of the
Cretaceous.
Fossil representation: Skull and partial post
cranial skeleton for the holotype. Further remains including a second
skull have since been attributed to the genus.
Muttaburrasaurus
is one of the best known dinosaurs to come from Australia, though it
was the inclusion of Muttaburrasaurus in an episode
of the TV series
Walking with Dinosaurs that brought it to the
attention of a
worldwide audience. Muttaburrasaurus is named
after the town
Muttaburra situated in Queensland, Australia where
the holotype
remains were first discovered by Doug Langdon in 1963. Although
much of the dinosaur was there, some of remains had been taken as
souvenirs by the local populace, although many of these were returned
when an amnesty for the missing pieces was set up by the local
authority. When the remains were finally described in 1981, the
type species of Muttaburrasaurus langdoni was
established in honour of
Doug Langdon.
Muttaburrasaurus
was an
igaunodont dinosaur, group of medium sized herbivores that had their
origins back in the Jurassic, whose descendants would become the
hadrosaurs of the late Cretaceous. Although often depicted in a
bipedal (two legged) pose, Muttaburrasaurus
probably spent most
of its time in a quadrupedal (all fours) posture. Aside from such
a posture being more easily able to support the body proportions, the
three middle digits on the ‘hands’ of the forelimbs are joined to
form a weight bearing hoof. This adaptation would greatly assist a
quadrupedal animal, but be pointless in a bipedal one. However,
Muttaburrasaurus could probably still balance and
possibly even walk
on just their hind legs while reaching up for higher growing plants.
This would mostly be possible because of the long tail held stiff by a
network of tendons across the vertebrae that acted as a counterbalance
to the forequarters of the body. The ability to switch between
bipedal and quadrupedal postures as the situation dictated meant that
Muttaburrasaurus could potentially browse upon a
wide variety of plant
types.
An
interesting thing about
Muttaburrasaurus is that the teeth are suited more
towards slicing
rather than grinding like in many of its relatives. This led to early
speculation by Ralph Molnar that Muttaburrasaurus
might have
supplemented its diet with meat, possibly by scavenging, though in
1995 Molnar released a new theory suggesting that the teeth were an
adaptation convergent to ceratopsian dinosaurs (ones like Triceratops
and Styracosaurus
that were especially common to Asia and North
America). Further support for this convergent evolution comes from
the fact that ceratopsians are both distantly yet also more closely
related to dinosaurs like Muttaburrsaurus than most
other (especially
saurischian) types of dinosaurs.
Perhaps
the most distinctive
feature of Muttaburrasaurus is the crest that rises
up from the
anterior (front) portion of the snout, that may or may not have
supported an enlarged mass of soft tissue at this point. This hollow
chamber has been interpreted as being for the inclusion of an enlarged
nasal cavity to help with smell, though most herbivores do not have
to rely upon smell that much when finding food. Another idea that has
been suggested is that the crest may have been a form of resonating
chamber for amplifying the calls of individuals so that they were
louder and carried further over greater distances. More confusion
however comes from the observation that in the two currently known
Muttaburrasaurus skulls, the crest is slightly
different. One
skull (the ‘Dunluce skull) has a shorter nasal crest and is
slightly older than the holotype which raises the possibility that the
crest may have changed in form over this time. Alternatively the
difference may be down to the skulls coming from male and female
individuals which might suggest a more visual display function. A
third alternative is that the second skull may be of a different
species to the Muttaburrasaurus type species
established by the first
skull. Any of these theories and perhaps more than one may one day be
proven to be correct, but right now it is hard to be certain without
the recovery of new Muttaburrasaurus fossils. On
a final note, the
nasal crest of Muttaburrasaurus is similar to that
of another
igaunodontid dinosaur from Mongolia called Altirhinus.
Living
during the Albian
stage Muttaburrasaurus may have come into contact
with sauropods such
as Diamantinasaurus,
Wintonotitan
and Austrosaurus
as well as the
small ornithopod Atlascopcosaurus
while pterosaurs
such as Mythunga
and
Aussiedraco
soared through the air on their way to the Eromanga Sea.
Additionally Muttaburrasaurus may have been hunted
by theropod
dinosaurs similar to Australovenator,
though so far this specific
genus is dated to the earlier Aptian period of the Cretaceous.
Further reading
- Muttaburrasaurus, a new iguanodontid (Ornithischia: Ornithopoda)
dinosaur from the Lower Cretaceous of Queensland. - Memoirs of the
Queensland Museum 20(2):319-349. - A. Bartholomai & R. E.
Molnar - 1981.
- Possible convergence in the jaw mechanisms of ceratopians and
Muttaburrasaurus Ralph E. Molnar - In Sixth Symposium on Mesozoic
Terrestrial Ecosystems and Biota, short papers. Beijing: China Ocean
Press. pp. 115–117. - A. Sun & Y. Wang (eds).
- Observations on the Australian ornithopod dinosaur, Muttaburrasaurus.
- Memoirs of the Queensland Museum. 39 (3): 639–652. - Ralph E. Molnar
- 1996.
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