Mapusaurus
Name: Mapusaurus
(Earth lizard).
Phonetic: Mah-puh-sore-us.
Named By: Rodolfo Coria & Philip J.
Currie -
2006.
Classification: Chordata, Reptilia, Dinosaria,
Saurischia, Theropoda, Carcharodontosauridae, Giganotosaurinae.
Species: M. roseae (type).
Diet: Carnivore.
Size: Known fossils are from individuals ranging
between 10.2 and 12.6 meters in length, however it is not impossible
that very large Mapusaurus may have been slightly
larger.
Known locations: Argentina - Huincul Formation.
Timeline: Cenomanian of the Cretaceous.
Fossil representation: Remains of up to seven
individuals discovered in a bone bed together.
Closely
related to the massive predator Giganotosaurus,
the discovery of
seven Mapusaurus individuals in the same bone bed
would question the
notion that predatory dinosaurs were always solitary creatures. When
the bone bed was excavated between 1997 and 2001, only the
remains of Mapusaurus where found, and these
individuals were all of
different ages. These are two of the hallmarks that have led to this
bone bed to be hailed as strong evidence to support the pack hunting
predator hypothesis. Further, while it is not known what Mapusaurus
targeted as a prey, it does hail from the same part of the world as
the huge titanosaur
Argentinosaurus.
A full grown individual of this dinosaur
would have been unassailable to just one of the known predators of the
time, but a pack targeting the weaker perhaps not fully grown
individuals would have had a chance of defeating it by attrition
alone. This is of course just conjecture, and without further
fossil finds, this is how this scenario will remain.
Analysis
of the site however
could cast doubt on potential gregarious behaviour as the area has been
interpreted as a depositional area. This means that the bone bed may
have been formed when a stream or river had swollen with flood water,
and carried the Mapusaurus individuals
down-stream and deposited
them in a group arrangement. If true then this would be a great fluke
of nature considering that only Mapusaurus and no
other
dinosaurs species were
washed there.
What
is known about
Mapusaurus is that it is a member of the
Carcharadontosauridae,
a
group known for its large members that can rival and even exceed the
more famous Tyrannosaurus
rex in size. The teeth
on Mapusaurus where
very much like those of its relative Giganotosaurus
in that they were
flat and curved with a serrated edge, perfect for slicing through
flesh. This is in contrast to the teeth which are found in
Tyrannosaurus which are conical and smooth, an
adaption better suited
to biting through bone.
Study
of the teeth has led to
further strengthening of the hypothesis that Mapusaurus
could have
preyed upon dinosaurs like Argentinosaurus that had
bones that were
simply too big to bite through. If the pack hunting theory is true
then Mapusaurus may have worn down an Argentinosaurus
with multiple
bites. These wounds would that lead to blood loss and infection which
would then bring the huge dinosaurs down.
Mapusaurus
is a combination
of the Mapuche word for earth, and the Greek word for lizard. The
species name M. roseae has dual meaning,
references both Rose
Letwin, the dig sponsor, and the colour of the rocks that
Mapusaurus was recovered from.
Further reading
- A new carcharodontosaurid (Dinosauria, Theropoda) from the Upper
Cretaceous of Argentina - Geodiversitas 28(1):71-118 - R. A. Coria
& P. J. Currie - 2006.
- New Information on the Cranial Anatomy of Acrocanthosaurus
atokensis
and Its Implications for the Phylogeny of Allosauroidea (Dinosauria:
Theropoda). - PLoS ONE 6(3): e17932. - Drew R. Eddy & Julia A.
Clarke - 2011.
- Palaeopathological survey of a population of Mapusaurus
(Theropoda:
Carcharodontosauridae) from the Late Cretaceous Huincul Formation,
Argentina - PLoS ONE 8(5):e63409:1-6 - P. R. Bell & R. A. Coria
- 2013.
- Cranial ontogenetic variation in Mapusaurus rosae
(Dinosauria:
Theropoda) and the probable role of heterocrony in carcharodontosaurid
evolution. Palaeontol Z doi: 10.1007/s12542-014-0251-3. - J. L. Canale,
F. E. Novas, L. Salgado & R. A. Coria - 2014.
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