Saurosuchus
Name:
Saurosuchus
(Lizard crocodile).
Phonetic: Sore-oh-soo-kus.
Named By: Osvaldo Reig - 1959.
Classification: Chordata, Reptilia, Rauisuchia,
Paracrocodylomorpha, Loricata.
Species: S. galilei (type).
Diet: Carnivore.
Size: Usually estimated at 7 meters long,
incomplete remains make this uncertain with a full range of size
estimates being between 6 and 9 meters long.
Known locations: Argentina, San Juan Province -
Ischigualasto Formation.
Time period: Ladinian to Carnian of the Triassic.
Fossil representation: Skull, initially deformed
by fossilisation process. Partial post cranial remains are also known
including, dorsal vertebrae, osteoderms and parts of the pelvis.
Unfortunately
Saurosuchus is only known from incomplete remains,
but those that are
known indicate that it was big. Key to identifying the fossils as
being those of a predator is the skull that has several classic
predatory characteristics. One is the fact that the skull is wider at
the back than at the snout which not only suggests housing for
strong biting muscles but also eyes that were slightly angled forwards
for depth perception. This would allow for easier prey location as
well as timing of strikes so that Saurosuchus could
more successfully
deliver a mortal bite that would result in the death of the prey. The
exact method of execution may have varied according to prey however,
with small animals being killed outright by the teeth and crushing
jaws, while large prey may have been bitten but then allowed to
weaken by bleeding to death before the final kill. The back of the
skull however features attachments for strong neck muscles which might
suggest that Saurosuchus clamped its jaws and held
onto prey as it
struggled, something that would require strong neck muscles to
support the skull so that the prey could not shake itself free.
The
teeth of Saurosuchus are thought to have been
replaced over the course
of its life so that when a tooth became worn and lost, another would
grow in to take its place. This would compensate for tooth loss
caused by overly powerful attacks upon large animals that may have
caused some teeth to be broken as they struggled while being bitten.
Tooth replacement is also seen in modern crocodiles and also existed
in the dinosaurs. Another similarity Saurosuchus
shares with the
crocodiles (as well as phtyosaurs) is that the maxillae and snout
are pitted, although the pitting is not as well developed in
Saurosuchus. These pits are attachment points for
tissues, and the
under developed pits of Saurosuchus suggest that
its skulls soft
tissues were not as strong or specially developed as the later
phytosaurs and crocodiles. Such pitting of the skull is so far not
known in other rauisuchian
however, which might suggest that
Saurosuchus was at a more advanced stage of
development.
Like
other rauisuchians,
Saurosuchus is thought to have
had a quadrupedal
posture in order to support its larger size and weight. While slowing
Saurosuchus down when compared to bipedal reptiles,
it was probably
not a hindrance as there were plenty of reptilian prey animals that
would have been just as slow if not slower. A lower quadrupedal
posture also explains the development of osteoderm armour along its
back. While quadrupedal Saurosuchus would have
been able to climb
onto the back of another, and if two Saurosuchus
came into conflict
over territory or the right to feed from a kill, the armour may have
helped protect Saurosuchus from being bitten on a
critical area like
the spine from another. This would allow for a weaker or more
submissive individual to withdraw from a fight injured but still alive.
Further
remains of teeth and skull fragments from the Chinle Formation of
Arizona were attributed to the genus in 2002, but today these
remains are considered to be too indeterminate for classification.
Unless more complete material is found at a later date, the
geographic distribution of Saurosuchus will remain
restricted to
Argentina.
Being
one of the largest known rauisuchian in the fossil record,
Saurosuchus was the apex predator of its day. Saurosuchus
lived in
an ecosystem that saw the steady rise of the early dinosaurs such
as Eoraptor
and Herrerasaurus.
Saurosuchus was
probably too slow for
active predation of the early dinosaurs, although its larger size
meant that the early dinosaurs would almost certainly have given way to
it rather than risk being its next meal. Saurosuchus
was instead
probably a predator of other large and slower animals such as the
rhynchosaur
Hyperodapedon.
Despites
its large size Saurosuchus may not have been the
largest rauisuchian as
another named Fasolasuchus
has been estimated at being between eight
and ten meters long.
Further reading
- The anatomy of Saurosuchus galilei and the
relationships of the
rauisuchid thecodonts - Bulletin of The Museum of Comparative Zoology
146: 317–362. - W. D. Sill - 1974.
- Redescription of the skull of Saurosuchus galilei
(Archosauria:
Rauisuchidae) - Journal of Vertebrate Paleontology 20 (2): 302–316. -
O. Alcober - 2000.
- Nuevo material postcraneano de Saurosuchus galilei
(Archosauria:
Crurotarsi) del Tri�sico Superior del centro-oeste de Argentina -
Ameghiniana 48 (1): 13–27. - M. J. Trotteyn, J. Desojo, & O.
Alcober - 2011.
----------------------------------------------------------------------------
Random favourites
 |
|
|