Name:
Suchomimus
(Crocodile mimic).
Phonetic: Su-ko-mie-mus.
Named By: Paul Sereno et al. - 1998.
Synonyms: Baryonyx tenerensis.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Theropoda, Spinosauridae, Baryonychinae.
Species: S. tenerensis
(type).
Diet: Piscivore/Carnivore.
Size: About 10 meters long for the holotype, though
fully grown adults were likely larger.
Known locations: Niger - Elhraz Formation.
Time period: Aptian of the Cretaceous.
Fossil representation: Skull and partial skeleton of
what is thought to be a subadult.
The
discovery of Suchomimus helped towards the more
accurate reconstruction
of its potentially much larger relative Spinosaurus.
Combined with
knowledge from the discovery of Baryonyx
and new partial skull
material attributed to Spinosaurus remains resulted
in Spinosaurus
finally being given a crocodile-like skull instead that of the more
typical theropod skull style. These discoveries combined to help
establish a whole new group of theropod dinosaurs, the spinosaurids.
Because
the spinosaurids are a newer group there is still much to learn about
them, especially given the often poor nature of their fossils.
Suchomimus itself seems to be somewhere between Baryonyx
and
Spinosaurus in that it is larger than the former and
smaller than the
latter, and also displays the development of tall neural spines along
its dorsal vertebrae. In Spinosaurus these neural
spines are even
larger, a feature that gave rise to its name which translates as
'Spine lizard'. Baryonyx however does not
display any special
elongation to the neural spines, the key reason why it is regarded as
a separate genus.
However
this reason has been called into question on the principal that the
Baryonyx holotype was not a full grown individual. Suchomimus
itself
was not full grown but still a subadult thought to have been near its
maximum adult size. This has caused many palaeontologists to
contemplate the possibility that both Baryonyx
and Suchomimus are
actually the same genus of dinosaur and that the neural spines did not
begin to grow until the individual approached adulthood. Currently it
is by no means certain that the two are synonymous, but if ever
discovered, fossil material for a near identical spinosaurid of a
size between the sizes of the Baryonyx and Suchomimus
holotypes that
shows an intermediate development of the neural spines, would throw a
lot of weight in support of the synonym theory.
As
a living animal, Suchomimus probably lived the
lifestyle that has
been speculated for all other spinosaurids. This meant that it
probably roamed the semi aquatic environments such as river deltas and
lagoons of early Cretaceous Africa while specifically looking for
fish. This fish specialisation can be clearly seen in the long snout
and lower jaw that contains many long, yet comparatively thin teeth
that are better suited for seizing slippery prey like fish. The
premaxilla also exhibits a rounded notch that fits with the rounded
growth of the lower jaw, a feature that further enhances prey capture.
Suchomimus
probably did not rely exclusively upon fish for its diet and fossil
evidence for spinosaurids suggests that they were opportunists that fed
upon dinosaurs as well as pterosaurs. However what is not known is if
they actually hunted dinosaurs or scavenged the remains of already dead
animals. The fact that the teeth were adapted for catching prey
rather than killing it, may suggest that Suchomimus
had a greater
reliance upon scavenging. It also needs to be remembered however
that Suchomimus had enlarged claws on its hands,
a feature so far
thought to be common amongst spinosaurids due to their association with
spinosaurid remains. With this in mind, Suchomimus
may have been
able to grip smaller ornithopod dinosaurs like Ouranosaurus
with its
mouth while slashing at the neck with its enlarged claws.
The
enlarged neural spines along the back of Suchomimus
were obviously
there for a purpose, with the two most common suggestions being for
the support of either a skin sail or a hump. This debate currently
also exists for Spinosaurus with theories ranging
from
thermoregulation to display to food storage (the latter more for the
hump theory). The robust nature of the neural spines lends more
weight to the hump theory as they seem to be unnecessarily large for
supporting a skin sail. This growth may have been more similar to
that of Acrocanthosaurus
than Spinosaurus itself.
The
overall body plan of Suchomimus may have been
similar to the form of
the South American spinosaurids like Irritator. South American
Spinosaurids are so far mostly known from partial skulls and associated
teeth and vertebrae. During the Early Cretaceous South America and
Africa had split but were still much closer to one another, and
fossil evidence of similar dinosaurs from both continents suggests that
land bridges would have existed to allow new species to cross over,
at least until the early Cretaceous.
Further reading
- A long-snouted predatory dinosaur from Africa and the evolution of
spinosaurids. - Science 282:1298-1302. - P. C. Sereno, A. L. Beck, D.
B. Dutheil, B. Gado, H. C. E. Larsson, G. H. Lyon, J. D. Marcot, O. W.
M. Rauhut, R. W. Sadleir, C. A. Sidor, D. D. Varricchio, G. P. Wilson
& J. A. Wilson - 1998.
- The furcula in Suchomimus tenerensis and Tyrannosaurus
rex
(Dinosauria: Theropoda: Tetanurae). - Journal of Paleontology 81 (6):
1523–1527. - Christine Lipkin, Paul C. Sereno & John R. Horner
- 2007.