Name:
Carcharodontosaurus
(Shark toothed lizard).
Phonetic: Car-kah-roe-don-to sore-us.
Named By: Ernst Stromer - 1931.
Synonyms: Megalosaurus africanus,
Megalosaurus saharicus.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Theropoda, Carcharodontosauridae,
Carcharodontosaurinae.
Species: C. saharicus
(type). C.
iguidensis.
Diet: Carnivore.
Size: Estimated between 12 and 13 meters
long.
Known locations: Algeria - Continental Intercalaire
Formation, Brazil - Alc�ntara Formation?, Egypt - Bahar�je Formation,
Mut Formation, Morocco - Aoufous Formation, Kem Kem Formation, Niger -
Continental Intercalaire Formation, Echkar Formation, Elrhaz Formation,
and Tunisia - Chenini Formation, Continental Intercalaire Formation.
Time period: Albian to Cenomanian of the Cretaceous.
Fossil representation: Initial remains destroyed in
world war two, further material including enough to name a second
species has since been found.
The
name Carcharodontosaurus is derived from the Carcharodon
genus of
sharks, a group famous for including the great white shark
(Carcharodon carcharias). This name was chosen
because the teeth
are sharp and serrated in a similar manner to the great white sharks,
something that meant they could slice through the flesh of prey like
sharp knives. These teeth were key to the hunting strategy of
Carcharodontosaurus because when these teeth are
arranged in a mouth
the size that Carcharodontosaurus had, they would
create a massive
open wound. It is this wound that would effectively incapacitate the
prey as blood loss would be so great that shock would quickly set in.
This would cause the prey to become lethargic and disorientated
allowing Carcharodontosaurus to easily close in and
finish it off.
Although
Carcharodontosaurus was named as its own genus by
Ernst Stromer in
1931, it was actually known to science four years earlier, however
when it was first described in 1927 it was described as a species
of Megalosaurus.
Although Megalosaurus
is still one of the best known
dinosaur names today, back in the early days of palaeontology it and
many others where used as ‘wastebasket taxons’ where material was
assigned upon the grounds of superficial similarity.
Even
back then it was clear that Carcharodontosaurus was
most probably
slightly bigger than Tyrannosaurus,
the dinosaur that was hailed as
the biggest meat eater for the best part of a century. The main
reason for the relative obscurity of Carcharodontosaurus
throughout
most of the twentieth century is that its only remains were destroyed
in an allied bombing raid on Munich in world war two, an event that
destroyed other fossils such as the first Spinosaurus
remains, and
the skull of the giant crocodile
Stomatosuchus.
Interest
began to rise in Carcharodontosaurus in the mid
1990s with the
discovery of new Carcharodontosaurus material
resulting in the naming
of the second species C. iguidensis in 2007.
Also another
dinosaur named Sigilmassasaurus brevicollis was
suggested as a junior
synonym by Paul Sereno et al. in 1998 based
upon strong
similarities between it and Carcharodontosaurus.
However a study in
2005 by Novas et al. has cast doubts upon this
claim pointing out
several differences between the associated Sigilmassasaurus
material
and that of Carcharodontosaurus.
Even
if Sigilmassasaurus is confirmed to be its own
genus, the new fossil
material of Carcharodontosaurus is enough to once
again reconstruct
this ancient predator as well as confirm its slightly larger size than
Tyrannosaurus. The resurge of interest in Carcharodontosaurus
can
still be seen today with its almost mandatory inclusion in dinosaur
books, appearances in video games and increasing appearances in
dinosaur documentaries such as the BBC series Planet
Dinosaur.
The
discovery of new fossil material allowed for detailed studies into the
brain of Carcharodontosaurus and how it may have
lived and hunted.
Carcharodontosaurus is often referenced as having a
much smaller brain
than Tyrannosaurus even though it is slightly
larger, leading to the
ungracious statement that it was much ‘stupider’. Such a
statement is a grave misnomer however, as brain size itself is not as
important as the development of individual parts of the brain such as
senses, memory and reasoning. For example an animal with greatly
enlarged sensory areas such as smell and vision would have a larger
brain than another animal that was not as well adapted, but was still
no more intelligent because the brain tissue for these areas do not
make an animal better at thinking about problem solving, just better
able to detect things.
The
brain of Carcharodontosaurus exhibits features that
hail back to the
early archosaurs with similarities being seen in other reptiles such as
crocodiles and turtles. The real interesting thing however is that
the brain layout of Carcharodontosaurus is
different to those of
birds, and this reveals a growing evolutionary trend in dinosaurs
that Carcharodontosaurus was not part of. The
smaller brain size of
Carcharodontosaurus was probably pre-determined by
its archosaurian
ancestry as many theropods of its ancestral line also have similar
brain sizes meaning that while their bodies grew bigger, the brains
stayed the same bringing a halt to further biological development.
The coelurosaurian dinosaurs however, the lineage that would include
Tyrannosaurus and the transitional line to birds
developed their brains
away from the older archosaurian form allowing for the potential of
greater reasoning. This could be part of the reason why predators
along the Carcharodontosaurid lineage would eventually disappear before
the end of the Cretaceous when the new forms were more dominant.
Predators
rely greatly upon their sense of smell for tracking prey over
distances, although it is also probable that Carcharodontosaurus
fed
from carcasses of already dead dinosaurs when it was fortunate enough
to find such an easy meal. When it came to killing its own prey
Carcharodontosaurus seems to have been a primarily
visually orientated
predator (evidence by a large optic nerve), relying upon
stereoscopic vision to provide depth perception to allow it to gauge
distances between itself and prey.
Carcharodontosaurus
is often falsely dubbed the ‘African T-rex’, something which has
misled many people into thinking that they are the same. Really
though the only similarities that they share are that they are both
dinosaurs, and both theropods, and with this analogy you may as
well
call Carcharodontosaurus the ‘African
Velociraptor’,
it would be
no more true or false than calling it the ‘African T-rex’. The
difference between Carcharodontosaurus and
Tyrannosaurus is immediately
clear by looking at just the teeth. Carcharodontosaurus
has laterally
compressed (flattened) teeth that slice through flesh.
Tyrannosaurus in contrast has round conical teeth
for crushing bone.
Include other differences such as size and shape of the skull and
overall body proportions, and it is clear that the two are completely
unrelated.
Carcharodontosaurus
has been used to define its own group the Carcharodontosauridae
which
includes other giant theropods such as Giganotosaurus,
Mapusaurus
and
Tyrannotitan.
All of these predators have proportionately large
skulls, large fenestra (skull openings), and serrated slicing
teeth designed for cutting flesh rather than crunching bone. The
Carcharodontosaurids seem to have evolved from earlier theropods like
Allosaurus,
and again this would display a different lineage from the
tyrannosaurs which evolved from a coelurosaurian lineage. The
carcharodontosaurids were quite common at one time during the
Cretaceous, being represented by Acrocanthosaurus
in North America,
Neovenator
in Western Europe and Shaochilong
in China. However the
carcharodontosaurids disappear from the fossil record before the end of
the Cretaceous, being replaced by tyrannosaurids
in the north and
abelisaurids
in the south.
Further
reading
- Wirbeltiere-Reste der Baharijestufe (unterestes Canoman). Ein
Skelett-Rest von Carcharodontosaurus nov. gen -
Abhandlungen der
Bayerischen Akademie der Wissenschaften,
Mathematisch-naturwissenschaftliche Abteilung, 9(Neue Folge): 1–23. -
E. Stromer - 1931.
- Predatory dinosaurs from the Sahara and the Late Cretaceous faunal
differentiation - P. C. Sereno, D. B. Dutheil, M. Iarochene, H. C. E.
Larsson, G. H. Lyon, P. M. Magwene, C. A. Sidor, D. J. Varricchio
& J. A. Wilson - 1996.
- A new method to calculate allometric length-mass relationships of
dinosaurs. - Journal of Vertebrate Paleontology, 21(1): 51–60. - F.
Seebacher - 2001.
- My theropod is bigger than yours...or not: estimating body size from
skull length in theropods - Journal of Vertebrate Paleontology 27 (1):
108–115 - F. Therrien & D. M. Henderson - 2007.
- A new species of Carcharodontosaurus (dinosauria:
theropoda) from the
Cenomanian of Niger and a revision of the genus. - Journal of
Vertebrate Paleontology, 27(4) - S. L. Brusatte & P. C. Sereno
- 2007.
- Balance and Strength—Estimating the Maximum Prey-Lifting Potential of
the Large Predatory Dinosaur Carcharodontosaurus saharicus. - The
Anatomical Record. 298 (8): 1367–1375. - D. M. Henderson & R.
Nicholls - 2015.