Name:
Aegisuchus
(Shield crocodile).
Phonetic: Ay-je-soo-kus.
Named By: Casey M. Holliday & Nicholas
M. Gardner - 2012.
Classification: Chordata, Reptilia,
Crocodylomorpha, Aegyptosuchidae.
Species: A. witmeri (type).
Diet: Carnivore/Piscivore.
Size: Skull estimated between 2.08 and 2.86
meters long. Total body size estimated between 15 and 22
meters long depending upon what kind of crocodile form it was (refer
to main text for detail).
Known locations: Morocco - Kem Kem Formation.
Time period: Cenomanian of the Cretaceous.
Fossil representation: Partial skull
It
is becoming increasingly clear that the dinosaurs were not the only
large reptiles that were around in the Mesozoic, and the discovery of
the partial skull of Aegisuchus is a further
example of this.
Although incomplete, the partial remains are from a huge skull,
but at the time of writing it is not known exactly what form this
skull took. Because of this, Aegisuchus has
been envisioned as both
a more standard crocodyloform, and a gharial-like crocodile with a
longer, slender snout.
This
also leads to a lot of speculation about just how big Aegisuchus
was.
If like a standard crocodile, it may have been between sixteen and
twenty-two metres long, if gharial-like, then fifteen to twenty-one
metres long. Unfortunately the only way we could be certain to the
size of Aegisuchus is if elements of the post
cranial skeleton were
found, the more complete the better. Unfortunately again the odds
are stacked against this happening as the more solid parts of
crocodiles such as the skull, teeth and scutes (bony armour) are
usually all that remain (though exceptions are known). If the
estimates of Aegisuchus are correct however, then
it will certainly
have been one of the largest crocodiles of all time, and a serious
contender for the largest crocodile ever. For more ideas upon how big
prehistoric
crocodiles could get, check out the table below.
Aegisuchus
was chosen as the name of the genus because of the presence of a bony
boss of bone that was on top of the skull. This is similar to designs
of the Aegis shield from Ancient Greece which was a circular shield
with a smaller boss (like half a sphere) in the centre. The boss
on these ancient shields was often stylised into the head of the Medusa
and were often seen carried by Ancient Greek gods such as Zeus,
Apollo and Athena, though often it would be a breastplate instead of
a shield.
The
actual skull of Aegisuchus is believed to have been
flat with eyes that
pointed up instead of forward. If correct then Aegisuchus
may have
lain just below the surface of the water, while the surface glare
masked its approach from any animals that may have been drinking on the
shore. This would allow Aegisuchus to close in
unseen until the
moment it struck. Alternatively, Aegisuchus may
have lain at the
bottom of water systems and ambushed creatures like fish or swimming
dinosaurs from below.
We
do not yet know for certain what kind of animals Aegisuchus
showed a
preference towards hunting, if any. Future discoveries of teeth,
maxilla’s and mandibles may help to determine this but these of
course need to be made. Dinosaurs were certainly a viable option as
many different kinds are known from the Kem Kem Beds of Morocco. If
however Aegisuchus were a fish hunting species,
then the large size
might denote a preference for preying upon larger fish genera such as
the giant sawfish Onchopristis
which is also known from the Cenomanian
of Morocco.
Name | Time/Location | Size (meters) |
Deinosuchus (alligator-like crocodile). | Cretaceous/USA. | 10-12 |
Gryposuchus (gharial-like crocodile). | Miocene/S. America. | 10 |
Mourasuchus (alligator-like crocodile). | Miocene/Peru. | 12 |
Purussaurus (caiman-like crocodile). | Miocene/S. America. | 11-13 |
Rhamphosuchus (gharial-like crocodile). | Miocene/India. | 8-11 |
Sarcosuchus (crocodile). | Cretaceous/Africa. | 11-12 |
Smilosuchus (phytosaur *not a croc). | Triassic/USA. | 12 |
Stomatosuchus (crocodile). | Cretaceous/Egypt. | 10 |
3 of todays largest living crocs below | ||
Alligator mississippiensis (American alligator). | Present/S. E. USA. | 3.4 average - up to almost 6. |
Crocodylus niloticus (Nile crocodile). | Present/Africa. | Average up to 5, largest up to 6.45. |
Crocodylus porosus (Salt water crocodile). | Present/India, S. E. Asia, N. Australia. | Average 4-5.5, largest recorded 6-6.6, possibly slightly bigger. |
Further reading
- A New Eusuchian Crocodyliform with Novel Cranial Integument and Its
Significance for the Origin and Evolution of Crocodylia, Casey M.
Holliday & Nicholas M. Gardner - 2012.