Xilousuchus
Name:
Xilousuchus
(Xilou crocodile).
Phonetic: Zih-loo-soo-kus.
Named By: Xiao-Chun Wu - 1981.
Classification: Chordata, Reptilia,
Archosauria, Crurotarsi, Rauisuchia, Paracrocodylomorpha,
Poposauroidea, Ctenosauriscidae.
Species: X. sapingensis (type).
Diet: Carnivore.
Size: Nased upon proportion comparisons to similar
rauisuchians, up to about 1.7 meters long.
Known locations: China, Shanxi Province -
Heshanggou Formation.
Time period: Olenekian of the Triassic.
Fossil representation: Skull and partial skeleton.
Xilousuchus
is one of the oldest known archosaurs and like many other primitive
forms it has a sail upon its back. This has seen Xilousuchus
placed
within the Ctenosauriscidae group of sail backed rauisuchian
archosaurs
that are typified by the genus Ctenosauriscus,
although Xilousuchus
is actually thought to be more closely related to another member of
this group called Arizonasaurus
that lived in what is now North America.
The
sail backed archosaurs should not be confused with the sail backed
pelycosaurs
like Dimetrodon
and Edaphosaurus
of the earlier Permian
period, although like them the exact function of the sails is open to
debate. Temperature regulation is one commonly proposed theory as
well as display, however the sails of rauisuchians like Xilousuchus
are more robust than in earlier sail backed animals. It may be that
they served an additional purpose of fat storage where reserves of fat
were built up in times of plenty so that the animal could survive
leaner times. It’s particularly important to bear in mind that
Xilousuchus and many others like it appear not that
long after the
single largest extinction event in the recorded history of the planet,
and that later forms of rauisuchian
archosaurs would live without the
sails. This might lend more support to the fat hump theory as such a
feature would help with the continued survival of one group of animals
into leaner times.
Further reading
- The discovery of a new thecodont from north-east Shensi. - Vertebrata
PalAsiatica 19:122-132 - X. Wu - 1981.
- A sail-backed suchian from the Heshanggou Formation (Early Triassic:
Olenekian) of China. - Earth and Environmental Science Transactions of
the Royal Society of Edinburgh 110 (3): 271–284. - Sterling J. Nesbitt,
Jun Liu & Chun Li - 2010.
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