Monjurosuchus
Name:
Monjurosuchus.
Phonetic: Mon-ju-ro-soo-kus.
Named By: R. Endo - 1940.
Synonyms: Rhynchosaurus orientalis.
Classification: Chordata, Reptilia,
Choristodera, Monjurosuchidae.
Species: M. splendens
(type).
Diet: Herbivore.
Size: Skull 5 centimetres long, total body
length about 40 centimetres.
Known locations: China - Yixian Formation.
Japan - Kuwajima Formation, Okurodani Formation.
Time period: Insectivore.
Fossil representation: Many individuals, some
almost complete with elements of soft tissue.
Today
the Yixian Formation of China is one of the most famous and most
studied fossil bearing formations in the world with many significant
prehistoric animals such as Eomaia,
Graciliraptor,
Confuciusornis,
Dilong,
Beipiaosaurus,
Yutyrannus,
Sinocalliopteryx
and
Psittacosaurus
all amongst many, many other animals all being found
there. However what many people do not know is that the very first
tetrapod to ever be named as coming from the Yixian Formation was a
small and unassuming little reptile named Monjurosuchus.
Since
being named in 1940, Monjurosuchus has been
variously described as
a rhynchocephalian and a pseudosuchian, though today Monjurosuchus
is
treated as a choristoderan, and within this group Monjurosuchus
is
the type genus of a sub group named as the Monjurosuchidae.
Monjurosuchus is noted as having large eyes as well
as numerous small
pointed teeth. The feet of Monjurosuchus are
known to have been
webbed but there are no other known aquatic adaptations. What stomach
contents that are known are fragmentary and seem to come from
arthropods.
Altogether
Monjurosuchus seems to have been a predator of
small invertebrates
that were either around a lake edge or within the shallows themselves.
The large eyes were likely enlarged to allow a greater amount of light
to be collected and processed. This might suggest that Monjurosuchus
came out at night, or alternatively allowed Monjurosuchus
to seem
better in the murky waters so that they could more effectively hunt.
The fact that the feet were webbed while the tail had no swimming
adaptation could indicate that Monjurosuchus were
more concerned about
manoeuvrability in the water as opposed to fast swimming. This would
be a definite plus when hunting through the shallows and having to push
through weeds and swim around submerged roots and branches. With the
eyes orientated to be in top of the skull, Monjurosuchus
probably
approached prey from below.
Further reading
- A new genus of Thecodontia from the Lycoptera Beds in Manchoukuo.
- Bulletin of the Central National Museum of Manchoukuo 2:1-14.
- R. Endo - 1940.
- Exceptional fossil material of a semi-aquatic reptile from China:
the resolution of an enigma. - Journal of Vertebrate Paleontology
20 (3): 417–421. - K. Gao, S. Evans, Q. Ji,
M. Norell, S. Ji - 2000.
- The choristoderan reptile Monjurosuchus from the Early Cretaceous of
Japan. - Acta Palaeontologica Polonica. 52 (2): 329–350. - R.
Matsumoto, S. E. Evans & M. Manabe - 2007.
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