Name:
Helveticosaurus
Phonetic: Hel-vet-e-co-sore-us.
Named By: Peyer - 1955.
Classification: Chordata, Reptilia, Sauropsida,
Diapsida, Archosauromorpha?
Species: H. zollingeri (type).
Diet: Probably shellfish.
Size: Uncertain.
Known locations: Europe, Switzerland.
Time period: Anisian of the Triassic.
Fossil representation: Almost complete remains.
For
a long time Helveticosaurus was thought to be one
of the placodonts,
specialist marine reptiles that lived in the Triassic seas that fed
upon shellfish. However further analysis has revealed that only the
vertebra of Helveticosaurus are similar to the
placodonts, which has
led to Helveticosaurus being re-classed as a
diapsid (two holes in
the back of the skull, similar to lizards) and possibly an
archosaur, reptiles that were the dominant land animals of the
Triassic before the advent of the large dinosaurs.
Helveticosaurus
however was adapted for an aquatic life, although with a body similar
to the early unarmoured placodonts such as Paraplacodus
and Placodus,
it may not have spent all of its time in the water. Also like with
these placodonts, Helveticosaurus is thought to
have primarily swum
with a laterally undulating (side to side) movement of the tail
while using its legs to steer and change direction by pushing in the
opposite direction that it wanted to turn. Perhaps the best examples
of this style of swimming observable today are newts and marine iguanas.
The
skull of Helveticosaurus was quite robust with
short jaws, something
that has caused confusion amongst some people as to why they would not
be along the same proportions as other marine reptiles such as
nothosaurs and pliosaurs, especially so when you consider that
Helveticosaurus had caniform teeth. Usually
however such an
adaptation is seen in predators that need to focus bite force so that
they can bite through hard and tough prey. This is a simple principal
where the closer to the fulcrum (in an animal the point of jaw
articulation) an object is, the greater the crushing force it is
exposed to. This would see Helveticosaurus being
capable of crushing
the protective armour of shellfish like bivalves and crustaceans that
would have thwarted predators with less powerful jaws. These kinds of
prey would have also been the most suitable for Helveticosaurus
as its
swimming style meant that it was probably incapable of chasing after
faster prey like fish.
Further reading
- Die Triasfauna der Tessiner Kalkalpen. XVIII. Helveticosaurus
zollingeri, n.g. n.sp. - Schweizerische Pal�ontologische Abhandlungen.
72: 3–50. - Bernhard Peyer - 1955.