Paraplacodus
Name:
Paraplacodus
(Almost Placodus).
Phonetic: Pah-rah-plak-o-dus.
Named By: Bernhard Peyer - 1931.
Classification: Chordata, Reptilia,
Sauropterygia, Placodontia.
Species: P. brioli (type).
Diet: Shellfish.
Size: 1.5 meters long.
Known locations: Italy (North).
Time period: Ansian to Ladinian of the Triassic.
Fossil representation: Partially preserved specimen.
Paraplacodus
was very similar to another placodont
named Placodus,
hence the name
which means ‘almost Placodus’, and as such it
would have looked
like a cross between a newt and a marine iguana with small teeth that
protruded from the front of the mouth. These teeth would allow for a
feeding behaviour where they were used to pick up shellfish from the
sea floor so that the robust flatter teeth towards the back of the
mouth could crush the shell and allow Paraplacodus
to eat the soft
flesh within.
Overall
Paraplacodus was morphologically similar to Placodus,
and even shared
the same rib development which saw the ribs curving backwards to give
better protection to the lower internal organs. However it still had
some notable key differences the most visible being the skull. The
skull of Paraplacodus was more proportionately
shorter and more gracile
than that of the larger Placodus, and also had a
more gently curving
snout. The front teeth of Paraplacodus were
positioned to point
further forwards from the mouth, while the rear teeth were smaller
but numerous. The orbital fenestra was also proportionately larger
than that of Placodus.
The
skull differences between Paraplacodus and Placodus
suggest that
while these two placodonts were similar, they may have gone for
different types of shellfish. The gracile skull of Paraplacodus
hints
that it had a weaker bite than the more robust Placodus,
and so it
may have preferred prey that had thinner shells. This also explains
the slightly different dentition of Paraplacodus
which would enable
it to get a finer grip on the thinner shell of a prey animal without
breaking it before getting it to the rear teeth.
Paraplacodus
also has an association with another placodont called Saurosphargis.
Further reading
- Paraplacodus and the phylogeny of the Placodontia
(Reptilia:
Sauropterygia). - Zoological Journal of the Linnean Society vol 130,
Issue 4 - Olivier Rieppel - 2000.
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