Styletoctopus
Name:
Styletoctopus
(Stylet octopus).
Phonetic: Sty-let-ok-toe-pus.
Named By: Dirk Fuchs, Giacomo Bracchi, Robert
Weis - 2009.
Classification: Mollusca, Cephalopoda,
Octopoda, Octopodidae.
Species: S. annae (type).
Diet: Carnivore.
Size: Unavailable.
Known locations: Lebanon.
Time period: Cenomanian of the Cretaceous.
Fossil representation: Specimen preserved flat on a
rock slab.
In
2009 Styletoctopus was one of two genera of
extinct prehistoric
octopuses presented to the world, the other being Keuppia.
The fact
that octopus fossils were found at all is worthy of headline news since
with the exception of a hard keratinous beak, octopuses that we know
today are entirely made up of soft muscle tissue, something that very
rarely fossilises, and then usually only as an impression upon the
rock. Styletoctopus was preserved flat upon a
rock, and displays
the outlines of eight arms, something that confirms its identity as
an octopus and not another kind of cephalopod such as a squid (which
for clarity typically have ten arms). Styletoctopus
however does
also appear to have been a very primitive octopus since it has also
been found with the remains of a gladius.
A
gladius is in essence an internal shell, and a remnant of the outer
shells that the ancestral forms of Styletoctopus
would have possessed.
This means that Styletoctopus was not as advanced
as modern
octopuses, and while other cephalopods such as squid and cuttlefish
do retain internal shells, the closest match for the gladius of
Styletoctopus is actually the vampire squid,
Vampyroteuthis
infernalis. This does fit with fossil evidence since
ancient
relatives of the vampire squid, typically the genus Vampyronassa
have
been found in Jurassic age rocks, and together all of these genera
may represent a diversification and radiation of cephalopod forms that
eventually evolved into today’s modern forms.
Also
because the gladius in Styletoctopus is still quite
large when compared
to modern forms, it’s not impossible that Styletoctopus
may have
been more pelagic (living in open water) than many of today’s
octopuses. This is because of the internal shell, being bigger and
less flexible, would have been a hindrance if a Styletoctopus
ever
tried to squeeze into a rock crevice to hide from possible predators.
Finally the gladius of Styletoctopus is also the
inspiration for the
genus name since the internal shell is shaped like a stylet, a type
of flint point also known as a Minet ed Dhalia point which are found in
Lebanon, as was the Styletoctopus holotype fossil.
Another prehistoric octopus genus discovered from Lebanese fossil deposits is Palaeoctopus.
Further reading
- New octopods (Cephalopoda: Coleoidea) from the late Cretaceous
(upper Cenomanian) of Cakel and Cadjoula, Lebanon. - Dirk Fuchs,
Giacomo Bracchi, Robert Weis -1st Dec 2008 (pub January
2009)
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