Puijila
Name: Puijila
(Young seal).
Phonetic: Pwee-ge-la.
Named By: N. Rybczynski, M.R. Dawson
& R.H. Tedford - 2009.
Classification: Chordata, Mammalia, Carnivora,
Pinnipedia.
Species: P. darwini (type).
Diet: Carnivore.
Size: Around 1 meter long.
Known locations: Canada, Nunavut, Devon Island
- Haughton Formation.
Time period: Aquitanian of the Miocene.
Fossil representation: One specimen of an almost
complete individual.
Morphologically Puijila looks a lot like an otter, however while otters are classed as musteloid mammals, the skull and teeth of Puijila clearly indicate that it was a pinneped, more commonly called a seal. As an early pinneped Puijila has helped to plug a gap in evolutionary theory concerning the appearance of seals since before this time only very primitive seal forms like Enaliarctos were known, but in this genus the aquatic life adaptations are already well developed. With a more otter-like body form, Puijila shows the transition between more terrestrial (land living) ancestors and the later pinneped descendants that are better adapted to swimming. This is analogous to two other mammalian genera, Pakicetus and Ambulocetus, that together help show the transition between land living ancestors and fully aquatic whales.
There
is one very interesting thing to note about both Puijila
and
Enaliarctos. At the time of its description Puijila
has heralded in
the news as the first of all known pinnipeds, however this may not be
exactly true. The type specimen of Puijila was
recovered from an
early Miocene deposit, while some remains of the more advanced
Enaliarctos are known from the late Oligocene, an
earlier period than
the Miocene. What this means is that the type specimen of Puijila
probably came from a late surviving population of more primitive
pinnipeds that were living at a time that other forms were already
developing better adaptations for a semi aquatic life. As such it’s
quite plausible that Puijila and other forms like
it actually had their
origins within the Oligocene, and if fossils of Puijila
(or very
similar basal pinnepeds) can also be found for this time, then this
would confirm without doubt the placement of Puijila
as an early form
pinneped.
Additionally
this would take some support away from the notion that pinniped
evolution was driven by glaciation in the North since Enaliarctos
already has early swimming adaptations while living much further south
on the Pacific coast of the United States. Instead it’s probably more
likely that seals adapted to take better advantage of more abundant
marine prey rather than try and compete with land predators that were
becoming ever more powerful.
An
otter like body means that Puijila had a very long
but slim body with
short legs. Aside from being streamilned while in the water this body
would allow Puijila to easily navigate around
submerged obstacles and
possibly head into burrows after prey. The bones of the feet also
have wide spacing which suggests that they were webbed to provide
additional push while Puijila was swimming.
Puijila
was named after the Inuktitut word for ‘young seal’ which is a
reference from this mammal’s placement in the evolutionary line of
pinnipeds. The species name also has an evolutionary connection since
P. darweni is named after Charles Darwin, the
English naturalist
who is today remembered for writing On the Origin of Species, a
scientific work that became the foundation for evolutionary science as
we know it today. Because of this work many animals have been named
after Charles Darwin, particularly what are seen to be transitional
forms. One example is the naming of the pterosaur
Darwinopterus
which
is seen as a connection between primitive and advanced pterosaurs.
Further reading
- A semi-aquatic Arctic mammalian carnivore from the Miocene epoch and
origin of Pinnipedia. Nature 458:1021-1024. - N. Rybczynski, M. R.
Dawson & R. H. Tedford - 2009.
----------------------------------------------------------------------------
Random favourites
 |
 |
 |
 |