| Puijila | |
|---|---|
.jpg) | |
| Restored skeleton | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Carnivora |
| Suborder: | Caniformia |
| Family: | †Semantoridae |
| Genus: | †Puijila Rybczynskiet al.,2009 |
| Species: | †P. darwini |
| Binomial name | |
| †Puijila darwini Rybczynskiet al.,2009 | |
Puijila darwini is anextinctspecies of stem-pinniped (seal) which lived during theMiocene about 21 to 24 million years ago. About a metre (3 feet) long, the animal had only minimal physical adaptations for swimming. Unlike modern pinnipeds, it did not haveflippers and its shape wasotter-like, albeit more specialized; its skull and teeth are the features that most clearly indicate that it is a seal.[1]
It is considered to be the most primitive pinnipedimorph yet found. The genus name is anInuktitut word for a young seal; the species name honoursCharles Darwin.[2] Theholotype and only known specimen is a nearly complete fossil skeleton found in theHaughton Formation onDevon Island in the high Canadian Arctic. It is housed at theCanadian Museum of Nature,Ottawa,Ontario.
Puijila darwini was a semi-aquaticcarnivore which represents amorphological link in earlypinniped evolution. Its fossil shows enlarged, probably webbed[3] feet, robust forelimbs and an unspecialized tail. This suggests thatPuijila swam quadrupedally using its webbed fore and hind feet for propulsion. Phylogenetic studies including molecular evidence suggest a sister relationship between seals, bears and musteloids (weasels and otters). It had been popularly assumed that land mammals at some point transitioned to being more marine, in essence "returning to the sea" in order to gain some sort of survival advantage. However, fossil evidence of this transition had been weak or contentious. The discovery ofPuijila is important as it represents a morphological link in early seal evolution, and one that appears to morphologically precede the more familiarly structured genusEnaliarctos, despite apparently being a younger genus. In other words,Puijila is atransitional fossil that provides information about how the seals returned to the sea, similar to howArchaeopteryx illuminates the origin ofbirds.
This novel species wasdiscovered in 2007 byNatalia Rybczynski and her team using surface collection and screening at an early Miocene lake deposit of theHaughton Formation ofDevon Island,Nunavut,Canada.[4] The paleobotanical record suggests that the paleoenvironment around the lake comprised a forest community transitional between a boreal and a conifer–hardwood forest, in a cool temperate, coastal climate with moderate winters.Puijila darwini is the first mammalian carnivore found in the Haughton lake deposits. This is also an indication that the entire pinniped clade may have originated in theArctic.[1]
The initial find is credited to field assistant Elizabeth Ross, and was partly a matter of luck. Ross had been unexpectedly stranded with the team'sATV which had run out of fuel several kilometers from base camp. The brain case was discovered a year later on the first day of the 2008 field expedition by Martin Lipman, the team's photographer.[5]
