Posted by: paulgarner | May 5, 2009

A walking pinniped

The Puijila skeleton. Courtesy http://nature.ca/puijila/index_e.cfm
The Puijila skeleton. http://nature.ca/puijila/index_e.cfm

Now this really intrigues me: Puijila darwini, the fossil mammal from the Canadian Arctic that’s being described as a transitional form between terrestrial carnivores and modern pinnipeds (seals, sea lions and walruses). I know it’s old news, having appeared in Nature back on 23 April, but I’ve only just had time to read the paper (Rybczynski et al 2009).

So what’s the lowdown? Well, Puijila darwini appears to be a pinniped, but unlike modern pinnipeds it has a long tail, and feet rather than flippers. There are indications that it was semi-aquatic, such as flattened phalanges that suggest the presence of webbing between the digits. Nevertheless, the fore- and hind-limbs are clearly much more like those of terrestrial carnivores than modern pinnipeds.

I’m fascinated by this. Firstly, because it’s another amazing fossil animal we didn’t know about before, and that’s always exciting. Secondly, because it reminds me about Kurt Wise’s proposal, in his paper at the recent Genesis Kinds Conference, that some semi-aquatic and aquatic mammals may not have been aquatic at the time of the global flood (Wise 2009 p.143). As Kurt has pointed out, several groups of aquatic mammals have fossil records that don’t extend all the way back to the Flood (the end of which is tentatively identified with the Cretaceous/Palaeogene boundary). Even taking into account the vagaries of preservation, this might lead one to conclude that these groups are, in fact, sub-baraminic and arose some time after the Flood. The pinnipeds, for example, make their first appearance in Lower Miocene sediments.

If I’m honest, I’m struggling to accept the radical idea that the whole of the Caniformia might constitute a single ark kind (c.f. Wise 2009 pp. 141, 153). But then I look at Puijila darwini and I wonder whether the pinnipeds really were descended from a more terrestrial ancestor, perhaps one that was on board the ark.

What I do know is that if Puijila really is a proto-seal, it won’t be the first time I’ve been surprised by God’s creation and I don’t suppose it will be the last.

P.S. It’s pronounced “pea-ooh-yee-la”. So it says here.

References

Rybczynski N., Dawson M. R. and Tedford R. H. 2009. A semi-aquatic Arctic mammalian carnivore from the Miocene epoch and origin of Pinnipedia. Nature 458:1021-1024.

Wise K. P. 2009. Mammal kinds: how many were on the ark? in: Wood T. C. and Garner P. A. (editors). Genesis Kinds: Creationism and the Origin of Species. CORE Issues in Creation No. 5, pp.129-161.

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Responses

  1. Hi Paul,

    I’ve been meaning to send you a note for quite some time congradulating you on your new blog. Thanks for the effort involved in doing this!

    Regarding Puijila: I haven’t looked into this at all, but I was wondering what convincing evidence is there for creationists to group Puijila with pinnipeds instead of Otters (Lutrinae)?

    Thanks again

    • Thanks for your kind words. I appreciate it and I’m pleased to hear that you’re enjoying the new blog.

      Although Puijila probably resembled an otter in overall appearance, its skeletal features seem to link it with the pinnipeds rather than the mustelids (the family to which otters belong). It shares, for instance, a number of cranial, dental and postcranial characters with Enaliarctos, a marine pinniped with flippers recovered from lower Miocene sediments. Also, the likely swimming mode of Puijila was different to that of otters. Puijila is thought to have used its four feet to paddle, whereas otters employ up-and-down undulations of the body with propulsive thrusts of the hind limbs. You’ll find more details in the paper by Rybczynski et al.


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