Monday, October 19, 2009

Great Big Cat

I called this post “Great Big Cat” to match an earlier post called “Great Big Rat.” One was supposed to follow the other, to humorous effect. But then I got sidetracked by other things, and now Great Big Rat is way behind this post and it doesn’t really make much sense any more. However, since it is a post about a great big cat, I thought “why not leave the title as it is?” So I did.

Anyway, the last edition of Journal of Vertebrate Paleontology (Vol 29 #3, if you’re interested) attracted a lot of media attention because of a paper by Paul Scofield and Ken Ashwell that showed that the giant New Zealand raptor Hapagornis moorei, which was around recently enough for the Maori to have encountered it, was capable of flying off with a small child. They like that sort of thing, reporters: “giant eagle was maneater, say scientists” etc. It’s the sort of science everyone can enjoy. [Note to cryptozoologists: Hapagornis moorei is EXTINCT. And it lived in NEW ZEALAND. You cannot use it to explain Native American tales of “thunderbirds,” or apocryphal stories of small children in Texas being abducted by giant birds. The only Big Bird in America is the yellow one on Sesame Street. OK? (Sigh)]

Anyway, while you were poring over the giant eagle, you may have missed an equally interesting paper by Per Christiansen and John Harris, which was lurking away like a red-headed stepchild on page 934, just before those little mini-papers where guys discuss an interesting pig tooth they found or ‘fess up to giving some dinosaur a scientific name in an earlier paper that they have now found already belongs to a deep sea worm. Oops. This is a pity, because the Christiansen and Harris paper is really worthy of attention. It’s called “Craniomandibular morphology and phylogenetic affinities of Panthera atrox: implications for the evolution and paleobiology of the lion lineage.” But don’t let that put you off, because this paper is a cracking good read.

Let’s take a little trip back to Pleistocene North America, close to what’s now Los Angeles. 20,000 years ago, this whole area was a mix of sagebrush scrub and oak woodland inhabited by a whole bestiary of large mammals, including giant ground sloths, mastodons, mammoths, camels, horses, and bison. We know quite a lot about these animals, because they used to get stuck in pools of naturally occurring asphalt that were scattered across the region. Once they were stuck, big predators would come in to feed on them and get stuck in turn. The whole mess of bones and bodies then sank into the gunk at the bottom of the pools, where they lay undisturbed until scientific excavations began in 1906 (you can read more about this fascinating fossil site here).

Of the predators, one of the most abundant, and probably the best known, was the sabertooth cat Smilodon fatalis. Most people think of this animal as a bit of a prehistoric badass, and indeed it was an impressive animal, with canine teeth over 10 inches in length. But there was another big cat in the North American ice age, much less common in the tar pits (only 80 specimens are known as opposed to more than 2000 Smilodon specimens) but just as big, if not bigger, than the sabertooth. This was Panthera atrox.

Ever since it was first described by Joseph Leidy, in 1853, P. atrox has been a bit of a taxonomic puzzle. For a long time the consensus was that it was a very big lion; it was even classified as a subspecies of lion, Panthera leo atrox. Today lions are confined to Sub-Saharan Africa and a very small region of India, but they were common in Greece and Israel in classical times and even as recently as the 1940s could be found in Iran. During the Pleistocene they were probably the most widespread large mammal after humans, being found across most of Africa and Asia, together with Western Europe and both North and South America. Or at least, we thought there were lions in North and South America. But now it seems like “we” may have been wrong.

Now, you may have been laboring under the belief that it’s pretty easy to tell the difference between (for example) a lion, a jaguar, and a tiger. But that would be because when you go and look at them in a zoo, one’s spotty, one’s striped, and the other is…. neither spotty nor striped. Reduce them down to a bunch of bones, however, and life becomes a lot more difficult. There are morphological characters but it’s very hard to pick out the variation that separates the different big cat species from the variation that occurs within each species.

Undeterred, Christiansen and Harris attacked this problem from a multitude of angles – morphology of the skull, morphology of the mandible, dentition, allometry (studying the relationship between size and shape), multivariate analyses of 25 cranial variables, and something called a warp analysis of mandibular shape, which sounds like it comes from Star Trek. And the results are….?

Well, P. atrox is not a lion. Its craniomandibular and dental characteristics are more like those of a tiger or jaguar and it’s much larger than any other lion, fossil or extant. It seems to be most similar to the jaguar, and may have evolved from a jaguar-like cat that entered North America around 1 million years ago and subsequently gave rise both to modern jaguars and P. atrox. The South American P. atrox are probably not P. atrox at all, but just more jaguars. So instead of a big North American lion, we now have a giant North American panther with a skull up to 16 inches in length. Cool!

However, before we close the door on American lions, P. atrox is only found South of the American continental ice sheet. North of the ice sheet, in what is now Alaska, there were other Pleistocene big cats and these probably are lions. Unless some of them are tigers. Ugh. That’s enough of big cats.

[Oh dear, I thought I had got to the end of this piece, when I remembered that there was one thing I still had to deal with. CALLING ALL CRYPTOZOOLOGISTS! Panthera atrox is an EXTINCT species of big cat. Its purported survival into modern times, for which there is utterly NO EVIDENCE, does not explain “mysterious big cat sightings” in America. My suggestion is that you leave paleontology alone and start by looking for the guy down the road who’s running an unlicensed “animal sanctuary” and consequently does not report escapes]

1 comment:

  1. TO: the author

    FROM: someone interested in answers to cryptozoological mysteries rather than half assed assumptions.

    Why don't you go down the road and ask the guy who's running an unlicensed "animal sancutuary" and consequently does not report escapes, if he's missing any big cats; since you know everything? Believe me, I would, seeing as how I'm one of the many witnesses who's seen a black panther, but as there is no one down my road who owns such a sanctuary, I was under the impression that might know someone, seeing as how you just suggested it. And, let me know how that turns out.