Saturday, 7 November 2009

Sea Monsters

As I indicated last time, this will be a report of a session I attended about sea monsters. Not the Gloranthan sort, but ones in our world. Since Kingdom of Heroes is due for general release from 28th November, those waiting for a review of that may not have too much longer, and I don't at present have any other meetings of this sort planned before January, so that review should be the next thing up here.

The event, like some of the prior ones I've mentioned, was hosted by CFI London and held at Conway Hall. The first talk was presented by Charles Paxton of St Andrew's University. He defined a "sea monster", not unreasonably, as "an unknown marine animal larger than 2 metres" - that is to say, probably bigger than YOU.

By this definition, it's interesting to note just how many sea monsters have, in fact, been discovered in recent years. Now, granted, some of these are actually instances of animals that were already known, but not identified as being a separate species before. (An example of this kind of thing from dry land would be the recently discovered forest elephant). But some are genuinely new and surprising - the megamouth shark, for instance, was only discovered in 1976, and doesn't really resemble anything known before that time. Just within the last ten years, we've discovered at least two species of beaked whale, a group about which remarkable little is known, along with such things as giant rays. Given all this, it would frankly, be rather surprising if there weren't any new species out there that we haven't yet seen. In fact, it would be downright astonishing.

Most, of course, are going to be cetaceans (whales & dolphins) or cartilaginous fish (sharks & rays). Some will probably be other sorts of fish, seals, or even giant squid. They are not, on the whole, going to be plesiosaurs, but more on that later.

What the talk focused on primarily, however, was sightings. What should we make of reports of giant creatures roaming the seas that just don't fit any known species? Some may well be genuine, but many probably aren't. For one thing, even assuming that the reports are genuine (and most probably are, in fairness), if the observer isn't a zoologist, they might not know what they're looking at. Take this, for example, which shows a historical drawing of a sea serpent encounter and a modern photograph of what's very probably the same thing:

You can, perhaps, understand the mistake, but, of course, that photo isn't really a whale being attacked by a pair of sea serpents.

Come to that, the following critter looks pretty much like a sea serpent (it's about 30 feet long), but is perfectly well known to science:

It's called an oarfish, and it's really quite cool.

One might expect - and I certainly did - that most reports of sea monsters would be of the creature being some distance away. For one thing, that would make it harder to identify, if it was, in fact, something well known. Also, since it is very hard to measure distances at sea, one might well think that something is further away - and thus, much larger - than it actually is. But it turns out that's not so. In fact, according to Paxton's analysis of sightings from 1748 onwards, most sea monster sightings are at much closer quarters than one would expect by random chance. That is, if a given creature is real, you would reasonably expect people to have seen at least some of them from a fair distance off, but actually that's not what they report.

There's a number of possible reasons for this. It could be that, having seen the beast, people then often approach it to get a better look, and report that as the distance. It could be that, from a longer distance, people quite reasonably conclude it's probably something familiar they can't recognise that far away, and don't report it. For that matter, exaggerations, intentional or otherwise, are quite likely, especially when one is telling an exciting story.

The afternoon session was presented by Darren Naish, writer of the Tetrapod Zoology blog, of which I was already a fan. He focussed on the Prehistoric Survivor Paradigm; that is, the contention among many (but not all) cryptozoologists that many of the things they're hunting for are survivors of lineages so far known only to exist as fossils. Most obviously, of course, the plesiosaurs. After all, the argument goes, the coelacanth had been thought to go extinct at the same time as the dinosaurs, until it was found alive and well in 1938. So couldn't the same thing have happened to the plesiosaurs?

Well, no, actually it couldn't.

There are quite a few good reasons for this. For a start, the fossil record of the two groups is quite different. Coelacanths were already very much in decline by the time they disappeared from the fossil record with the dinosaurs, whereas plesiosaurs were extremely abundant - anything short of total extinction would surely have left a bunch of more recent species in the fossil record. Secondly, it's a damn sight easier to identify a plesiosaur fossil than a coelacanth one. The bones are much more distinctive in shape, they're unusually solid (making it easier for the creature to dive) so that they should fossilise better, and... well, they are a bit bigger. Harder to miss, you'd think. Coelacanth bones, by contrast, mostly look like those of other fish - at least, aside from the fins - and they're smaller and more fragile. And, on the gripping hand, since 1938, some fossil coelacanths have been discovered from post-dinosaurian deposits, so the gap is a good deal smaller than one might suppose.

Another good reason for thinking this unlikely is that most "plesiosaur" sightings don't look a whole lot like plesiosaurs. They look more like this model (picture from Wikipedia):

Which may be the classic view of what real plesiosaurs looked like, but is, in fact wrong. The most notable point here is the head - notice how it bends forward, like a swan. Real plesiosaurs had relatively stiff necks, so that the head should be tilted upwards if the neck were at this angle. In fact, plesiosaurs might not have been able to lift their necks this much anyway; the long neck was, most likely, for bending downwards to pick shellfish off the bottom. But, even if it could do so, the animal's centre of gravity would have meant that the poor creature would have gone over if it had tried to achieve such a feat.

There was particular discussion of the "merhorses" reported from the northern Pacific. They may, or may not, be an unknown creature, but whatever they are, they're certainly not a plesiosaurs, because the descriptions really don't come close. Some kind of unknown long-necked seal is a better bet, if it's not just misidentification of something otherwise known.

Similar objections apply to other claimed prehistoric survivors, of which the most prominent are perhaps mosasaurs and basilosaurids. Claims that they may have evolved into something quite different since they vanished from the fossil record really don't address the absence of that record, and are a bit like groping for an excuse. Plus, it's fairly unlikely, as is sometimes claimed, that modern plesiosaurs might be furry, or that some modern basilosaurids might look like a cross between a turtle and a centipede (no, really).

The afternoon concluded with a workshop playing with a computer program to estimate the likelihood of something still being around after a gap in the fossil record, and trying to estimate the species diversity of coloured straws in a bucket (courtesy of yours truly, since nobody else volunteered!)

Oh, and if you're still trying to puzzle out that first photo: there are two whales in that photo. Two very happy boy whales...

1 comment:

Darren Naish said...

Hi, thanks for the good writeup and glad you enjoyed the event. I'm trying to find out if anyone has photos of the event: I took a few pics of Charles on stage but they've come out very poorly. If you can help, please email me at eotyrannus at gmail dot com.