Tuesday, August 31, 2010

The Day After (the Dinosaur's) Tomorrow

I Tivo'ed Last Day Of The Dinosaurs. Feh.

The easy criticism is that it's animal Death Pr0n (not that there's anything wrong with that; I like North American Hunter). The story line is poorly written - poor dinosaurs! - but like I said, this is the easy criticism. The bigger criticism is that the story of the killer asteroid at the K-T boundary is mostly wrong, at least as told in shows like this. And therein lies the interesting part of the tale.

First, let's level-set: it's indisputable that an asteroid or very large meteor did hit the Earth 63 Million years ago. The evidence for this is pretty solid, not least the Iridium layer at the K-T boundary separating the Cretaceous ("K") and the Tertiary ("T") periods (K-T, see?).

Second, the Canonical narrative - a vigorous, thriving Dinosaur period snuffed out in the blink of an eye is almost certainly wrong. The Dinosaur world was in terrible trouble before the impact. The rate of speciation (actually, the creation of the next larger grouping, Genera) had been falling for millions of years. While the number of individuals represented in the fossil record remained roughly the same, they increasingly were made up from a smaller and smaller number of genera. For example, in the Hell's Creek formation, something like 80% of all individuals were from only a single genus (Tricerotops). That's not an healthy ecosystem, and Hell's Creek wasn't the only one - pretty much all the layers immediately below K-T show ecosystems in big trouble. And this wasn't anything new.

Dr. Robert Bakker in his indispensable (though a little dated) The Dinosaur Heresies, writes of this:
I first became aware of this pattern of evenness [a measure of how many different types of dinosaurs lived in a particular place at a particular time] in the evolution of the dinosaurs when I was a graduate student. It was clear that, even if a cosmic collision had killed off the very last dinosaurs, all the dynasties had been badly weakened from some other cause. I turned to checking the other great extinctions to determine whether there had been a disturbance of evenness before the final collapse on those occasions as well. I invested three years collecting evidence from the museums of Africa, Europe, and the United States. After counting and measuring thousands of skulls and skeletons, the killing agent's mode of operation came into sharp focus. Every well-recorded mass extinction fit the pattern of the late Cretaceous. Long before each final extinction, a decay in evenness had occurred. The saber-tooth gorgons of the Tartarian Epoch are a perfect case in point. Their ecosystem precisely displayed the typical three stages: a time of faunal richness, a subsequent decay of evenness, and the final collapse, when the gorgons disappeared entirely.
Where was the asteroid at the end of the Tartarian? Actually, you don't need one. As competition drives evolution in a stable environment, you would expect to see the emerging domination of a smaller number of genera. The longer the period of stability, the greater the domination. No mystery there.

Now add in a suddenly changing climate - new mountains draining the North American inland sea, for example, and you have a much less diverse gene pool from which to select new species. If it gets too thin, you get collapse. No need for a deus ex machina from Outer Space to cut down T. Rex.

So why the fascination with the Death Star? Partly, it's dramatic, and clueless TV producers will gravitate to dramatic. Like the TV shows showing crime scene reconstruction have little in common with the patient, nay almost boring grunt work that actually takes place. It's a Hallmark Moment, showing fire raining down from the skies and hundred meter tsunamis.

But that doesn't explain why the scientists have lined up behind the theory, and that's the interesting part. What's with them? I think that the answer is politics.

I've posted before about the Drake Equation, and the time that Carl Sagan spends talking about the possibility of nuclear extinction:
Now look, I don't have a problem with conjecture, as long as you call it that. But Sagan doesn't. He doesn't explicitly say that it's not science, and he doesn't explicitly say it is. He also does something very interesting: he doesn't remotely spend the same amount of time or emphasis on each variable. Sagan talks a lot about the variable for intelligent civilizations that blow themselves up. He even tries a couple of different values for that variable, to see how the number N changes. Go watch it again, paying attention to this emphasis. It's quite striking.

Things that we cannot control are glossed over, even if they would massively effect the overall outcome. Things that are politically top of mind are covered in depth. Does this remind you of anything?
Alvarez and his team discovered the Iridium layer marking the K-T boundary in 1980. Carl Sagan filmed Cosmos in 1980. Ronald Reagan was elected - promising to end détente - in 1980. Something was in the air.

Occam's Razor tells us that the simplest explanation is the best, when it comes to things scientific. We see something wildly not simple regarding the scientist's explanation of the dinosaurs' extinction. Occam's Razor tells us that the simplest explanation is best for why scientists act the way they do: they like getting phoned up by TV producers, and they like getting out a leftie message of you can't hug Brontosaurus* with Nuclear Arms.

But the show had way cool CGI animations of Pterodactyls getting shot down by flying asteroid detritus. Go, video production!**

* Yeah, I know: Brontosaurus was Jurassic, not Cretaceous. And everyone digs on Apatosaurus, not Brontosaurus. First, use of the name Apatosaurus is a plot by the KGB to undermine God Fearing American values. Second, even Blogger thinks it's Brontosaurus (which its spell checker recognizes, in great contrast to the lack of recognition given Apatosaurus). Third, Steven Jay Gould covered this in more than adequate depth. Go read.

** #1 Son wants to go into Internet video production.


Jon Woolf said...


But that doesn't explain why the scientists have lined up behind the theory, and that's the interesting part. What's with them? I think that the answer is politics.

Pretty much, yeah. At least, that's how I understand it. Luis Alvarez was a great scientist, but AIUI he left a lot to be desired as a human being. He had a forceful personality combined with an abiding contempt for 'soft sciences' like paleontology. He and his comrades found the iridium layer, determined its ET origin, and jumped to the conclusion of the Asteroid Doomsday scenario. When paleontologists (who knew the fossil record, as Alvarez did not) tried to argue, he essentially told them "We're scientists and you're not. We're telling you what happened. Now shut up and go back to playing with your little bones."

Alvarez had powerful allies and a formidable reputation. No one really wanted to argue. The few that did ... well, things happened to them. In some cases it was clearly coincidence. In others, it was their own troubles that did them in. But in some cases, it certainly seems that there was some kind of organized attempt to shut them up. Much like the situation with AGW today. In fact, to my eye the parallel is so close that it's one of the reasons I don't trust AGW theory.

Atom Smasher said...

Yeah, I have a rough time explaining the Deccan flats and otehr geological rough bottlenecks that were going on right here on earth without a smack from space. And you are 100% correct about the general march of the Dinos. They ran things for what, 150 million years? A pretty good run, but at the end they were pretty specialized.

Jack Sepkoski was a guest at one of the seminars I was in back when I was in grad school, and he calmly showed how patterns can emerge fro pure coincidence. Pretty neat stuff. The scientist he married though...? Ugh. Nasty piece of work she was.

Ritchie said...

There is supposed to be some evidence for multiple large meteor strikes about the time of the K-T event. Last I read, they were too close in time to tell any difference. And they're not in places very friendly to strangers.