Stories tagged Permian-Triassic

Dec
15
2010

If it had hands: it would be holding your life in them. Just saying.
If it had hands: it would be holding your life in them. Just saying.Courtesy splorp
Gather ‘round, Buzzketeers, so that I might tell you all a story.

“What story,” you ask?

Is it the one about the little blond girl who is killed by bears for breaking and entering? No, not that story.

Is it the one about the boy who killed an acromegalic man by cutting down the tree that held his fort? No, it’s not that story either.

Could it be the story about the little Blood member who couldn’t tell the difference between a wolf and her own grandmother, and was subsequently devoured by that very wolf? Oh, I wish it were, but it’s not that story.

No, the story I have for you all is even more enduring and horrifying than all of those. It is the story of biodiversity, and how it will freaking destroy you if you mess with it.

Sure, snort dismissively if you must, but you’ll soon be singing a different tune. A sad tune about how everything you ever knew and loved has been taken away from you.

“But how can a concept—and a boring concept like “biodiversity”—hurt me?” Ah, see, but what you don’t know can hurt you. You’re like the little blond girl, screwing around in a house that belongs to bears. She might not have known that it was a bear house (although it’s hard to imagine that she could have missed all the signs), and yet she was destroyed. So listen up.

You see, all biodiversity is is the degree of variation of living things in an ecosystem. Lots of biodiversity in an ecosystem, lots of different things living there. Little biodiversity in an ecosystem, few species living there. And biodiversity includes all forms of life, from your vampire bats and hagfish, to your streptococcus and your slime molds.

At the moment, biodiversity on the planet is on its way down. Lots of the things we do these days make life harder for other species, until there are very few or none of them left. And, sure, no one wants to see a panda get hit by a train, or watch an eagle being run over by road grading equipment, but who cares about the smaller, grosser stuff, like algae or germy things? We could probably do with a few less of those, right? Right?

Wrong, Goldilocks! An attitude like that is bound to get you turned into bear meat.

And here’s where my story begins (again)…

Once upon a time, long, long ago, everything died.

Well, not everything-everything, but pretty well near everything. It was called “the Permian extinction” (we’ve talked about it on Buzz before: here), and more than 90% of all marine (water) species and 70% of all terrestrial (land) species on the planet went extinct. It was way worse than the extinction that would eventually kill off the dinosaurs, and it took the planet a lot longer to recover from the Permian extinction.

What caused the Permian extinction? Oh, you know, a lot of stuff. Probably a lot of stuff. See, while we can more or less say that the dinosaurs were killed off by a giant space rock, it’s harder to say what did in the creatures of the Permian period. After all, the Permian ended almost two hundred million years before the extinction of the dinosaurs. But people have plenty of good guesses: maybe a few smaller space rocks hit the planet, maybe massive volcanic eruptions in what would become Asia kicked dust and poisonous gas into the atmosphere, maybe the oceans suddenly released massive amounts of methane… probably it was a combination of these things and more, and the extinction probably happened in waves before the planet became a good place to live again.

But here’s another straw for that dead camel’s back: the algae died. Not all of it, but lots and lots of the algae died. But why, and why did it matter? After all, it’s just algae.

Scientists aren’t sure exactly what cause so much alga—microscopic plant-like ocean life that turns sunlight into food—to die, but it looks like a sudden rise in the levels of sulfur in the oceans might have had something to do with it. It could be that there was an explosion in the population of sulfur using, hydrogen-sulfide releasing bacteria in the oceans, which would poison the algae.

In any case, there was a large die off of the sort of species we don’t give a lot of thought to. And what happened? The bear meat hit the fan!

Because they turn so much sunlight into so much food, algae act as the basis for most marine food chains. When the algae were gone, photosynthetic bacteria took its place to some extent, but the bacteria were a poor substitute, and the oceans were left with much, much less food. Also, algae produce a significant amount of the planet’s oxygen, and their absence would have created atmospheric changes as well.

This alone might have been enough to cause extinctions, and combined with the other natural calamities of the end of the Permian, it’s no wonder there was such a massive extinction event.

What a good story, eh? Now, if someone asks you what’s so great about biodiversity among the slimier and more boring species, you can just repeat this post, word for word. Or you can repeat this, the short version, word for word: “Because, Mom, if the algae die, we’ll be left choking and crying among the ruins of humanity for the rest of our short lives. And happy birthday.”

Aug
11
2007

A Permian anteosaurus: He feels vaguely nervous, and oddly sweaty.  (image courtesy of Wikipedia Commons)
A Permian anteosaurus: He feels vaguely nervous, and oddly sweaty. (image courtesy of Wikipedia Commons)
65 million years ago something very sad happened. Well, it was sad for the dinosaurs, because they all died, but great for us mammals. Here – I’ve written a little play about it:

Scene 1
Dinosaur 1: Hey, have you noticed that there seem to be a lot less of us these days?
Dinosaur 2: What? I don’t know. Why?
Dinosaur 1: Probably just my imagination. Forget about it.
Dinosaur 2: …
Dinosaur 1: Hey, what’s that thing up there?
Dinosaur 2: We call it the sun.
Dinosaur 1: No, that thing – it’s getting bigger, I think.
Dinosaur 2: Oh, not to change the subject, but did you watch Entourage last nigh*

Scene 2
(fiery, dusty chaos)

Scene 3
Rodent-like mammal: Yes!

The End

Anyway, the extinction at the end of the Mesozoic (dinosaur times) was a big deal. But, dramatic as it likely was, it was nothing compared to the extinction at the beginning of the Mesozoic.

Before the dinosaurs existed, the world was ruled by a different kind of animal, the therapsids, or “mammal-like reptiles.” These ranged from little rat like guys to huge fanged and clawed lion-like creatures. About 250 million years ago, though, at the end of the Permian period, there was an extinction event way bigger than the one that would eventually kill all the dinosaurs.

The Permian extinction killed off 90% of all the life on the planet, both on land and in the oceans. Life as we know it just squeaked by complete annihilation. The thing is, scientists still aren’t sure exactly what initiated the extinction. Whatever it was, it caused massive amounts of carbon dioxide, and other greenhouse gases to be released into the atmosphere. The earth would have gotten warmer and warmer, the oceans would have become acidic, and by the time things got back to normal, almost every species on the planet had died out.

Jonathan Payne, a paleobiologist at Stanford, is investigating one of the possible causes of the extinction – a massive volcanic eruption occurring at the end of the Permian. This eruption was the larger than any other that has happened in the last 600 million years, and it spread a four-mile thick sheet of basalt the size of the continental US over Asia. Along with the poisonous gases spewed by the volcano itself, it is believed that the spreading magma may have heated the coal-rich strata near the eruption and released vast amounts of carbon dioxide into the atmosphere. Then, you know, the whole horrible global warming and acidic oceans thing.

Fortunately, for all our CO2 production, we aren’t yet in the Permian extinction league of global warming gases. Still, Payne is comparing contemporary signs of global warming to those leading up to the Permian event. For example, under increasing environmental stresses, coral colonies tend to bleach (as algae leaves the reefs). Researchers will be examining fossilized coral colonies from the end of the Permian to see how they reacted to the changing environment. "We hope to reconcile the short-term processes we observe operating in the modern world with the very long time scales seen in the geologic record," says a researcher in Payne’s lab. If the analogy works, we could better understand the processes of past environmental change, as well as the potential future effects of the environmental changes that are occurring today.

My own theory regarding the Permian extinction largely focuses on the refusal of therapsis to carpool, and their insistence on driving larger vehicles than they really needed (cyconodonts were notorious SUV lovers). Unfortunately, this is extremely difficult to verify in the fossil record. I chalk this up to the poor preservation of pre-Triassic GM products, or, possibly, to the fact that therapsids had adapted to finding (and then losing) well concealed parking spots (they were, after all, much more primitive than us).

Jun
04
2006


Meteor Crater near Winslow, AZ: This crater formed when a meteor collided with Earth about 50,000 years ago. It is approximately 3/4 mile in diameter and 650 feet deep.
Courtesy Mark Ryan

A 300 mile wide crater (bigger than Ohio) has been detected beneath a half-mile of ice in Anartica. This crater is twice as big as the one thought to have killed the dinosaurs. Reseachers believe the impact may have broken up the Gondwana supercontinent, pushing what is now Australia northward.

Two separate data sets were combined to understand more about this impact. Radar to detect a crater, and gravity measurements to detect a mass concentration, or "mascon" in the same place. When a large mass slams into the earth, there is a rebound of mantle material up into the earth's crust creating a bump or mascon..

"On the moon, you can look at craters, and the mascons are still there," von Frese said. "But on Earth, it's unusual to find mascons, because the planet is geologically active. The interior eventually recovers and the mascon goes away." He cited the very large and much older Vredefort crater in South Africa that must have once had a mascon, but no evidence of it can be seen now.
"Based on what we know about the geologic history of the region, this Wilkes Land mascon formed recently by geologic standards -- probably about 250 million years ago," he said. "In another half a billion years, the Wilkes Land mascon will probably disappear, too." Ralph von Frese, a professor of geological sciences at Ohio State University

The Permian-Triassic extinction about 250 million years ago, when almost all animal life on Earth died out, may have resulted from this impact.

Not all scientists agree, however

Scientists contacted by [email protected] say they are sceptical, as no signs of such an enormous impact have been found in other, well-studied areas of Antarctica. Jane Francis, a geologist at the University of Leeds says, "That sequence has been worked on before, and no one has found evidence to support a massive impact like this," Paul Wignall, a palaeontologist at the University of Leeds, UK, who studies mass-extinction events says that few scientists will be convinced by the hypothesis until the team can precisely date their crater directly, and find rocks there that have been altered by the searing heat of the explosion.

Most think that the extinction started when a vast volcanic eruption released huge amounts of gas, including sulphur dioxide and carbon dioxide, into the atmosphere, causing acid rain and greenhouse warming. Von Frese notes that the explanations aren't mutually exclusive: the shockwaves from a huge impact could have travelled through the planet to trigger the eruptions in Siberia, delivering a devastating combination of disasters.

Too much ice covers the putative crater for a drilling expedition. But Von Frese hopes to make a research trip to Antarctica to look for rocks at the base of the ice sheet along the continent's coast that could attest to an impact.

Sources:
NatureNews
physorg
space
BBCnews
Yahoo news