Stories tagged therapsids

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).