Friday, February 29, 2008

An Alternate Permian Period

One of the things that I talked about in my post on Gorgons I mentioned was that I wanted to do a post or so on an alternate ending to the Period Period. Zach and I have been talking about already. We have a basic working idea of what we want to do and our first critter is underway. Right now though, I thought I'd like to talk about some of the higher level decisions we've made.

The first and most obvious is that the Permian-Triassic Extinction didn't happen. Instead of the Siberian Traps going nuts in less than a million years, its eruptions are more gradual and take place over the course of ten million years. Now obviously, this will have its own geological label and a unique climate: sorta a continental variant on the Eocene climatically. Furthermore, it's going to have a higher sustained rate of turnover in species and genera than the periods before and afterwards. It will be a period of evolutionary innovation and a lot of nifty things are going to come out of it. We're going to have some fun showing off here. ;)

The Paleozoic doesn't end until what would have been the Triassic's end: the Permian gets an extension from 251 million years ago to 200 million years ago. This makes the Permian pretty darn long: 100 million years to be exact. Truthfully, if we were looking back (or sideways, as it may be in this case), the alternate Permian would probably be broken up into two ages since there was a largish turnover during the period from 251 - 241 million years (ATL). Any thoughts from the pros in the audience?

The extended Permian does end with a mass extinction. It kills much the same percentage wise as did the TJ Extinction (OTL). That is to say 50% of the species will get mopped. However, there's no big turnover or domination from one side of the mass extinction to the other two/three major classes of land vertebrates. The cause of the extinction is still largely the same: the blood basalt eruptions of the Central Magnetic Province (and the opening of the Atlantic).

A couple more things here. The therapsids and their derivatives are the dominate critters up until the KT Event: there are some parallel evolution bits happening here, but this TL is not one where the Age of Mammals comes early. Then anything goes. The oxygen dip that took place and dropped it down oh-so-low OTL is now drawn out and doesn't quite get as low either. The low point ATL is at around 140 million years ago and "only" reached the bottoming out of 19%. Much milder than OTL.

There's more, but that will have to do for now. I've gotta run.


Anonymous said...

call it "Siberian"... from 251-200 MA yrs ago and yes id love to see trilobites, sea scorpions and therapsids making it to modern times

Will Baird said...

Its called the XenoPermian:

Perhaps we ought to call the lower Xenopermian the Siberian and the upper Xenopermian the Arizonian? :)