Oooook ... there's quite a bit of material on fish to tetrapod at Devonian Times - http://www.mdgekko.com/devonian/ as well as at http://www.origins.tv/darwin/tetrapods.htm - or anywhere that you can find anything about Jennifer Clack. Her book, Gaining Ground, has detail enough to reduce you to babbling.
Hi Oook! I second Coragyps’s recommendation of the Devonian Times. Look especially at the Who’s Who bit, where there’s pics of the actual fossils as well as drawings etc.
Also Jenny Clack’s book is great, but awfully detailed. (By a spot of serendipity, I’m reading it currently, in tandem with a Pratchett as light relief.) If you get any refs to it, or need any text or pics scanned from it, just let me know. And if you need anything more, I’m in occasional contact with Per Ahlberg, and can ask him. (He lurks regularly over at the IIDB; I’ll have to try and get him here.)
If you can get hold of a copy (try www.abebooks.com), Carl Zimmer’s At the Water’s Edge is also an excellent introduction to many of the weird names of these early tetrapod fossils.
If you're feeling brave, this site will tell you more than you probably want to know about these things too; have a browse around the branches of the cladogram at the top. Highly recommended!
For specific papers, try PubMed, which will give you the abstracts for sure and often the full papers. Try searching on Jenny Clack, Per Ahlberg, Mike Coates, E Daeschler, etc. I have several useful papers as pdfs (thanks to Per!) too.
In a nutshell, give me a shout if there’s anything you need on this.
Thanks very much for all of the links (from both you and Coragyps) and for the very kind offers of help. There is plenty of stuff for me to get stuck into so I will take some time to digest the basics. I will probably then post back so I can check that I have it right in my head.
So the understanding is that all taxa have the same process for obtaining and expelling energy and thus we are related and not just similar? Keep in mind I have no bias opinion right now, but I am trying to understand macro-e better then I do currently.
------------------ But Who Am I? NoBody
[This message has been edited by NoBody, 12-11-2003]
When lava from the region was recently dated, the result was about 70CE - showing an accurate result.
And when the layers of ice in the Greenland ice cap were counted, the layer of ash with the chemical signature of Vesuvius matched up, too. And there's another 100,000 layers older than that one in that same core...
quote:Dating methods are theoretical. Here is a question. Even if they are near to being correct, How do you know, I mean, How do you verify those dates? You can't, nobody has lived that long.
Dating methods are not theoretical. They are based on practical observations and measurements. Taking radio-dating, the half-lives of radiactive substances are measured in the lab ( I've done it myself in a Physics practical at Glasgow University many years ago - and with a gold-leaf electroscope!). It is a total fallacy that you need to observe them over a complete half-life. Given a sufficiently large sample and sufficiently accurate instrumentation, observation over a very small (compared to the half-life) time suffices.
How do we know the half-lives are constant over time. Two reasons. First, a negative reason, is the half lives had changed then the physical laws in the past would differ in a way that would be observable today.
Secondly, a positive reason, observations of radioactive decay in supernova show exactly the same decay rates as measured today.
Thirdly, again positive, all the methods (radiometric and non-radiometric) agree within the limits of accuracy of the methods.
Finally, and linked to the previous point, if the timing rates have changed all these different methods would have to change by exactly the same ratio in order to preserve the concordance of the results. This is physically impossible, at least for radio-dating. Any conceviable way in which decay rates would change would change the decay rates of different elements in a different way.
There is a very good exposition of the subject here