raindropple

"The cyanobacteria have an extensive fossil record. The oldest known fossils, in fact, are cyanobacteria from Archaean rocks of western Australia, dated 3.5 billion years old. This may be somewhat surprising, since the oldest rocks are only a little older: 3.8 billion years old!

Cyanobacteria are among the easiest microfossils to recognize. Morphologies in the group have remained much the same for billions of years."

I am very interested as to why these fossils did not follow the normal evolutionary process, however I must admit that I do not know much about Darwin etc.

I have two requests:

1. Could someone please explain why these fossils remained mostly the same till today.

2. What forms were before this since nothing older was to date discovered? Put in another way. How did these bacteria form if nothing older was found?

Any input would be appreciated .

Godless Dave

Can you post a link to the original article?

raindropple

<a href="http://www.accessexcellence.org/bioforum/bf02/awramik/toc.html" target="_blank">http://www.accessexcellence.org/bioforum/bf02/awramik/toc.html</a>

I found this site. It partially explains why no earlier fossils were found.

This raises other questions and no1. still remains answered.

Another question would be:

Where are the pre or in between fossils(of higher life forms, like what came after the bacteria, and then after that,etc ), or did the impacts also destroy those?

[ May 15, 2002: Message edited by: raindropple ]</p>

Queen of Swords

Hello raindropple,

An excellent book that will answer your questions regarding microbial evolution is Microcosmos by Lynn Margulis and Dorion Sagan. It is written for the (intelligent) layperson, and is a fascinating read.

<strong>1. Could someone please explain why these fossils remained mostly the same till today.</strong>

If your question is "why have cyanobacteria remained the same", I would answer, why not? If they are very well adapted to their environment, and their environment does not greatly alter, why shouldn't they stay the same?

<strong>2. What forms were before this since nothing older was to date discovered? Put in another way. How did these bacteria form if nothing older was found?</strong>

What forms of life were before this? Probably chemicals that could replicate themselves - obviously we wouldn't find fossils of these. Again, Microcosmos spells it out a great deal better than I've done.

Hopefully your thread will be moved to the Evolution/Creation forum where extremely educated people can enlighten both of us further.

Pitshade

Off you go...

lpetrich

As to cyanobacteria looking very similar over 3.5 billion years, a simple answer was pointed out: their shape has been good enough for them for all that time.

Also, are the earliest ones really "cyanobacteria"? Did they really release oxygen? They could have been cyanobacterium-like, but dependent on some different source of hydrogen equivalents, such as oxidizing iron from soluble Fe++ to insoluble Fe+++.

That would explain both the Banded Iron Formations (lots of Fe+++) and the paucity of free oxygen in the Earth's atmosphere before about 2.3 billion years ago.

Dr.GH

Jo Que, amigos!

You ask a lot of qustions and instead of trying to answer them in a post (or 10 posts) I am going to point you ar some journal articles. A good number of these are avialable online, so try your search engine on the citations. The titles should make it fairly clear as to what part of your questions ar going to b addressed.

Brocks, Jochen J., Gram A. Logan, Roger Buick, Roger E. Summons
1999 Archaen Molecular Fossils and the Early Rise of Eukaryotes. Science 285 (5430):1033

Dalrymple, G. Brent,
1991 The Age of the Earth Stanford: Stanford University Press

Dyall, Sabrina D., Patricia J. Johnson
2000 “Origins of hydrogenosomes and mitochondria: evolution and organelle biogensis.”
Current Opinion in Microbiology 3:404-411

Hedges, S. Blair, Hsiong Chen, Sudhir Kumar, Daniel Y-C Wang, Amanda S. Thompson,
Hidemi Watanabe.
2001 “A genomic timescale for the origin of eukaryotes” Bio-med Central: Evolutionary
Biology 1:4
<a href="http://www.biomedcentral.com/1471-2148/1/4" target="_blank">http://www.biomedcentral.com/1471-2148/1/4</a>

Mojzsis, Stephen J., T. Mark Harrison,
2000 “Vestiges of a Beginning: Clues to the Emergent Biosphere Recorded in the Oldest
Known Sedimentary Rocks” GSA Today, April

MOJZSIS, STEPHEN J., T. MARK HARRISON, ROBERT T. PIDGEON
2001 ”Oxygen-isotope evidence from ancient zircons for liquid water at the Earth's
surface 4,300 Myr ago” Nature 409, 178-181 (11 January )

Rosing, T. Minik
1999 13C-Depleated Carbon Microparticles in &gt;3700-Ma Sea-Floor Sedimentary rocks
from West Greenland. Science 283 (5402): 674

Schopf, J. William
1994 “Disparate rates, differing fates: Tempo and modes of evolution changed from the
Precabrian to the Phanerozoic” PNAC-USA v.91: 6735-6742

Whitehouse, Martin.
2000 “Time Constraints on When Life Began: The oldest Record of Life on Earth?” The Geochemical News #103, April.

Xiong, Jin, William M. Fischer, Kazuhito Inoue, Masaaki Nakahara, Carl E. Bauer.
2000 “Molecular Evidence for the Early Evolution of Photosynthesis” Science 298(5485): 1724

These are just a small taste of the available literature. If you read the bibligraphies of these articles you will gain additional leads to follow. Also Science and many other journals can tell you which new articles have referenced these.