Why No Plant Fossils?

[Bev]

Hi Guys and Gals of thefossilforum!

I am hunting in the Galena Formation, Ordovician Era, in SE Minnesota. It is a very, very fossilized area. But I never find any plant fossils!

I have seen fantastic plant fossils displayed on the Forum, so they do get fossilized.

Why not in the Galena here?

Thank you for your time and consideration.

Bev

[Fossildude19]

Bev,

What gets fossilized in a certain area has to do with the location of that area.

I believe you are finding no plants because your area was a marine environment, and what fossilized there were the marine or sea creatures that lived there.

You would expect to find plants in swampy or fresh water lake environments, where conditions were conducive to fossilization of plants that fell or were blown into the lakes or swamps.

Hope this helps to clear things up a bit.

Regards,

[Bev]

Thank you Tim! That does help me understand a bit. So, only land plants are fossilized and only in fresh water.

Bev

[ahuijsmans]

Hi Bev,

Well yes and no. I have fossilised sea weed so even that fossilises but perhaps the formation you are hunting is not from a 'near shore' environment? And even then, land plants in the ordovician are incredibly rare, only found in a handfull of places in the world. Look up Cooksonia.

There are near shore environments where cooksonia is found, presumably washed there by rivers or rains..

[Fossildude19]

Thank you Tim! That does help me understand a bit. So, only land plants are fossilized and only in fresh water.

Bev

Well Bev,...

There are some exceptions to this - so it is possible that you could find a plant fossil in marine sediments, but it is a greater possiblilty in

in fresh or brackish water environs, where plants were more closely associated with water filled areas.

For instance, I know that some carbonized wood/ plant matter has been found in one of the Devonian areas I hunt from time to time in Upstate New York. More commonly found are sea creatures - trilos, cephs, and brachs, and corals, but from time to time some plant matter is found.

SEE THIS LINK.

But this is a relatively rare occurrence.

Regards,

EDIT: And as ahuijsmans has pointed out, plants from the Ordovician are extremely rare - Plants were just starting to get a foothold on the land during that time period.

Edited February 4, 2013 by Fossildude19

[erose]

What, when and where stuff gets fossilized is a whole science of it's own: Taphonomy. As stated so well your Galena Formation is a marine environment AND millions of years before plants are anything more than a low dense ground cover. But even in a marine environment some fossils you might expect can be absent. A great example is the very similar Cincinnatian Series (Upper Ordovician). There is a great book: A Sea Without Fish: Life in the Ordovician Sea of the Cincinnati Region by David L. Meyer and Richard Arnold Davis with a chapter by Steven M. Holland. Indiana University Press, Bloomington, Indiana,2009, $44.95, hardcover, 346 pp. It is a great book for anyone collecting in the Ordovician or just plain interested in paleontology.

[Bev]

Thanks Erose!

[Rockwood]

What, when and where stuff gets fossilized is a whole science of it's own: Taphonomy. As stated so well your Galena Formation is a marine environment AND millions of years before plants are anything more than a low dense ground cover. But even in a marine environment some fossils you might expect can be absent. A great example is the very similar Cincinnatian Series (Upper Ordovician). There is a great book: A Sea Without Fish: Life in the Ordovician Sea of the Cincinnati Region by David L. Meyer and Richard Arnold Davis with a chapter by Steven M. Holland. Indiana University Press, Bloomington, Indiana,2009, $44.95, hardcover, 346 pp. It is a great book for anyone collecting in the Ordovician or just plain interested in paleontology.

I'm not familiar with the book. Does it refer to a preservational bias ? If I remember right acidic sediments are more likely to preserve plant material, and alkaline environments favor bone and shell.

[erose]

I'm not familiar with the book. Does it refer to a preservational bias ? If I remember right acidic sediments are more likely to preserve plant material, and alkaline environments favor bone and shell.

Actually the book title is based on the fact that no fish fossils have been found in those rocks. They occur in other Late Ordovician locations. And as far as I know plants are not present either, with the exception of marine algae.

[Rockwood]

Actually the book title is based on the fact that no fish fossils have been found in those rocks. They occur in other Late Ordovician locations. And as far as I know plants are not present either, with the exception of marine algae.

There's a chemicall bias that can exclude bones from formations with shell fossils to isn't there ?

[Scylla]

Annother source of bias is our own ability to recognise an algal fossil. Everyone knows a fern when they see it, how many of us can draw a good algae?

[Bev]

This is limestone, so we are alkaline. Lots of shell, coral, algae, trilos, crinoids. There is a current thread on recepticilious (sp?) and we have a lot of it and I show some I have found and given away.

Bev

[erose]

There are marine algae represented in the Cincinnatian. And the lack of teeth, armor or other fish bits is still unusual.

[Wrangellian]

Bev, if you find any obvious plants in your formation, let us know. Given the age it could be important.

I have land plants in my local marine, but I'm working in the Cretaceous so it's not unusual, even though my stuff is relatively deepwater sediment. Just to show it does occur.

[Bev]

Thanks for letting me know! I wouldn't have considered it important!

Bev

[JimB88]

the rarity of land plants from that period makes it important. Land plants dont really get going until the following period the Silurian. As far as algae goes I find fucoid or brown algae here in the Mississippian quite often (basically its a thin form of seaweed.)

[Fossildude19]

the rarity of land plants from that period makes it important. Land plants dont really get going until the following period the Silurian. As far as algae goes I find fucoid or brown algae here in the Mississippian quite often (basically its a thin form of seaweed.)

Nice ones, Jim!

Regards,

[Stocksdale]

I'd imagine that most ordovician terrestrial rocks would be devoid of fossils since the land was barren at the time. I also assume that fish would still be very rare and only in specific niches in the late ordovician. Is this right? That book "A sea without fish" sounds interesting. I think I'll check that out.

[Stocksdale]

Looks like Cooksonia doesn't even exist in the Ordovician.

"The earliest Cooksonia date from the middle of the Silurian (the Wenlock epoch)"

http://en.wikipedia.org/wiki/Cooksonia