Michigan Fossil Coral?

[MICHIGAN_MAN]

I pulled this from a farm field in Sanilac county MI. As far as I can tell it's from the Mississippian Era around 340 million years old? Searching the net, I found this map and that's what I'm going by.

http://geology.about.com/library/bl/maps/n_statemap_MIold1200.htm

Searching the net for Michigan coral mostly brings up the Petoskey state stone. I don't think this is Petoskey. Anything you can tell me would be much appreciated.

Thanks Anthony

[Shamalama]

Nice coral reef section you have there. I can't be sure of the age ID as it could be a cobble left by a glacier but you sure have some nice exampled of Coral or Bryozoa fossils.

[MikeD]

Welcome to the forum. Looks like a great example a whatever kind of coral it is. I think the smaller "branches" look like bryozoan fragments. Looks like there might be a brachiopod in the lower left quadrant of that first picture. That may help to pin down the age. A close up of one of the detailed stalks could also help. Wish I could help more.

[MICHIGAN_MAN]

Hi, thanks for the replies. Yeah, it's big, weighs 50.5 lb and roughly 16"x11"x6" in size.

Here are some more PICS.

[Terry Dactyll]

Michigan_Man..... thats a very nice piece of the seabed.... well done saving that...

[Phoenixflood]

Michigan_Man..... thats a very nice piece of the seabed.... well done saving that...

It sure is I'm not really sure about the age though but it seems like you have narrowed it down a bit.

[MICHIGAN_MAN]

Thanks guys, after looking at some PICS, It does look like some type of bryozoan. It sat in a big rock pile behind my house for years, until the rain washed all the dirt off and I noticed it a few days ago. I wish I could know more about it, but after reading this I don't think I'll ever know for sure what kind.

"Bryozoans are common today in shallow-water marine environments and were common in the past; at least 3500 living and 15 000 fossil species are known. The fossil record of the phylum extends over 500 million years."

"bryozoans The bryozoans, sometimes also called the Ectoprocta, are a phylum of colonial, mostly marine, organisms. The individuals or zooids are physically connected and form a calcareous skeleton, the zooarium, that is commonly similar in appearance to the structures formed by other colonial organisms such as corals and hydrozoans."

Is it not a coral?

What I do know is it was found in an area of Michigan where the bed rock is around 340 million years old and Michigan was covered by a shallow sea at that time. This would fit in with what I have, but much of the state is covered with glacial drift, ground-up Canadian rocks bulldozed onto Michigan by several glaciers.

I also found this helpfull...

The Paleozoic: Paleozoic rocks are well represented in Michigan. This part of North America lay near the equator in the Early Paleozoic and fossils indicate that trilobites and brachiopods proliferated in the warm, tropical Cambrian waters that covered the continent. This shallow sea persisted through the Ordovician, Silurian, and Devonian Periods. During this long interval of time, a typical marine fauna dominated by brachiopods, trilobites, crinoids, and corals thrived. Fossils of these organisms are abundant in Michigan’s Paleozoic rocks.

The shallow seas that had covered Michigan for so much of its early history withdrew for the last time during the early part of the Carboniferous. In the Late Carboniferous, nearshore coal-forming swamps characterized Michigan. Fossils of ferns, scale trees (Lycophyta), and other plants dominate the fossil record of this time period.

The Paleozoic and Mesozoic: The Permian, Triassic, and Cretaceous Periods are not represented in Michigan. Any sediments (and the fossils they may have contained) that were deposited during these time intervals were subsequently removed by erosion. The Jurassic Period (between the Triassic and Cretaceous) is known only from drill cores of red sandstone that contain fossil plant spores of Jurassic age.

The Cenozoic: There are no sediments or fossils from the Tertiary, as erosion outstripped deposition in Michigan's continental environment; however, Quaternary glacial deposits are abundant. During this time, glaciers carved the Great Lakes and sculpted the present day landscape of lakes, hills, and swamps. Pine and spruce forests covered the region during times when the great ice sheets retreated. Fossils from this time indicate that mammoths, mastodons, musk ox, and giant beaver roamed the Quaternary lands.

[Auspex]

See where a garden rock can lead you?

Good job with the research; your first steps down what I hope will be a long

and gratifying path!

[crinus]

Perhaps you could give a bit more detail about the place you found it. I am a bit familiar with Michigan geology and maybe can help to be more specific. Without more information, I am going to venture to say that it is most probably Devonian and not Mississippian. I have never seen Mississippian rock in Michigan with that much stuff. It would not be unusual for Devonian in Michigan. It looks like coral with some bryozoa.

crinus

[MICHIGAN_MAN]

Auspex, yeah, it's a lot of fun trying to figure out what this is.

OK, so the smaller pieces are not branches from the bigger pieces? The bigger pieces are coral and smaller ones are a form of bryozoa?

It was found in the middle of the thumb, on the far west side of Sanilac county.

I think I know what the coral may be. Thamnopora limitaris I found an archive of Michigan coral fossils.

http://strata.geology.wisc.edu/mibasin/showfull.php?id=964

http://strata.geology.wisc.edu/mibasin/showfull.php?id=961

Is it common to find a piece of ancient sea bed this big? I was looking at the U of M archive and out of 198 coral specimens nothing was like this monster.

[Kentuckiana Mike]

Very nice find.

It looks like the coral Thamnopora that the famous University of Michigan professor Dr. Carl Rominger named.

See his fossil coral book on-line from 1876: http://www.archive.org/details/palontologyfos00romi He called it Favosites limitaris, description found on page 34-36 and plate XIII (page 190).

Coral fossils that size exist around the Louisville, Kentucky area. Visit the very nice website of the Falls of the Ohio State Park: http://www.fallsoftheohio.org/index.html to see more of the large corals that become visible when the Ohio River is low.

You might also check out publications by another University of Michigan researcher, Erwin C. Stumm. He was quite an expert on Paleozoic corals from the midwestern United States.

[MikeD]

OK, so the smaller pieces are not branches from the bigger pieces? The bigger pieces are coral and smaller ones are a form of bryozoa?

From the close up pics, it looks like a lot of the smaller pieces are also coral. There may be some bryozoans in there, but look like most of it is coral.

[crinus]

Auspex, yeah, it's a lot of fun trying to figure out what this is.

OK, so the smaller pieces are not branches from the bigger pieces? The bigger pieces are coral and smaller ones are a form of bryozoa?

It was found in the middle of the thumb, on the far west side of Sanilac county.

I think I know what the coral may be. Thamnopora limitaris I found an archive of Michigan coral fossils.

http://strata.geology.wisc.edu/mibasin/showfull.php?id=964

http://strata.geology.wisc.edu/mibasin/showfull.php?id=961

Is it common to find a piece of ancient sea bed this big? I was looking at the U of M archive and out of 198 coral specimens nothing was like this monster.

I am going to say that you probably have a Devonian piece that was brought down by the glaciers. The area where you found it is mainly Mississippian. The quarries in that area have nothing like that piece. The quarry at Rockport (Alpena County) has lots of rocks filled with coral. Not saying that is where your came from, just that the Devonian rock is loaded with stuff.

The University of Michigan archive site does not have a photo with a rock that is just loaded with stuff because I have chosen not to put one on the site. There are probably close to a million Michigan Basin specimens in the University collections and I am just scratching the surface. Right now I am mainly photographing the type and numbered specimens. It will take a couple of lifetimes to photograph everything and put it on the site. That is the goal.

crinus

[MICHIGAN_MAN]

OK, great! That archive was by far the best site I found for identifying Michigan fossils. Thanks for that!

[MICHIGAN_MAN]

Very nice find.

It looks like the coral Thamnopora that the famous University of Michigan professor Dr. Carl Rominger named.

See his fossil coral book on-line from 1876: http://www.archive.org/details/palontologyfos00romi He called it Favosites limitaris, description found on page 34-36 and plate XIII (page 190).

Coral fossils that size exist around the Louisville, Kentucky area. Visit the very nice website of the Falls of the Ohio State Park: http://www.fallsoftheohio.org/index.html to see more of the large corals that become visible when the Ohio River is low.

You might also check out publications by another University of Michigan researcher, Erwin C. Stumm. He was quite an expert on Paleozoic corals from the midwestern United States.

Yeah, I'm pretty sure that's it. Thanks for the links, very helpfull.

[MICHIGAN_MAN]

So I went out to the old rock pile today and knowing what I'm looking for now, I found another big sea bed rock. This one seams to have three types of coral in it and a lot of small stuff in the sediments. Some more Thamnopora, some Petoskey, and another one, looks like Petoskey. I don't know can Petoskey be White or Gray?

I was looking at the archive and think it might be this. It's hard to tell though.

http://strata.geology.wisc.edu/mibasin/showfull.php?id=210

[Tessy]

Can you get back to that farm field in Sanilac county? If you could...well, I'd be high-tailing it out there. You found some very cool stuff!

It seems odd that those boulder sized seafloor pieces could make it that far in glaciers with out getting chewed up.

Down here in the Detroit area I find lots of single corals that are quite weathered. I find them in quarried gravel and landscaping material, never get to find them on location.

Nice finds!

[Crinoid Queen]

hay nice bryzoans! I have found a few but they are nothign compared to that. welcome to the forum, by the way. Sorry it was so late i have been away for a little while

[MICHIGAN_MAN]

"Can you get back to that farm field in Sanilac county?"

Yeah, my house is in the middle of it. Lol No need to high-tale it out here. There is a pile of rocks behind my house where farmers have been dumping rocks for well over 100 years. The rocks get cough-up in the farm equipment and then you have to dig them out, put them into a loader and dump them into the rock pile. They are covered with dirt at that time, hard to tell what it is. The White spots on the rocks are damage from the equipment. There is a spot in the pile where there is a lot of dirt, rocks and large chunks of broken concrete mixed. That is where I'm finding them. There may be more, but I'll have to wait for spring see, it's all frozen solid right now. I just pick these up off the top.

Thanks for the replies and the welcome! I think this is a realy cool site. I just found a new hobby!

Edited March 8, 2010 by MICHIGAN_MAN

[Petoskeygal]

This is a chunk of several different corals. The first photo is of CLADOPORA. It is a fossilized form of finger coral. When it is fossilized in black "mud" it is very beautiful and makes beautiful polished cabachons. Some artists carve animal figures out of it.

You also have pieces of Michigan Petoskey, and Crinoid stems, plus possibly Horn Coral in there.

A very interesting conglomerate piece!

[glacialerratic]

Looks like a piece from around the NW Tip of the Mitt, dragged down by the last round of glaciation. I once walked on some huge boulders just like yours in a shale pit near Elsworth.