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Bryozoans Vs Corals


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#1 Maniraptoran

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Posted 02 September 2011 - 02:06 PM

how can i tell the difference between fossilized bryozoans, corals, and calcerous algae, and stromatoporoids? i have mountains of each in my collection but i cant tell for the life of me which is which.

#2 crinus

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Posted 02 September 2011 - 09:22 PM

Try using this website to ID many of your Michigan fossils. There are almost 1500 photos with ID. It will also answer your vertebrate question.

Michigan Basin Fossils

crinus

#3 erose

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Posted 02 September 2011 - 11:44 PM

how can i tell the difference between fossilized bryozoans, corals, and calcerous algae, and stromatoporoids? i have mountains of each in my collection but i cant tell for the life of me which is which.


Size of the small chamber the animal lived in is the best guide. The vast majority of bryozoans all have openings that are just fractions of a millimeter. Think pin-hole in size. Most colonial corals start around a millimeter and up. Stromaoporoids are more like bryozoans and you probably need to see them in section for best ID. All three are totally different animals as well. Also don't be misled by magnified images in books and field guides. A bryozoan magnified ten times could look like a coral. Years ago I took the time to adjust some images from books on the copier to all be at full scale. It was an ah ha moment when I realized I had things quite out of scale in my minds eye.

Edited by erose, 02 September 2011 - 11:48 PM.


#4 Shamalama

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Posted 03 September 2011 - 07:58 PM

Erose is correct, Bryozoans and Corals superficially look similar but the size of the pores that they lived in will help you separate them. Also, Bryozoans tend to form either small rounded, mound shaped colonies or thin delicate fan or finger shaped ones. Stromatoporids and Calcareous Algae form similar shapes and you would need a micoscope to tell them apart. Generally if there is some sort of shape to the underside (wrinkled) then I consider it a stromatoporid.
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#5 glacialerratic

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Posted 04 September 2011 - 06:44 AM

I've found a few stroms up here that are from the Petosky Stone horizen, and are super hard. The layers that form the stroms are what make these cool. No photos, I need to polish them.
There are also rough stroms up here. The give away on each one are the bumpy surface structures (don't know the proper terminology). Sometimes you have to look hard, but they are there:

Attached Thumbnails

  • strom.gif


#6 piranha

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Posted 04 September 2011 - 01:31 PM

I've found a few stroms up here that are from the Petosky Stone horizen, and are super hard. The layers that form the stroms are what make these cool. No photos, I need to polish them.
There are also rough stroms up here. The give away on each one are the bumpy surface structures (don't know the proper terminology). Sometimes you have to look hard, but they are there:


Nice Tim!

That is the nifty stromatoporoid Parallelopora winchelli. The terminology for the 'bumps' is mamelons.
Attached is a six inch example (front & back) from the Gravel Point Formation of the Traverse Group.


Parallelopora winchelli.jpg

#7 glacialerratic

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Posted 04 September 2011 - 07:58 PM

That's very nice, piranha!

And it's even from the Michigan Basin! Thanks for the terminology lesson.

#8 OhioDave

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Posted 05 September 2011 - 06:45 PM

Hmmm the rule of thumb for me, at least for Ordovician fossils, is "bryozoans=boring" and "corals=cool". I've always been intrigued by the cross sectional detail in both solitary and colonial rugose corals, which is often lacking in the bryozoa.

I have a lot of this tabulate coral, trying to figure out what I could do with it. Section it maybe?

http://www.uky.edu/O...es/tabulate.jpg



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