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Monica

Bryozoan or Stromatoporid at Mimico Creek

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Monica

Hello once again!

 

Yesterday when I went out with Viola to Mimico Creek in Toronto (Georgian Bay Formation, Upper Ordovician), I found an interesting piece and I'd like your thoughts regarding its identity.  The dome-shaped object in the photos below has bumps all over it, and there are tiny pores throughout, so I was wondering if you think it's a bryozoan or perhaps a stromatoporid (apparently Labechia huronensis is a bumpy-looking stromatoporid that can be found in the Georgian Bay Formation, but MANY bryozoans can be found here, too - including on this piece of rock! - so I'm not sure which it is).

 

"Front" of specimen:

DSCN1675.thumb.JPG.49b2e5836d81a80501e3fa544638a53e.JPG

 

"Back" of specimen:  What is the conical-shaped, segmented item in the upper right-hand corner, by the way?

DSCN1676.thumb.JPG.6022e4b4a06718314cb0211bea891e05.JPG

 

Closer views of the bumpy, dome-shaped object:

DSCN1677.JPG.f25a470b423b9d9df605ae7e9faa4a2e.JPGDSCN1678.JPG.6b6087805ec8bd0d2dc029f397f971dc.JPG

 

Thanks for your help!

 

Monica

 

 

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Archimedes

Hi looks like some nice Bryozoans and on the back side is a nice Tentaculites

 

DSCN1676_thumb_JPG_6022e4b4a06718314cb0211bea891e05.jpg.08905889ea7f0ddb38f61014a876f7da.jpg

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Rockwood

Pretty sure that's a tabulate coral.

Agreed on the  Tentaculites.

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piranha
1 hour ago, Monica said:

...bumpy, dome-shaped object...

 

 

Compare with the trepostome bryozoan: Stigmatella

 

figure from:

 

Hessin, W.A. (2009)
South-Central Ontario Fossils: A Guide to the Ancient Marine Life of the Region.
Cobourg, Ontario, Canada, 286 pp.

 

IMG.jpg.39f804cc1ac2e0e78f37f5477111ae0b.jpg

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Rockwood

Bumpy ? 

Guess I don't see the same. 

Oh. On a slightly larger scale. Could be.

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fifbrindacier

I agree with Piranha. Nice find.:)

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abyssunder

I'm thinking about an assemblage of Cornulites, bryozoan encrusting a stromatoporoid. :headscratch:

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doushantuo

KEY

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Monica
4 hours ago, Archimedes said:

Hi looks like some nice Bryozoans and on the back side is a nice Tentaculites

 

DSCN1676_thumb_JPG_6022e4b4a06718314cb0211bea891e05.jpg.08905889ea7f0ddb38f61014a876f7da.jpg

 

4 hours ago, Rockwood said:

Agreed on the  Tentaculites.

Hi there!

 

Tentaculites sp. is pretty exciting for me since I've never found one before!  In fact, I only just heard of their existence about a month ago when I was in contact with a fossil-hunter out in the London, Ontario area!!!  The book that I've been using to try to get some idea of what I've been finding in my area doesn't include any discussion about Tentaculites sp. so I didn't even think that it would be a possibility, but now that you've mentioned it, that little guy (circled in yellow) does indeed look like one!  Thanks for chiming in!

 

Monica

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doushantuo

tentaculites are important in Devonian biostratigraphy!!!

Some bioevents are named after them

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Monica
3 hours ago, piranha said:

 

 

Compare with the trepostome bryozoan: Stigmatella

 

figure from:

 

Hessin, W.A. (2009)
South-Central Ontario Fossils: A Guide to the Ancient Marine Life of the Region.
Cobourg, Ontario, Canada, 286 pp.

 

IMG.jpg.39f804cc1ac2e0e78f37f5477111ae0b.jpg

Hi!

 

That does look like a decent match to my specimen, and since Stigmatella sp. is indeed found in the Georgian Bay Formation, then that is probably what I have.  Thanks for helping me out!

 

Monica

 

PS - I actually have a hard copy of the book you cited, but there are so many bryozoans listed that it's all a bit of a blur to me.  I was also secretly hoping that I had found a stromatoporid since I've not yet found one, but it's time for me to face the facts - I believe that what I found is indeed a nice-looking little bryozoan :)

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doushantuo

Use PDFs:they are searchable

I've just downloaded Ulrich & Bassler to take a peek at Stigmatella.

Confusingly enough,Stigmatella also seems to be something else

"Zoarium variable, ranging from incrusting to irregularly massive
and ramose. Zocecia angular, rounded, or irregularly petaloid, the
shape depending upon the presence (or absence ) of mesopores and
the number of acanthopores. Typically the zoarial surface exhibits
at regular intervals maculae or spots composed of mesopores,
although in some species the usual monticules or clusters of large
cells occur. Acanthopores always present but variable in number,
intermittent, developed chiefly in narrow zones, sometimes inconspicuous
but more often so numerous as to give the surface a decidedly
hirsute appearance. Mesopores, when present, developed in mature
region only, their number being variable even for the same species.
The zocecial tubes have thin walls in the axial region and these
become but slightly thickened in the peripheral region wdiere a few
unusually delicate diaphragms are inserted. In vertical sections the
walls exhibit at rather regular intervals in the peripheral region thickening's
somewhat similar to those occurring in Stenopora. These
thickenings occur approximately at the same height in the walls, and
tangential sections through these zones give the full development of
acanthopores. Minute structure of walls as shown in tangential sections,
of the type that characterizes the Heterotrypida.
Genotype.—Stigmatella crenulata new species. Richmond formation

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Monica
1 hour ago, abyssunder said:

I'm thinking about an assemblage of Cornulites, bryozoan encrusting a stromatoporoid. :headscratch:

Hi abyssunder!

 

I would LOVE to have found something other than a bryozoan, but I think piranha found a match to my specimen, and I believe that it is indeed the bryozoan Stigmatella sp.

 

I was just wondering about your suggestion regarding Cornulites sp. - do you think that's what I have in the upper right-hand corner of the "back" side of the rock?  If so, how can I tell between that and Tentaculites sp.?  Or should I just label it as "Class Tentaculita" since both genera belong to that class?  Also, do you see any other candidates on my rock that can also be given this label?

 

Thanks so much!

 

Monica

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Monica
4 minutes ago, doushantuo said:

Use PDFs:they are searchable

I've just downloaded Ulrich & Bassler to take a peek at Stigmatella.

Confusingly enough,Stigmatella also seems to be something else

Hi doushantuo!

 

If it's any help, the names given in my book are as follows:

 

Stigmatella personata lobata Dyer

Stigmatella vulgaris Parks and Dyer

 

Monica

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piranha

Hessin 2009 does not mention Tentaculites, instead describes Cornulites flexuosus from Georgian Bay.

 

IMG.jpg.bf3071d17477c80634f65128a0c9061d.jpg

 

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doushantuo

cornulites

j.1096-3642.2007.00300.x.pdf

Liam's thesis on Silurian problematica is a good read BTW

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doushantuo

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doushantuo

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Monica
5 minutes ago, piranha said:

Hessin 2009 does not mention Tentaculites, instead describes Cornulites flexuosus from Georgian Bay.

 

IMG.jpg.bf3071d17477c80634f65128a0c9061d.jpg

 

Hello again!

 

You are correct - Cornulites flexuosus is indeed mentioned in the book - thanks for the heads-up!  My specimen looks a tiny bit different - each segment almost seems to have a zig-zag pattern on its wider side - but that could just be my eyes playing tricks on me and/or the fact that it's not the best-preserved specimen.  It's interesting that Hessin (2009) states that these animals "are considered by most paleontologists to be an extinct type of calcareous tube worm (annelid)" but that "the walls of the tubes are thick with a cellular calcium carbonate structure which has led some researchers to believe that they are a type of stromatoporoid or calcareous hydroid."  So, maybe I did find a stromatoporid? :P  Anyway, you've likely found out my specimen's identity since it's been found in the Georgian Bay Formation before, so thanks once again!!!

 

Monica

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Monica
14 minutes ago, doushantuo said:

cornulites

j.1096-3642.2007.00300.x.pdf

Liam's thesis on Silurian problematica is a good read BTW

 

10 minutes ago, doushantuo said:

 

9 minutes ago, doushantuo said:

 

6 minutes ago, doushantuo said:

Hi again, doushantuo!

 

Thanks for all of the links!  I'll definitely have a look through them when I have the time since I'm pretty excited that I've found something new (for me) from the area - hooray!!! :yay-smiley-1:

Monica

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doushantuo

those pdf are there for everybody,not just for you:P

I'm looking at the miscellanous Stigmatellae definitions,but acanthopore and mesopore distribution..

gee,dunno.

the taxonomy might be obsolete.

I know of several cladistic analyses of Ordovician bryozoa....

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doushantuo

oh yeah:nice finds BTW.:P

The odds  of(for?) finding something like that near where i live are the same as Sheldon dissing the roommate agreementB)

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