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JUAN EMMANUEL

Streetsville, Mississauga Reef Fossils

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JUAN EMMANUEL

Hello, I want to put together some pics of some of the reef material that I have found in Streetsville, Mississauga, Ontario on the banks of the Credit River. It is now winter and I am missing the warm days in which I can go and wade in the warm waters of the river for fun. I just want to compile and share some specimens that whose photos I have not shared with. 

All the fossils belong to the Georgian Bay formation, Upper Member, which is late Ordovician in age. 

First is the common coral that displays an enormity of growth forms, Favistella alveolata (Goldfuss, 1826). 

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JUAN EMMANUEL

This is the biggest Favistella alveolata I have found this summer. I have found bigger, incomplete fragments this size so something tells me this coral can get a lot bigger than what I am showing here. It's the size of a hamburger if you hold it with 2 hands!

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JUAN EMMANUEL

Then there's the calcareous algae Prismostylus sp. (I am not sure what the exact species name yet; the fossil was called Tetradium approximatum). 

This below is a small fragment, roughly around 3.5 in long. 

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This one below was the first Prismostylus I found this summer. 

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The biggest Prismostylus colony I have found this summer. I have yet to photograph it nicely. It is around 20 cm or longer at its length. 

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JUAN EMMANUEL

The third fossil that dominates this reef community is the sponge Stromatocerium huronense (Billings, 1865). Here are some of its growth forms. Some colonies of this sponge can grow up to 2 ft wide or more. 

This fossil is approximately 15 cm across. 

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An unusual specimen, 10 cm across, with a small Favistella alveolata colony growing on it.

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JUAN EMMANUEL

A small colony of Stromatocerium I found. I recall it was the smallest specimen I found that I was able to carry home on that hunting trip. 

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I will post more pictures of other fossils soon other than these organisms that dominate the reef environment in Streetsville, Mississauga, Ontario. I also found a gastropods, Holtedahlina brachiopods, and lots of bryozoans.

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doushantuo

I'm horrifically biased,but those are pretty nice finds,JE

 

Prismostylus(Florideaphytean alga,"used to be" Tetradium:

The reassigment was made by Steele-Petrovich,who sure knows her Ordovician Canadian bioherms 

The presence or absence of "septa" depends on the degree of diagenesis

 

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useful info from the 1989 Yang thesis,which is basically unpostable(extremely muddy-looking and thus useless photographic 

documentation

 

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doushantuo

Having doubts about the taxonomy of Favistella (Dendrostella/Columnaria/possibly Synaptophyllum)

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Herb

I believe that Favosites  sp. does not have septum. Maybe Lyopora sp?

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Ludwigia

Nice finds! Thanks for sharing them. I have no doubts, but I'm also no expert on this fauna.

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FossilDAWG

Nice finds.  It's good to know the Streetsville reef is still at least somewhat accessible and hasn't been graded, ripwrapped, or otherwise destroyed as is all too common it seems.

 

I'm a bit surprised to see you are continuing to use "Favistella alveolata", as we discussed this a while ago in this thread.  The name for this coral has been Favistina calcina (Nicholson, 1864) since 1961, when Rousseau Flower revised this and many other Ordovician corals (New Mexico Bureau of Mines and mineral Resources Memoir 7).  "Favistella alveolata", the genotype of Favistella, was established by Goldfuss based on a specimen from glacial drift, collected in upstate New York.  As such, the source formation and even the age of the specimen is ambiguous, as Ordovician, Silurian, and Devonian rocks could have been the source.  Even worse, the specimen was described in very cursory and totally inadequate terms, by modern standards, and the actual holotype specimen has been lost so we can't even look at it to see what the actual diagnostic characters are.  Nicholson distinguished the Streetsville corals as a new species based on septal counts and, most importantly, the tendency of some corallites to become free from the mass of the colony and form rounded tubes not in lateral contact with other corallites.  When Flower (1961) was describing some New Mexico corals, he had to decide what genus to put them in, and so he had to consider what really distinguished Favistella from other corals.  After wrestling for a couple of pages over the problems posed by Favistella (no holotype to examine, really poor description in the literature, no way to know the age or source) he decided to restrict the name to the now lost holotype specimen, and create a new name, Favistina, based on a good specimen (with multiple thin sections) from a precisely known source.  You will see the name Favisella alveolata used in older papers, mostly in faunal lists in papers that are mostly concerned with geology and not paleontology.

 

Don

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JUAN EMMANUEL
5 hours ago, FossilDAWG said:

Nice finds.  It's good to know the Streetsville reef is still at least somewhat accessible and hasn't been graded, ripwrapped, or otherwise destroyed as is all too common it seems.

 

I'm a bit surprised to see you are continuing to use "Favistella alveolata", as we discussed this a while ago in this thread.  The name for this coral has been Favistina calcina (Nicholson, 1864) since 1961, when Rousseau Flower revised this and many other Ordovician corals (New Mexico Bureau of Mines and mineral Resources Memoir 7).  "Favistella alveolata", the genotype of Favistella, was established by Goldfuss based on a specimen from glacial drift, collected in upstate New York.  As such, the source formation and even the age of the specimen is ambiguous, as Ordovician, Silurian, and Devonian rocks could have been the source.  Even worse, the specimen was described in very cursory and totally inadequate terms, by modern standards, and the actual holotype specimen has been lost so we can't even look at it to see what the actual diagnostic characters are.  Nicholson distinguished the Streetsville corals as a new species based on septal counts and, most importantly, the tendency of some corallites to become free from the mass of the colony and form rounded tubes not in lateral contact with other corallites.  When Flower (1961) was describing some New Mexico corals, he had to decide what genus to put them in, and so he had to consider what really distinguished Favistella from other corals.  After wrestling for a couple of pages over the problems posed by Favistella (no holotype to examine, really poor description in the literature, no way to know the age or source) he decided to restrict the name to the now lost holotype specimen, and create a new name, Favistina, based on a good specimen (with multiple thin sections) from a precisely known source.  You will see the name Favisella alveolata used in older papers, mostly in faunal lists in papers that are mostly concerned with geology and not paleontology.

 

Don

Hi Don thanks for the input. Can you provide an access to the paper where it is called Favistina calicina? Is R.S. Bassler's "Faunal Lists and Descriptions of Paleozoic Corals" (1950?) out of date? That's where I got the name Favistella alveolata as there were pages describing the fauna of Streetsville in Mississauga. 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
   
 

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JohnBrewer

Beautiful examples!

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FossilDAWG

I'll see if I can dig out my copy of Flower's 1961 memoir and copy the relevant pages for you.  Bassler's paper precedes Flower's study and so uses older names.  Even so, he should have listed the coral as Favistella calcina.  However at the time some people thought that the growth form that distinguishes F. calcina (a mix of cerioid and phaceloid growth habit) was a result of growing in a muddy environment (the Streetsville reef has lots of shale interbeds indicating a high input of sediment, unlike the purer limestone deposits where corals are more often abundant), and so a pathology rather than a good species-specific character.  As a result, they considered F. calcina to be an environmental variant of F. alveolata.  Flower recognized a close relationship between Favistina (his new name for Favistella) and another coral, Paleophyllum, which has a strictly phaceloid growth habit (corallites are round tubes, connected by small spiny processes).  Corals such as Favistina calcina and the slightly older Favistina paleophylloides (found in Black River aged deposits) are intermediate between the fully cerioid and the fully phaceloid members of the lineage.  As such, the mixture of growth forms is a species-level character and not a pathology.

 

Don

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doushantuo

I think Jull revised some species in 1976(Geol.Mag.,payw.))(together with Nyctopora and Calapoecia).

 

 

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