Differentiating Ordovician Stromatoporoids?

[JUAN EMMANUEL]

So I have been looking at my collection and it baffles me whether these two specimens are the same species with just different growth forms due to their deposition environments or are they entirely different species from each other? These stromatoporoids both come from the same locality (Streetsville, Mississauga, Ontario) in the Upper Member of the Georgian Bay formation, late Ordovician.

 

Can anyone provide me with any PDF on late Ordovician stromatoporoids so I can nail down the differences between Stromatocerium and Labechhia? 

 

On the site where I collected these, I have also found mounding round stomatoporoids ranging around 4 inches to over 1 ft in diametre. I think this must be Stromatocerium. 

With the stromatoporoid with the prominent mamelons I have found it encrusting Prismostylus sp. specimens on the locality (what an odd association). This stromatoporoid, from my experience with the locality, usually just grows over the size of an open hand. Is this Labechia, the one with prominent mamelons?

[Tidgy's Dad]

I have a Wenlock Labechia. 

See how you think it compares.

Sorry, but the photos are a bit rubbish, but may help a little.

2.8 x 1.9 mm. 

Labechia does have mammelons and is an encruster.