Odd tabulate coral from lower Michigan glacial drift

[LisaL]

Hello, everyone,

 

I could use some help with this odd little tabulate coral I found yesterday in an old gravel pit in southwest Michigan. I can't guess at a formation or age since it's glacial debris, but the things I find range from possible Ordovician (rarely) all the way to lower Mississippian. I think it must be either Devonian or lower Carboniferous.

 

When I first picked it up, I thought it was just another type of Favosites, given the corallite shapes and what turned out to be large mural pores (towards the left) when enlarged: (EDIT: TqB has suggested parasite traces for these holes I was calling 'mural pores!')

 

But on the other end, the corallites are showing what I thought were curved, incomplete tabulae like Michelinia, but found out after talking with @TqB that they may be funnel-shaped.

 

 

 

 

I forgot to include a size scale, but the corallite diameters range from about 2 mm to just under 4 mm.

 

 

 

 

We're having trouble coming up with cerioid infundibuliform tabulate corals that might be possible for Michigan, and Tarquin suggested that the coral experts here might have some ideas.

 

Many thanks!

Lisa

[TqB]

It's hard to interpret what the tabulae are up to, but they're at least strongly domed (hence the circles in the transverse sections). 

The longitudinal section seems to show near vertical walls for at least some of them, Syringopora style.

 

Not sure about the pores - there seem to be at least some connecting the corallites, but the ones going vertically into the walls do look like parasitic borings found in other Palaeozoic corals.

 

It may be something obvious that we're missing but it doesn't seem to relate to any of the usual suspects.

 

One coral that has a very similar form as far as we can tell is Bayhaium, but that's Permian from California.

(Images from Langenheim & Mc Cutcheon, 1953,  Bayhaium merriamorum, a New Permian Tabulate Coral from California.

 

Edited March 9, 2021 by TqB

[TqB]

This looks a promising characteristic if it is indeed family Roemeriidae.

If it does turn out to be one, they're apparently unrecorded from the American continent apart from the Permian Bayhaium of California/Nevada. Very well known from Europe and Australia though.

We need a specialist.

 

"Tabulae infundibuliform… in places elongated proximally to form a syrinx, which may divert from the axis to a mural pore so that communication is obtained between the tubes of neighbouring corallites". (Treatise F656)

 

(A syrinx being the tubular continuation of an infundibuliform (funnel shaped) Syringopora type tabella.)

 

 

Or possibly:

 

 

 

Edited March 10, 2021 by TqB

[TqB]

We've looked at the favositid Syringolites huronensis Hinde (Manitoulin Island, L. Huron)  as a glacially feasible candidate but it seems much too regular.

It essentially has favositid tabulae elongated to form a tube right down the centre. So, although it has been included in Roemeria in the past, its structure is importantly different as the tubes don't diverge to the pores at the sides.

Roemeria resembles Syringopora in this which is a fundamental ID characteristic (if you can see it!).

 

Compare this old drawing of a definite roemeriid, probably Roemeripora nowadays, with my photo above.  

 

While Syringolites huronensis  (from Manitoulin Island, L. Huron) looks like this:

 

Edited March 13, 2021 by TqB

[TqB]

@LisaL has just contacted a tabulate specialist and he agrees that it is a roemeriid, resembling Roemeripora.

 

Lisa's update here: 

http://www.thefossilforum.com/index.php?/topic/113683-roemeriid-a-new-family-of-tabulate-corals-in-the-us/

[oyo]

On 3/10/2021 at 12:41 PM, TqB said:

This looks a promising characteristic if it is indeed family Roemeriidae.

If it does turn out to be one, they're apparently unrecorded from the American continent apart from the Permian Bayhaium of California/Nevada. Very well known from Europe and Australia though.

We need a specialist.

 

"Tabulae infundibuliform… in places elongated proximally to form a syrinx, which may divert from the axis to a mural pore so that communication is obtained between the tubes of neighbouring corallites". (Treatise F656)

 

(A syrinx being the tubular continuation of an infundibuliform (funnel shaped) Syringopora type tabella.)

 

 

Or possibly:

 

 

 

Good work.