Coral ID from Michigan needed

[AstroRaptor56]

I found these pieces over past year and half and have just gotten around to IDing them. I can’t find anything on the internet or my book on what these are. They are from the Mississippian as I’m from west Michigan. It seems they attach to things as oneI found on a horn coral. One in the picture seems to have shell on the bottom as well. An ID would be awesome because these have been a headache for me! Thank you!

Edited June 20, 2020 by AstroRaptor56

[DPS Ammonite]

The look sort of like Palaeacis coral.

 

http://www.thefossilforum.com/index.php?/topic/24399-lake-jacksboro-pennyslvanian/&do=findComment&comment=267025

 

Photo sent to TFF member Indy: source unknown.

 

 

It appears that they occur in the Mississippian and Pennsylvanian Ages per Fossilworks: 

http://fossilworks.org/?a=taxonInfo&taxon_no=

[TqB]

I agree Palaeacis looks good but Microcyathus  is a possible ID. They're probably both family Palaeacidae and many now regarded as Microcyathus have been called Palaeacis in the past. Both occur in N. America, I don't know about Michigan though.

There's a good 1983 summary of N. American and European species here by John Nudds - I haven't looked for more recent stuff yet:

The Carboniferous coral Palaeacis in Ireland

 

According to the Nudds paper, the perforate/imperforate wall is a critical ID feature so sections may be needed, though DPS Ammonite's photo does look perforate and yours may well be.

 

Main differences (according to the Treatise):

 

Microcyathus: has a holotheca (outside layer surrounding all corallites

                    discoid, adherent

                    aperforate inner wall

 

Palaeacis: no holotheca

               wedge shaped, adherent in young stages

               perforate inner wall

 

 

Tabulates are awkward and these have also been regarded as sponges! 

 

Microcyathus cyclostoma of mine from Scotland. A bit worn as it's from beach shingle - these occur attached to bits of crinoid, coral or shell. Filled with sediment so not much use for the perforate/imperforate feature...

Scale in mm

 

Microcyathus from Treatise:

 

Palaeacis from Treatise:

[AstroRaptor56]

5 hours ago, TqB said:

I agree Palaeacis looks good but Microcyathus  is a possible ID. They're probably both family Palaeacidae and many now regarded as Microcyathus have been called Palaeacis in the past. Both occur in N. America, I don't know about Michigan though.

There's a good 1983 summary of N. American and European species here by John Nudds - I haven't looked for more recent stuff yet:

The Carboniferous coral Palaeacis in Ireland

 

According to the Nudds paper, the perforate/imperforate wall is a critical ID feature so sections may be needed, though DPS Ammonite's photo does look perforate and yours may well be.

 

Main differences (according to the Treatise):

 

Microcyathus: has a holotheca (outside layer surrounding all corallites

                    discoid, adherent

                    aperforate inner wall

 

Palaeacis: no holotheca

               wedge shaped, adherent in young stages

               perforate inner wall

 

 

Tabulates are awkward and these have also been regarded as sponges! 

 

Microcyathus cyclostoma of mine from Scotland. A bit worn as it's from beach shingle - these occur attached to bits of crinoid, coral or shell. Filled with sediment so not much use for the perforate/imperforate feature...

Scale in mm

 

Microcyathus from Treatise:

 

Palaeacis from Treatise:

Thank you for the information! This helps me out so much!

[AstroRaptor56]

11 hours ago, DPS Ammonite said:

The look sort of like Palaeacis coral.

 

http://www.thefossilforum.com/index.php?/topic/24399-lake-jacksboro-pennyslvanian/&do=findComment&comment=267025

 

Photo sent to TFF member Indy: source unknown.

 

 

It appears that they occur in the Mississippian and Pennsylvanian Ages per Fossilworks: 

http://fossilworks.org/?a=taxonInfo&taxon_no=

It does look a lot like that, thank you!