Unknown Coral

I Cut and polished this saggital cut of the coral

This is a very highly processed scan of the axial region

Explanation with initial posting 5/20/03:

I have not identified this coral. It is in a core from the West Franklin Limestone
in western Kentucky (Webster County). The age is earliest Late Pennsylvanian
(early Missourian). Based upon gross similarities to descriptions and illustrations
in the Treatise on Invertebrate Paleontology (Part F Coelenterata Supplement 1,
1981), I concluded initially that it belongs in the rugosan Family Arachnophyllidae,
most closely resembling the genus listed as "?Craterophyllum" (p. F217). This
genus is reported only from the Upper Silurian to Middle Devonian, however, and
the family only from Lower Silurian to Middle Devonian.

My specimen is not identical to the illustrated specimen of ?Craterophyllum
volcanium in which more of the tabularium is free of septa. Several of the
arachnophyllid genera are listed in the Treatise with preceding question marks,
and come from remote locations. Review of the section on the family suggests it
is a poorly known group, giving me license to believe it really could be a
representative of that family.

I found a reference to Craterophyllum in "Carboniferous" strata in Nebraska by
Barbour, 1911 (NGS Bull. 4-3). In the first version of the coral volume of the
Treatise published in 1956 it lists that reference as "non Barbour, 1911," meaning
that Barbout hadn't really found Craterophyllum.

My additional comments posted 5/23/03, after hearing from several readers, whose
input has been helpful (thank you!):

The taxon Barbour (1911) referred to erroneously as Craterophyllum is apparently
Pseudozaphrentoides, which was synonymized with Caninia in the 1956 Treatise
volume on corals, but is listed as a separate genus in the 1981 edition.
Pseudozaphrentoides is in the suboder Caniniina, family Cyathopsidae, and has
wide, flat tabulae and narrow dissepimentarium, both features at odds with my
specimen. At least they are Carboniferous taxa.

I found that significant differences in similar taxa often relate to features of the
axial region, so I prepared a longitudinal section of this specimen. The scan is
in black and white following heavy processing to bring out details of axial structure.
The color longitudinal section is somewhat eccentric, missing the column.

The longitudinal section shows the axial region is made up of inner and outer
tabularium. Tabellae (short, more or less horizontal partitions similar to tabulae) of
the axial series (inner tabularium) project upward sharply to form a series of cones
making a column. Tabellae of the periaxial series are convex upward.

Except for the cones in the column, the tabularium floor does not seem to decline
abaxially (away from the axis). This may or may not exclude it from the
Aulophyllidae (suborder Aulophyllina). However this is not a pronounced feature in
my specimen, and it does have the inner coned area with tabellae steeply inclined
abaxially, so I believe the coral is in the Aulophyllidae, all characters considered.
The family ranges from Lower Carboniferous to Lower Permian.

Among aulophyllids, Auloclisia may be close. Aulophyllum itself lacks the coned
tabellae in the column. Possibilities suggested by readers include Dibunophyllum,
but the well-defined conical column in my taxon seems to eliminate that genus
from consideration. The very broad dissepimentarium in my specimen seems to
eliminate Noekoninckophyllum.

However, I am not sure of the significance of the broad, everted dissepimentarium.
Could this be a ecophenotypic variation? The carbonate sediment was muddy and
presumably soft. An abruptly expanding the dissepimentarium might have been a
mechanism to prevent it from sinking into a soupy substrate as it grew larger and
heavier. The fact that after expanding it narrows again might support this
interpertation.

Someone suggested it might be Geyerophyllum. However that is in a different
suborder (Lithostrotionina), which are all compound.

I wish someone would make a key to aulophyllid indentification that would
eliminate the need to wade through the generic diagnoses in the Treatise, all of
which sound alike!

Comments on 5/25/03:

Restudy of the Treatise shows I missed a heading. Geyerophyllum is in the
suborder Lonsdaleiina, not Lithostrotionina. Lonsdaleiina may indeed be solitary,
so Geyerophyllum cannot be excluded for that reason. However, the dissepiments
of Geyerophyllum seem to be quite irregular in size and are convex toward the
axis (a type called lonsdaleoid). In my specimen, the dissepiments are regular in
size and shape and are concave toward the axis (called "concentric").

Sestrophyllum has been reported from limestones of similar age in Iowa (the
Worland Limestone, Bethany Falls Limestone, and possibly the Winterset
Limestone) by Pope (in Heckel and Pope, 1992 Field trip guidebook for the North
Central Geological Society of America meeting in Iowa City, IA: Guidebook Series
No. 14, Iowa Dept. Natural Resources). Interestingly, this genus is in the same
auloporid subfamily (Dibunophyllinae) as Dibunophyllum, which had been
suggested as a possibility for my specimen.

The Treatise describes Sestrophyllum as having slender, conicocylindrical
corallite and narrow dissepimentarium. Like Dibunophyllum, a narrow dissepi-
mentarium seems to exclude Sestrophyllum from consideration. But farther down
the diagnosis, it says that Sestrophyllum may have everted calicular platform,
which is probably the correct way of saying what I described as "everted
dissepimentarium." Note "may have," possibly verifying my suspicion that this is
an ecophenotypic variation.

Sestrophyllum has a cardinal septum that is not shorter than other septa, which
seems to be true for my specimen. Minor septa are weaker than major septa--also
true of my specimen. Also, the septa in Sestrophyllum may become discontinuous
abaxially. This character is not described for many corals in this group, and it is a
feature that caught my attention almost immediately in examining my specimen.
Also, in the subfamily Dibunophyllinae, the axial tabellae are steeply inclined, and
interfinger with the periaxial tabellae--features of my coral that are visible in the
axial section I posted. I am therefore leaning toward Sestrophyllum. This is in spite
of the fact that the illustrations in the Treatise do not strongly resemble my
specimen. Ya gotta read!

Any more comments?

Please email with your comments to:
Norman R. King
nking@usi.edu
altamont@insightbb.com
________________________________________

Viewer Comments #1

Craterophyllum eventually wound up in the genus Pseudozaphrentoides. R. F.
Diffendal, Jr., did an MS thesis on this coral in 1964. There are also a couple of
theses by Gordon Baird and Robert O. Schrott that delved into Pennsylvanian
corals in Nebraska. Craterophyllum, I think, went in a rather circuitous route to
end up in Pseudozaphrentoides, spending some time in the genus Caninia, and
I think another genus, the name of which I do not recall at the moment.

You can probably track this coral down through the paper: Cocke, J. M., 1970,
Dissepimental Rugose Corals of Upper Pennsylvanian (Missourian) Rocks of Kansas:
University of Kansas Paleontological Contributions, Article 54 (Coelenterata 4). I
would guess that your coral either belongs in Neokoninckophyllum, Geyerophyllum,
or Dibunophyllum. Cocke gives ranges for some of the species of these.
________________________________________

Norman R. King
nking@usi.edu
altamont@insightbb.com

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