Silurian and Devonian Corals

Here are some fossils I have found in the Devonian/Silurian period layer or Jeffersonville/Louisville limestone. These fossils were found in Jefferson County, Kentucky.



First is a cross section of a Stromatoporoid sponge.



This next fossil is a cross section of Siphonophrentis elongata horn coral. I normally find this in reddish-brown-white rock but this one is light gray. On the other side it still has texture of the horn coral surface preserved.

Here is a polyp jutting out of the surface of a Heliolites coral.

Here are some pipe organ corals. I have not found a piece this big before. I have been using a ruler I got at the Cincinnati GeoFair 2009 from Kent State University exhibit. It is quite handy.

I am not sure what this next plate is called. It could be Heliolites coraL.

Here is a hemispherical shaped coral that might be some sort of Heliolites.

Another coral I am not sure what it is called. It has some distinctive growth rings.

Here is a Favosites or honey comb coral.

Silurian Horn Coral - A Mystery Solved

Recently, I have been collecting Silurian corals. I found this one which has several interesting aspects. One it shows four horn corals that have budding out of the main one and another coral that has budded out of its base. Second, the smaller horn coral at the base has holdfasts coming out of it.

It is this second point that merits my study today. I have been finding small horn corals with marks on their horn exterior surface and sometimes I find "spines" intact (see green arrows on first picture). At least that is what I assumed till I found this specimen. My thought was they were spines that kept snails from moving up the horn wall (corallum?) to the calice or horn rim. They reminded me of spines on crinoid calyx. I have found what appear to be snail boring holes or track lines on the corallum on other horn corals, so it made sense.

This fossil shows one of them intact that it is holdfast to anchor the smaller horn to the larger horn. So these protrusions were used as anchor lines to bond the corals together in this case.

These pictures where taken quickly under an incandescent light and I was not using a tripod. I will post more about this fossil later since it shows a good example of the budding reproduction process used by horn corals.

Reading up, the book calls the Silurian period, the "Age of Corals". From what I can tell the official coral of that period should be the Halysites chain coral. The Fossils of Ohio book identifies the following phylum has Silurian: Amplexus, Cyathophyllum, Holophragma, Rhegmaphyllum, and Zaphrenthis.

Unknown Silurian Brachiopods

Here are some unknown Silurian brachiopods found in the Louisville limestone, Jefferson County, Indiana.

Paraspirifer bownockeri Brachiopod with Hederella Bryozoan

Here is a brachiopod fossil that I sandblasted. It is from Sylvania, Ohio, USA in Lucas County. This brachiopod is called Paraspirifer bownockeri (Stewart, 1927) from the Silica Formation. Also note the encrusting Hederella (Hall, 1883) bryozoan (blackish root looking material). Fossil dates to the upper middle Devonian Period (Givetian Stage).

Devonian Wood: Callixylon Fossil

Devonian wood fragments of an Archaeopteris progymnosperm. The wood part is also referred to as a Callixylon. These fragments were found in Bullitt County, Kentucky at road cuts.

This specimen was found in the New Albany shale. The Callixylon log maybe floated into this area from Pennsylvania or New York where it sank and was covered. The weight of layers building up over time flattened the wood pieces. Heat and pressure coalified or vitrinized the wood.

Caryocrinites Silurian Crinoid

Here are some Silurian period crinoid calyx plates from the Louisville limestone. It is called Caryocrinites and was found in Jefferson County, Kentucky.

Sandblasted Devonian Brachiopod

On June 17, 2009 I highlighted a Devonian Mediospirifer brachiopod. Today, I revisit this brachiopod after sandblasting the matrix off of it revealing more details of the encrusting Aulocystis corals and bryozoan. You can now see the full shape of the interlinking Aulocystis.

Close up of a cleaned up Philhedra inarticulate brachiopod.

Equisetum: The Living Fossil Plant

Visiting my cousin where I was using the sand abrasive unit to clean fossils, I toured his plant garden and came upon this. I thought it was some sort of bamboo but he told be it is a living fossil. This plant is known as Equisetum hyemale or common names Horsetail reed or pewterwart. It was known for its high silca content making good for cleaning utensils and clean wounds.

The plant is a desendant of Calamites which are some fossils shown in this entry. These fossils were found in West Virginia. They are from the Pennsylvanian period.

The cone or sporangim is used to disperse microscopic spores.

Neat cell pattern on cone.

Imprint of a Calamites leaves.

Here is a stem pattern that can be seen in a smaller version on the Equisetum.

Here is something that was on one side of the rock that looks like a bark pattern. The rock is brown but this fossil has been treated with a glaze that makes it shine.

A brownish rock that has Calamites imprints that has been glazed.

The last two pictures are of leaf imprints.

Devonian Clam/Brachiopod/Cornulite

Here is a Devonian clam and brachiopod fused together. They were found in the Jeffersonville Limestone in Clark County, Indiana. It looks to be that the clam and the brachiopod did not interact together. Looking at just the brachiopod side we see a Cornulites attached to one of the shell ridges and at the hinge point of the shell a hole. It is possible that a snail bore into the brachiopod shell.

Signs of beekite are on both sides of the brachiopod shell.