Paraspirifer from the Silica Shale

There are several large species of Spirifirid brachiopods found at Sylvania. The best known of these is Paraspirifer. It's typically a large shell, with the largest that I've found being the size of a Tangerine. Often you find them for sale at fossil dealers after they have been dipped in an acid bath to expose the pyrite replacement of parts of the shell.

Brachial Valve


Front


Pedicle Valve


Back


Profile


Most of the fossils I've found of Paraspirifer are of the large, round shells like the above. But some are different with a more compressed fold on the brachial valve so that it looks like a mohawk. The front view shows the effect most dramatically.

Brachial Valve


Front


Pedicle Valve


Rear


Profile



Based on the 1975 book by Robert V. Kesling & Ruth B. Chilman: Strata and Megafossils of the Middle Devonian Silica Formation: Museum of Paleontology, Papers on Paleontology, No. 8, pg. 110, pl. 22, 24, 25, 31 The above specimens are Paraspirifer bownockeri. I wonder if the second specimen, with the compressed fold area, represents a subspecies? Since I've found several specimens with this same feature it is not isolated to one oddball. I can't seem to locate any information online about variations in the Paraspirifer shell morphology but if anyone has some info, let me know.

Arthrocantha from Sylvania

During on visit to the Silica Shale dumps near Sylvania I was lucky enough to find some Arthrocantha fossils of my own.

This is a small Calyx with just the stumps of arms still attached.







This is a separate piece that shows part of the long arms that would be attached to the Calyx. Note the short spines at some of the arm junctions.



This species is well documented in the 1975 book by Robert V. Kesling & Ruth B. Chilman: Strata and Megafossils of the Middle Devonian Silica Formation: Museum of Paleontology, Papers on Paleontology, No. 8, pg. 166, 137, pl. 29, 37, 61, 62.

Platyceras on Arthrocantha

Arthrocantha crinoids were a common genera in the Silica formation and had a slew of protective spines to protect itself from predators. Still, some snails like Platyceras found their way onto the top of the animal. I'm not sure how the relationship worked, but the Platyceras would plant itself on top of the anal tube of the Crinoid and feed from it's waste. Considering that most specimens I've seen seem to cover the entire top of the Crinoid I'm not sure how the Crinoid survived.

These specimens were all purchased from a rock shop years ago.


Specimen #1






Specimen #2





Specimen #3

Botryllopora from Sylvania

A fairly rare Bryozoan from the Silica Shale at Sylvania is Botryllopora. It is found encrusting shells and other hard surfaces and has a star shaped look to it. Here it's covering part of a Strophodonta shell.




This is a different shell where the Bryozoan has colonized a flipped over Strophodonta shell.


It even grew onto the other side at one point, maybe the shell got flipped again?




This Bryozoan reminds me of a similar looking genera called Constellaria that is found in Ordovician aged rocks.


I'm labeling my specimens Botryllopora socialis based on the 1975 book by Robert V. Kesling & Ruth B. Chilman: Strata and Megafossils of the Middle Devonian Silica Formation: Museum of Paleontology, Papers on Paleontology, No. 8, pg. 62, pl. 18.

Fistuliporoid Bryozoans from the Silica Shale

I'm sure I've mentioned before about how difficult it can be to ID some Bryozoans beyond the Family level. Such is the case with some Fistuliporoid Bryozoans that I've found in the Silica shale.

Some form finger like branches


Others, massive colonies




Still others colonize Brachiopod shells




Without thin sections both perpendicular and parallel to the grain of the colony, I'll never be able to truly ID these even to a genus level. So they remain within my collection simply labelled "Fistuliporoid Bryozoan".