Here is the mold and cast of the shell side by side.
The detail has been nicely preserved.
At the locality I was collecting the Mahantango is somewhat sandy and is referred to as the "Montebello sandstone". Much of the rock layers exposed are indeed sandstone of varying grain sizes but there are occasional thin layers of shale that represent rises of sea level called transgressions. Another theory is the facies (rock type) change is due to the settling of sediments within the local basin which leads to deeper waters.
Could it be loxonema? I was wondering as it seems similar, and I haven't seen a "paleozygopleura" anywhere.
ReplyDeleteActually, it should be labelled as Rhenozyga since that is what Paleozygopleura was renamed in 2008 (after being Loxonema for a while).... but I'm a little lazy. :)
ReplyDeleteI would really like your opinion. I found a large shell in some shale with an ammonite, trilobites and brachiopods in Fulton County. The shell has lines going vertically down it that are covered in bumps. Also the hinge has some line-like things going vertcally across it. Is it safe to call it Linoproductus, and if so Pennsylvanian in age? Hope you know!
ReplyDeleteThe trilobites have 6 to 7 axial rings with a smoth "border" around them, not ribbed like in phacops. The only complete one i have has about 10 thorax segments and a oval shapped glabella. Is it Ditomopyge?
ReplyDeleteIt could be Linoproductus but I would only be able to tell that by looking at it. Can you be more specific about where in Fulton County you found it? There is a small area of Pennsylvanian aged rock in the north west corner of the county but most of the rest is Mississippian through Silurian.
ReplyDeleteKind of in the western part of it, at the north end of a big hill (maybe sideling, or some other one) its kind of to the north. There really isnt a town or village next to the locality. I would say northwest, yeah. Theres even coal pieces exposed. I was thinking Conemaugh Group. If it helps any theres a creek right next to it.
ReplyDeleteThe shell doesnt look like Devonian shells. Its larger than anything else, about an inch and a half wide not from hinge to hinge. Hinge to hinge would be more like 3 inches. There are many bumps on it, all covering the shell. Fine ribs going vertically down shell. No large pedicles. The spines are near the edge in rows. Some lines are larger than others. Its a little rinkled in parts. I found it in dark gray (almost black) shale.
ReplyDeleteThe bumps are larger at the end is what i meant.
DeleteIs the shell very concave? Is it longer than it is wide? Are the bumps regularly spaced or somewhat random looking?
DeleteYes it's wider than long. There are rows near the edge but the rest of the shell has scattered bumps. If by concave you mean bent down then yes. The underside is not exposed but there were fragments of other shells similar that had bumps on the underside. I hope this helps!
ReplyDeleteok, so i got around to measuring it. It's only about 1.5 inches long, and 1.5 inches wide. it's wrinkled on it's sides. There are fine raidal ribs going from the umbo down to the margin, some wider than others. There are some spines, but they're more notacible to the top. It's very concave, yes. There's a VERY small pedicle hole. I found it associated with goniatites and proetid trilobites only, no phacopids. There's even a possible Leptodus. Is it Pennsylvanian?
ReplyDelete