Devonian Escargot In Central Ny

[Jeffrey P]

On Monday I visited a site north of Morrisville, Madison County, NY. It is a roadcut exposure of the Marcellus Shale, the lowest part of the Hamilton Group. The bottom part is an exposure of the Bridgewater Member and the top is the Oatkacreek Formation. It was my third time there and each visit has presented a different experience: In the spring of 2013 my companion and I explored the talus slopes that cover most of the exposure and found a number of specimens of the top-shaped gastropod, Bembexia subcomarginata along with brachiopods and bivalves. I returned in the spring of 2014, this time exploring the shale outcrops above the talus slope and picked a number of Bembexia right from the shale wall. On Monday I climbed the steep talus slope again and dug into the shale exposure at the top and discovered a thin bed that was rich in well preserved examples of the tiny corkscrew-shaped gastropod, Paleozygopleura. Also found a number of Bembexia, plus bivalves and brachiopods including Grammysia bisculata and Spinocyrtia granulosa, and one pretty large bivalve with both valves preserved that I first thought was a concretion, and the smooth-shelled nautiloid, Michelinoceras..

This is a photo of the road cut with my vehicle in the foreground for scale.

[Jeffrey P]

^{This is a photo of my dig site at near the top of the exposure}

^.

[Jeffrey P]

This is a photo of my Bembexia finds.

[Jeffrey P]

These are the Paleozygopleura. Never found so many in one day.

[Jeffrey P]

And this is a photo of all my finds:

[izak_]

They are really nice finds - great job! Especially those spiral gastropods....

Izak

[Ludwigia]

Well done!

[Jeffrey P]

Thanks Izak and Roger. The talus slope was quite steep and loose, making this one of the more challenging sites I've been to in terms of access. Fortunately, the shale itself is relatively soft and fractures easily and more often than not the fossils (usually preserved in black calcite) pop out complete. I tried digging in another spot but couldn't get good footing.

[ZiggieCie]

THX for taking us along in your pocket. Great finds and a successful day.

[Pagurus]

Too bad there wasn't any Devonian butter to go with the snails. Looks like you had a rewarding day, Jeffery. Thanks for sharing it. Love those Paleozygopleura but the Bembexia would be more filling.

[Fossildude19]

Jeff,

Good report and finds,... congratulations!

Looks like you did well.

Interesting you found that thin bed of Paleozygopleura.

Did you happen to find any other fossils in that bed?

Just wondering if the Bembexia were in the same area at the same time.

Thanks for posting this - Looks like a place I'd like to visit sometime.

Kind regards,

[Jeffrey P]

Thanks Mike, Ziggie, and Tim. The Paleozygopleura were restricted to only the one thin layer. Didn't find any in any other places. There were other fossil shells in that same layer. Just above it were more bivalves and just below it is where I found the nautiloids pieces. Bembexia seemed to be present in a number of beds. Higher up there was a bed where only Amboceila brachiopods were found and much higher where I started digging, mostly imprints of Mucrospirifers. I was specifically looking for a bed(s) where the fossil shells had been replaced by calcite.

[njfossilhunter]

Very cool finds Jeff....Like what Tim said...That maybe a site I would like to visit. Those Gastropods are looking really sweet.

Tony

[Ridgehiker]

Thanks for sharing

It's always a plus to see Gastropods and bivalves from the Paleozoic....interesting how both are almost entirely absent from many excellent collecting sites....lots of brachiopods, blastoids , corals, bryozoa but often few if any molluscs. So different from today's sites where a brachiopod can be a gem found among the molluscs.

[Wrangellian]

Yes, here in our Cretaceous rocks the brachs are rare and snails/bivalves common. But the shale itself looks exactly the same as at my site! Funny to think they are so different in age but the same lithology and much the same preservation, so presumably gives you an idea of how much faunal change has occurred over that time in this type of habitat.

Nice to see some exposure photos to go along with the fossils.

[Jeffrey P]

Brachiopods were certainly dominant in the Devonian, but in Central NY, probably because of its proximity to the Catskill Delta to the east, bivalves and gastropods are abundant too and take many interesting forms. Love to check out your Cretaceous shale sometime. Maybe next time I'm in the neighborhood.

[GerryK]

On Monday I visited a site north of Morrisville, Madison County, NY. It is a roadcut exposure of the Marcellus Shale, the lowest part of the Hamilton Group. The bottom part is an exposure of the Bridgewater Member and the top is the Oatkacreek Formation. It was my third time there and each visit has presented a different experience: In the spring of 2013 my companion and I explored the talus slopes that cover most of the exposure and found a number of specimens of the top-shaped gastropod, Bembexia subcomarginata along with brachiopods and bivalves. I returned in the spring of 2014, this time exploring the shale outcrops above the talus slope and picked a number of Bembexia right from the shale wall. On Monday I climbed the steep talus slope again and dug into the shale exposure at the top and discovered a thin bed that was rich in well preserved examples of the tiny corkscrew-shaped gastropod, Paleozygopleura. Also found a number of Bembexia, plus bivalves and brachiopods including Grammysia bisculata and Spinocyrtia granulosa, and one pretty large bivalve with both valves preserved that I first thought was a concretion, and the smooth-shelled nautiloid, Michelinoceras..

This is a photo of the road cut with my vehicle in the foreground for scale.

IMG_2963.JPG

Jeff

I am very familiar with this locality, collected the site many times. However, I want to correct you on the stratigraphy of the locality. Dr. Gordan Baird and Dr. Carl Brett have studied the stratigraphy of the area and have determined that the lower shale beds are the Peckport Member and the top bed is the Mottville Member, both of the Marcellus Formation. The older literature referred to the lower beds as the Solsville or Bridewater Member which are in fact below the exposure you collected at.

Gerry

[Jeffrey P]

Jeff

I am very familiar with this locality, collected the site many times. However, I want to correct you on the stratigraphy of the locality. Dr. Gordan Baird and Dr. Carl Brett have studied the stratigraphy of the area and have determined that the lower shale beds are the Peckport Member and the top bed is the Mottville Member, both of the Marcellus Formation. The older literature referred to the lower beds as the Solsville or Bridewater Member which are in fact below the exposure you collected at.

Gerry

Thanks Gerry, but I was told by a local stratigraphy professor that upper formation is the Oatkacreek. So, it appears there's some controversy about their assignment. I've been exposed to many such controversies regarding the stratigraphic assignment of fossil sites. If you have any other information about the stratigraphy of this site, I welcome you to post it. I do appreciate the feedback and I'll leave it up to the readers to do their own research and come to their own conclusions. Curious what type of fauna you've been able to extract from this locality.

[erose]

Thanks Gerry, but I was told by a local stratigraphy professor that upper formation is the Oatkacreek. So, it appears there's some controversy about their assignment. I've been exposed to many such controversies regarding the stratigraphic assignment of fossil sites. If you have any other information about the stratigraphy of this site, I welcome you to post it. I do appreciate the feedback and I'll leave it up to the readers to do their own research and come to their own conclusions. Curious what type of fauna you've been able to extract from this locality.

This is a great example of why it is so important to have a good description of the site and strata you collected it from in your notes and catalog. Formation names change, get modified or re-evaluated but if your notes are good that doesn't matter in the long run.

This also why I keep "reference" notes in my location catalog. I note what paper, map or personal communication I derived the geology from and can then go back and take a second look as needed.

When I lived in New York and wrote field trip guides for the NYPS I often found myself having to track down the "latest" understanding of a particular site. Also rock units get bumped up and down in formal status. What was once just a member becomes a formation and vica versa. Not sure how well this rule is followed but generally a formally recognized unit is capitalized and informal units are not. Example would be the Ludlow Formation compared to the blah blah hill member.

[GerryK]

Thanks Gerry, but I was told by a local stratigraphy professor that upper formation is the Oatkacreek. So, it appears there's some controversy about their assignment. I've been exposed to many such controversies regarding the stratigraphic assignment of fossil sites. If you have any other information about the stratigraphy of this site, I welcome you to post it. I do appreciate the feedback and I'll leave it up to the readers to do their own research and come to their own conclusions. Curious what type of fauna you've been able to extract from this locality.

Jeff

As I stated before, Dr. Gordon Baird and Dr. Carl Brett have studied the stratigraphy of the Marcellus Formation and determined the locality you collected to be the Pecksport and Mottville Members. I have contacted Dr. Baird about the locality and he emailed me a lot of references on the revision of the Marcellus Formation. These are the references, Ver Straeten, Griffing & Brett 1994; Baird, Brett & Ver Straeten 1999 and Baird, Brett & Ver Straeten 2000, all in the NYSGA Field Guides. You are correct in indicating that the locality is Oatka Creek Formation. What the authors did is raise the Marcellus Formation to the Marcellus Subgroup and dividing the Subgroup into the lower Union Springs Formation and the upper Oatka Creek Formation and the locality has the Pecksport and the Mottville Members exposed. The problem I am having is trying to find a published report revising the stratigraphy of the locality. I'm still trying to find a reference and if I find one I'll let you know.

You asked what type of fauna I've been able to extract from this locality. This Pecksport locality has been very important to me, yielding some of the oldest Hamilton fossils in New York. I have 3 examples below.

1) From the Pecksport I have collected the oldest specimens of the brachiopod Spinocyrtia. So far I have not found any Spinocyrtia from lower units. These specimens of Spinocyrtia may be a new species. The specimens I collected were give to Dr. Day who will be studying these specimens and many other specimens of the Spinocyrtiidae and will be working on a revision of this group.

2) The specimens of the trilobite Eldredgeops that I've collected from this locality are fascinating. So far they are the oldest specimens of Eldredgeops known to me to occur in New York.

The typical Eldredgeops rana from Hamilton of New York has eyes with 17 files and a maximum of 6 lenses in a file. Eldredgeops milleri is an older trilobite occurring in the Marcellus equivalents of the Arkona Shale of Ontario, Canada and the Silica Shale of Ohio. It has 18 files with a maximum of 8 lenses in small specimens and can get 9 lenses in large specimens. Some Eldredgeops from the Pecksport have both eyes of 17 files, while other specimens will have one eye with 17 and the other with 18 files and all eyes with have a maximum of 7 lenses in a file. These Eldredgeops will not fit into either species of E. rana or E.milleri but seem to be some sort of "transitional form." I have been searching for older specimens of Eldredgeops with no luck hoping to find an Eldredgeops milleri, which would be nice to have an E. milleri, the Pecksport "transition form" and E. rana from New York.

3) Again, the Asteropyginae are the oldest I know of in the Pecksport. These trilobites are rare to find and I have no idea if they are some sort of Greenops, Stummiana, Bellacartwrightia or something else.

I conclude that this locality has yielded some fascinating fossils and I have no idea how many other hidden treasures may still be there.

[Jeffrey P]

Jeff

As I stated before, Dr. Gordon Baird and Dr. Carl Brett have studied the stratigraphy of the Marcellus Formation and determined the locality you collected to be the Pecksport and Mottville Members. I have contacted Dr. Baird about the locality and he emailed me a lot of references on the revision of the Marcellus Formation. These are the references, Ver Straeten, Griffing & Brett 1994; Baird, Brett & Ver Straeten 1999 and Baird, Brett & Ver Straeten 2000, all in the NYSGA Field Guides. You are correct in indicating that the locality is Oatka Creek Formation. What the authors did is raise the Marcellus Formation to the Marcellus Subgroup and dividing the Subgroup into the lower Union Springs Formation and the upper Oatka Creek Formation and the locality has the Pecksport and the Mottville Members exposed. The problem I am having is trying to find a published report revising the stratigraphy of the locality. I'm still trying to find a reference and if I find one I'll let you know.

You asked what type of fauna I've been able to extract from this locality. This Pecksport locality has been very important to me, yielding some of the oldest Hamilton fossils in New York. I have 3 examples below.

1) From the Pecksport I have collected the oldest specimens of the brachiopod Spinocyrtia. So far I have not found any Spinocyrtia from lower units. These specimens of Spinocyrtia may be a new species. The specimens I collected were give to Dr. Day who will be studying these specimens and many other specimens of the Spinocyrtiidae and will be working on a revision of this group.

2) The specimens of the trilobite Eldredgeops that I've collected from this locality are fascinating. So far they are the oldest specimens of Eldredgeops known to me to occur in New York.

The typical Eldredgeops rana from Hamilton of New York has eyes with 17 files and a maximum of 6 lenses in a file. Eldredgeops milleri is an older trilobite occurring in the Marcellus equivalents of the Arkona Shale of Ontario, Canada and the Silica Shale of Ohio. It has 18 files with a maximum of 8 lenses in small specimens and can get 9 lenses in large specimens. Some Eldredgeops from the Pecksport have both eyes of 17 files, while other specimens will have one eye with 17 and the other with 18 files and all eyes with have a maximum of 7 lenses in a file. These Eldredgeops will not fit into either species of E. rana or E.milleri but seem to be some sort of "transitional form." I have been searching for older specimens of Eldredgeops with no luck hoping to find an Eldredgeops milleri, which would be nice to have an E. milleri, the Pecksport "transition form" and E. rana from New York.

3) Again, the Asteropyginae are the oldest I know of in the Pecksport. These trilobites are rare to find and I have no idea if they are some sort of Greenops, Stummiana, Bellacartwrightia or something else.

I conclude that this locality has yielded some fascinating fossils and I have no idea how many other hidden treasures may still be there.

Thanks for your fascinating information which contributes a lot to this thread. I would also direct readers to a bulletin published in 1983 by the AMNH Vol. 174, article #3 by J. Bowman Bailey; Middle Devonian Bivalvia from the Solsville Member(Marcellus Formation) Central New York State. Though the stratigraphic information is outdated, the information about the bivalves themselves and pictures are quite excellent and should be useful for anyone interested in Devonian bivalves.Again, thanks. Next time I go I'll keep an eye out for those trilobites.