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GordonC

 

Mahantango Formation Sparrowbush NY; Is there enough detail to ID? Looks somewhat like Dalmanites boothi. @piranha  Thanks, Gordon

Size: it will fit under a dime.

5cb611d76718c_TriloSP1.jpg.38e097a8bb34abab6acd4f4df43fa922.jpg

 

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Fossildude19

Nice find, Gordon. 

Looks like a Greenops pygidium. Not sure on the species. 

 

Rotated and contrasted.

 

5cb611d76718c_TriloSP1.jpg.38e097a8bb34abab6acd4f4df43fa922.jpg

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Tidgy's Dad

Nice find! :)

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Al Tahan

I think the cephalon is part of what helps distinguish the species but @Fossildude19 is right about the genus. Probably a greenops sp.

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GordonC

D. boothi  was reassigned to Greenops. See Plate 51 Trilobites of NY. (revised)

These from the Hamilton Formation in Maryland GS Plates. 5cb61bec7fb04_Dboothi.jpg.088105e8b8eaec5e365690ff1a033fd6.jpg

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DevonianDigger

This is almost certainly Greenops boothi. I think it's the only Greenops described from the Mahantango. It is at the very least, the only one in Trilobites of New York described from the formation.

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piranha

According to Lieberman & Kloc 1997, three Mahantango asteropygine species are reported:

 

Bellacartwrightia phyllocaudata

Greenops boothi

Greenops grabaui

 

Lieberman, B.S., Kloc, G.J. 1997

Evolutionary and biogeographic patterns in the Asteropyginae (Trilobita, Devonian) Delo, 1935.

American Museum of Natural History Bulletin, 232:1-127  PDF LINK

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Jeffrey P

Given that this fossil was collected on the New York side of the Delaware River would make it probably Mount Marion Formation, Marcellus Shale, Hamilton Group which is equivalent to the Mahantango Formation on the opposite side of the river. I agree that it is a Greenops pygidium. Given the current uncertainty regarding Greenops  species differentiations I simply label mine as Greenops sp. This, by the way, is the first specimen of Greenops I've seen east of Madison County. Shoot me if any of you have found one with me and I'm just forgetting.

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GordonC

Hi Jeff, I beg to disagree. Pa Geology Survey has mapped the Mahantango to the Delaware river within one mile of the location of collection.  NY has done nothing in this area. Political boundaries do not a formation make. Highest regards. G

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DevonianDigger
8 hours ago, piranha said:

According to Lieberman & Kloc 1997, three Mahantango asteropygine species are reported:

 

Bellacartwrightia phyllocaudata

Greenops boothi

Greenops grabaui

 

Lieberman, B.S., Kloc, G.J. 1997

Evolutionary and biogeographic patterns in the Asteropyginae (Trilobita, Devonian) Delo, 1935.

American Museum of Natural History Bulletin, 232:1-127  PDF LINK

4

 

And then there was Scott, lol!

 

I didn't have a chance to check that particular paper, I figured that Trilobites of NY was going to be enough for this one. My mistake! The pygidial spines do appear to be far too long for G. grabaui, and the proportion of the median pygidial spine seems too narrow for G. boothi. From the few details that are visible in the photos, it looks like the terminal ridge of the axial lobe is rather narrow. That, combined with the pygidial spines, actually leads me to think that B. phyllocaudata might be the best fit. Scott is way better at classification than I am, so I would really love to hear his feedback on this, but these are my two cents. Perhaps even @GerryK could give his thoughts.

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hemipristis

Paint me impressed that y'all can ID trilobite butts :P

 

 

trilobutts?

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