Greenops from Hungry Hollow

[Monica]

Hello again!

 

I have one more ID request (for now ). 

 

I received this Greenops as a gift, but I think I deleted the email which stated the exact location/formation information - does anyone recognize the matrix that it's on?  And is it G. widderensis or is it G. arkonensis?  I have a document stating that these two species have been found at Hungry Hollow (near Arkona, Ontario, Canada; mid-Devonian in age) - are there two different Greenops species found at Hungry Hollow or only one (widderensis)?  Thanks so much!

 

Monica

 

I'll tag @Kane and @middevonian for this one 

 

[Kane]

G. widderensis.

[Monica]

Just now, Kane said:

G. widderensis.

 

Thanks, Kane!

 

Do you by any chance recognize the matrix?  The document you gave me a couple of years ago states that G. widderensis occurs in both the Hungry Hollow Formation and the Widder Formation - I'm just wondering if I can narrow it down to one of the two formations...

[Kane]

And this is classic Widder shale matrix as could be found on the high north and south banks. Just an FYI, the Hungry Hollow is now a member of the Widder Fm. 

[Monica]

1 minute ago, Kane said:

And this is classic Widder shale matrix as could be found on the high north and south banks. Just an FYI, the Hungry Hollow is now a member of the Widder Fm. 

 

Thanks once again, Kane!!! 

[Kane]

My pleasure. We spent a lot of summers excavating in the Widder. The Stumm and Wright articles are largely out of date now, so one hopes an updated faunal list will be forthcoming!

[FossilDAWG]

Greenops arkonensis is now placed in the genus Stummia.  Although both Stummia arkonensis and Greenops widderensis occur in the Widder, S. arkonensis is much rarer than G. widderensis.   Although I don't recall off the top of my head the features that distinguish the two species, your specimen seems to me to be identical to the common G. widderensis.  Note that I use "common" in a relative sense, as complete G. widderensis (even lacking an eye) are not all that common.

 

Don

[Kane]

29 minutes ago, FossilDAWG said:

Greenops arkonensis is now placed in the genus Stummia.  Although both Stummia arkonensis and Greenops widderensis occur in the Widder, S. arkonensis is much rarer than G. widderensis.   Although I don't recall off the top of my head the features that distinguish the two species, your specimen seems to me to be identical to the common G. widderensis.  Note that I use "common" in a relative sense, as complete G. widderensis (even lacking an eye) are not all that common.

 

Don

Stummiana arkonensis

 

Lieberman, B.S., & Kloc, G.J. (1997)

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

Bulletin of the American Museum of Natural History 232:1-127

LINK

 

Excerpt:

 

Characters suggesting exclusion of species assigned to Stummiana from the Greenops clade include: the condition of the anteriormost portion of the palpebrum, which is opposite the PMI in Stummiana but opposite a point between the medial part of L3 and the PMI in Greenops; the fixigena, which has a distinct bulge medially in Stummiana but is evenly sloping from the axial furrow to the palpebrum in Greenops. (p. 105).