trilobite help

[jpc]

Hi all... 

One of our students found this in Cambrian Gros Ventre Fm of Wyoming.  Wyoming trilobites are pretty rare.  I plan to make this the Fossil Of The Month for out Tate Museum newsletter but I need help IDing it.  All of you who help me ID it will get credit in the Newlsetter.  It is about 2cm long.

 

I know there are some trilofolks on here who can convince me it is a so-and-so.  

 

Thanks, y'all.

 

 

[ynot]

@piranha I think this is right up Your ally!

[FossilDAWG]

I'd say it's a ptychoparid.  Beyond that, "Hmmmm" .  Maybe I can hit the books when I get home, but no doubt piranha will have solved it by then.

 

Don

[Fossildude19]

 

Here is a list of fauna, including Trilobites, that are present in the Cambrian Gros Ventre Fm.

[FossilDudeCO]

nice find JP!!

that is sweet a little fella!

[piranha]

Two similar possibilities are Ehmania and Modocia.  The attached examples are not from Wyoming, but shown for comparison of similar features.

I sent the photo to friend who is a leading specialist on Wyoming trilobites.  Hopefully he will recognize the species.  I will post the update shortly.

 

 

[fifbrindacier]

Nice

[piranha]

Based on the deep pleural furrows, my colleague agrees it matches best with: Ehmania sp.

 

 

 

 

[Fossildude19]

Thanks for the follow up on this, Scott.  

[jpc]

Thanks you guys.  I noticed the info from the paleobiology database is based on Sepkokski, unpublished data.  Darn.  Sepkokski died a few years back.  It would have been nice to ask him...

[RJB]

This is a new one.  Never knew that Wyoming had any trilobites at all?  Nice find.

 

RB

[piranha]

13 hours ago, jpc said:

Thanks you guys.  I noticed the info from the paleobiology database is based on Sepkokski, unpublished data.  Darn.  Sepkokski died a few years back.  It would have been nice to ask him...

 

 

Fortunately there are quite a few publications with Cambrian trilobites from Wyoming.  

Please let me know if you want anything from this list and I will be happy to send them.

 

 

Beebee, R.A. & Rónadh, Cox (1998)
Dynamics of Marine Transgression onto a Non-Linear Shoreline: The Middle Cambrian Flathead Sandstone, Clarks Fork Valley, Wyoming.

The Mountain Geologist 35(3):91-101

 

Cygan, Norbert E. & Koucky, Frank L. (1963)
The Cambrian and Ordovician rocks of the east flank of the Big Horn Mountains, Wyoming.
Wyoming Geological Association 1963:26-37

 
Deland, Charles R. & Shaw, Alan B. (1956)
Upper Cambrian Trilobites from Western Wyoming.
Journal of Paleontology 30(3):542-546
 
DeLand, Charles R. (1954)
Cambrian stratigraphy and upper Cambrian trilobites of the southwestern flank of the Wind River Mountains, Wyoming.
M.A. Thesis, University of Wyoming, 135 pp.
 
Denson, Norman M. (1942)
Late middle Cambrian trilobite faunas and stratigraphy of Alberta, Montana, Wyoming and Utah.
Ph.D. Thesis, Princeton University, 195 pp.
 
Durkee, Edward F. (1953)
Cambrian Stratigraphy and Paleontology of the East Flank, Bighorn Mountains, Johnson and Sheridan Counties, Wyoming.
M.S. Thesis, University of Wyoming, 170 pp.
 
Grant, Richard E. (1958)
Cambrian faunas of the Snowy Range formation, southwestern Montana and northwestern Wyoming.
PhD Thesis, University of Texas, 553 pp.
 
Grant, Richard E. (1965)
Faunas and Stratigraphy of the Snowy Range Formation (Upper Cambrian) in Southwestern Montana and Northwestern Wyoming.
Geological Society of America Memoir, 96:1-171

 

Hose, Richard K. 1955.
Geology of the Crazy Woman Creek Area, Johnson County, Wyoming. 
United States Geological Survey Bulletin 1027-B

 

Lochman-Balk, Christina (1955)
Cambrian Stratigraphy of the South and West Margins of Green River Basin.
Wyoming Geological Association 1955:29-37

 

Lochman-Balk, Christina (1957)
Paleoecology of the Cambrian in Montana and Wyoming. 
Geological Society of America Memoir 67:117-162

 

Lochman-Balk, Christina (1960)
The Cambrian Section of Western Wyoming. 
Wyoming Geological Association 1960:98-108
 
Lochman-Balk, Christina & Hu, Chung-Hung (1960)
Upper Cambrian Faunas From the Northwest Wind River Mountains, Wyoming. Part I.
Journal of Paleontology, 34(5):793-834
 
Lochman-Balk, Christina & Hu, Chung-Hung 1961
Upper Cambrian Faunas From the Northwest Wind River Mountains, Wyoming. Part II.
Journal of Paleontology, 35(1):125-146
 
Lochman-Balk, Christina & Hu, Chung-Hung (1962)
Upper Cambrian Faunas From the Northwest Wind River Mountains, Wyoming, Part III.
Journal of Paleontology, 36(1):1-29

 

Love, John David (1939)
Geology along the Southern Margin of the Absaroka Range, Wyoming.
Geological Society of America, Special Paper 20:1-134

 

Middleton, Larry T.; Steidtmann, James R.; DeBour, Daniel A. (1980)
Stratigraphy and Depositional Setting of Some Middle and Upper Cambrian Rocks, Wyoming.
Wyoming Geological Association 1980:23-35

 

Miller, B. Maxwell (1936a)
Cambrian stratigraphy of northwestern Wyoming.

Journal of Geology 44(2):113-144

 

Miller, B. Maxwell (1936b)
Cambrian Trilobites from Northwestern Wyoming.

Journal of Paleontology 10(1):23-34
 
Saltzman, Matthew R. (1999)
Upper Cambrian carbonate platform evolution, Elvinia and Taenicephalus zones (Pterocephaliid-Ptychaspid biomere boundary), Northwestern Wyoming.
Journal of Sedimentary Research, 69(4):926-938
 
Schwimmer, David Richard (1973)
The Middle-Cambrian biostratigraphy of Montana and Wyoming.
Ph.D. Thesis, State University of New York at Stony Brook, 452 pp.
 
Schwimmer, David Richard (1975)
Quantitative taxonomy and biostratigraphy of Middle Cambrian trilobites from Montana and Wyoming.
Mathematical Geology, 7(2):149-166
 
Shaw, A.B. (1956a)
A Cambrian Aphelaspis Fauna from Steele Butte, Near Boulder, Wyoming.
Journal of Paleontology, 30(1):48-52
 
Shaw, A.B. (1956b)
Notes on Modocia and Middle Cambrian trilobites from Wyoming.
Journal of Paleontology, 30(1):141-145

 

Shaw, Alan B. (1957)
Cambrian of the southwestern Wind River basin, Wyoming.

Wyoming Geological Association 1957:9-16

 

Shaw, Alan B. & DeLand, C.R. (1955)
Cambrian of Southwestern Wyoming.

Wyoming Geological Association 1955:38-42

 

Thomas, Horace D. (1948)
Summary of Paleozoic Stratigraphy of the Wind River Basin, Wyoming.
Wyoming Geological Association 1948:79-95

 

Thomas, Horace D. (1951)
Summary of Paleozoic Stratigraphy of the Region About Rawlins, South-Central Wyoming.

Wyoming Geological Association 1951:32-36

 

Thomas, Robert C. (2008)
A field guide to the Cambrian section at Beartooth Butte, northwestern Wyoming.
Northwest Geology 37:159-172

 

Witkind, Irving J. (1969)
Geology of the Teepee Creek Quadrangle Montana-Wyoming. 
U.S. Geological Survey Professional Paper 609

 

[jpc]

Holy Cambrian, batman.  Being a mesozoic and tertiary guy, i had no idea.  Thanks for the info and offer.

[fifbrindacier]

On 25 mars 2017 at 4:02 AM, piranha said:

Based on the deep pleural furrows, my colleague agrees it matches best with: Ehmania sp.

Your colleague is a best expert than me, and i see the furrows more look like the furrows of the Ehmania. But i wonder : i see a difference of the part i circled between jpc's student's find with the Ehmania and a resemblance with the Modocia. But maybe should i change my glasses.

[piranha]

2 hours ago, fifbrindacier said:

Your colleague is a best expert than me, and i see the furrows more look like the furrows of the Ehmania. But i wonder : i see a difference of the part i circled between jpc's student's find with the Ehmania and a resemblance with the Modocia. But maybe should i change my glasses.

 

 

As I already mentioned; the examples shown above are only for comparison of similar features.  My initial suggestion of Ehmania or Modocia was purposely not specific, and my colleague agreed it was Ehmania sp., but was also reluctant to assign a species.  I agree the occipital ring does match better with Modocia, but it is also important to remember there is a lot of variability among the 20+ different species of Ehmania.  In any event, the examples attached above share more morphological similarities than differences.

 

[westcoast]

Yes I noticed the larger occipital ring too but it's also worth noting that there is a Richard E Grant and a David Schwimmer in the bibliography.

[piranha]

30 minutes ago, westcoast said:

Yes I noticed the larger occipital ring...

 

 

As I mentioned, there is a lot of variability among the 20+ different species of Ehmania.

Note the occipital ring of Ehmania weedi from the Treatise on Invertebrate Paleontology.

 

 

30 minutes ago, westcoast said:

...and a David Schwimmer in the bibliography.

 

 

Very good observation, the mystery specialist is revealed! 

 

[fifbrindacier]

Thanks Piranha.

[piranha]

Today I sent the photo to another colleague.  As luck would have it, another trilobite specialist (that jp mentioned to me) also sent him the photo.  

Small world, at least great minds think alike... lol 

 

At any rate, he suggested Ehmaniella cf. waptaensis as a possibility.

 

 

figure from:

 

Rasetti, Franco (1951)
Middle Cambrian stratigraphy and faunas of the Canadian Rocky Mountains.
Smithsonian Miscellaneous Collections, 116(5):1-277

 

[jpc]

small world indeed.  Thanks for helping out.  I am featuring this trilobite as the Fossil of the Month in the next Tate Museum Newsletter, and piranha is one of the folks I will be thanking in print.