Phacopid

[Kane]

Doing a little diagnostic work to better determine this phacopid species. In recent trips to one of my collecting sites, which typically is composed of imported Bois Blanc Fm fill (and just recently evidence of some Amherstberg Fm mixed in), I have had to reassess some of the specimens I've been pulling from there - and that includes several examples of what I wrote off as simply Eldredgeops rana. Consulting both Stumm (1954) and Ludvigsen (1979), E. rana is not reported in either of those formations. I've also paid particular attention to the comparative table in Whitely, Kloc and Brett's Trilobites of New York.

 

I'm including here my most "clean" specimen for closer analysis. First up is a comparison of the eye between a typical E. rana and the phacopid from my nearby pit. 

And now a closeup of the glabellar pustules. First up is E. rana, and the second is the unspecified one from the pit. Of note here is the regularity of the pustules on the E. rana while the specimen below are somewhat irregular in size and distribution.

[Kane]

And finally the "mystery specimen" itself. Note that the genal spine is somewhat blunt like E. rana, but seems a bit longer. Ludvigsen describes Phacops cristata in the Bois Blanc, while Stumm describes Phacops pipa. Stumm's description is as follows:

 

Glabella as in P. cristata, but with ornamentation somewhat more scattered and usually visible on casts. Third lobes obsolete; nuchal and third lateral furrows coalesced mesally. Nuchal lobe elevated, with a row of low tubercles. Eyes rather short, not attaining glabellar level, fewer than 45 facets, set well forward, leaving a considerable space between them and the postmarginal furrow. Genal spines short, rather blunt. Posterior cephalic margin rather straight.Thororachis nonspinose; otherwise as in P. cristata. (213). 

 

Hm. The eyes do seem to go beyond the glabellar level (I assume that to mean in terms of height), so not P. pipa? The plates I have on hand are not much help, either.  Also don't see a spine on the axial lobe to declare it P. cristata - but maybe it used to be there but was broken off? Urgh.

 

I can probably rule out P. canadensis (described as Viaphacops canadensis in Whitely, Kloc and Brett) due to the number of facets. I might not, however, entirely rule out that this is an E. rana as this hill & pit has provided some surprises before in terms of formations jumbling of the imported fill, yet the sparse material from the Hamilton Gp that has been trucked in has been dumped much later at a significant remove from the hill and pit where this specimen was acquired.

 

Any help from the experts is much appreciated!

[Fossildude19]

@GerryK   @piranha

[doushantuo]

genal spine size and shape might change with ontogeny,perhaps

[Kane]

Just now, doushantuo said:

genal spine size and shape might change with ontogeny,perhaps

I've considered that as well. The morphology can differ due to some genetic variations, aberrations, but I'm unsure what the limit case is between a natural deviation of a particular specimen within a species, and it actually being a different species. It would not have raised much of a flag for me if it was not on account of the location in which it was found. 

[doushantuo]

Trilobites have long been regarded as the hallmark of paleontology and New York as one of their Camelots.
Whiteley et al. have made the best of this happy coincidence,creating a well-written and profusely illustrated account
of the lives of New York trilobites. The book is organized into four main sections: the biology of trilobites,
their taphonomy, the systematic paleontology of New York trilobites, and a detailed overview of the regional
geology. A suite of 175 black-and-white plates of exquisitely photographed specimens follows. To be sure, this
book tells the tale of the trilobite; nonetheless, the authors have avoided the trap of being so engrossed with the fossils
themselves that the reader is allowed to look no further than the specimens. Instead, Whiteley et al. have made
great efforts to animate the organisms, highlighting their life habits as well as reconstructing the environments in
which they lived. The reader feels much more like he or she has been taken on a trilobite safari rather than observing
a caged animal in the zoo (or, in this case, an isolated specimen in a museum drawer). Unfortunately,there are a few disappointments in the book, such as the 
rather unsatisfactory explanations of evolutionary theory and cladistics on pages 30–31 (e.g., sympatric speciation
is dismissed, the concept of exaptation—that nonadaptive traits may be acquired and retained—is ignored, mutation
rates are stated to be constant and unchanging, and monophyly is defined simply as descent from a common ancestor).
This, plus the lack of scale in at least 25 of the plates and the limited number of citations in the regional
geology section (especially when referring to age determinations and previous tectonic and environmental interpretations),
are the most obvious drawbacks. Nonetheless,these amount to relatively minor distractions in the end and do not greatly detract from the book’s general
appeal and usefulness. Overall, I found this book to be an enjoyable, entertaining, and educational read and would
recommend it to anyone—amateurs, students, and professionals alike—with an interest in trilobites and/or the
bedrock geology of New York.
L I S A CHURCHILL-DICKSON

You quote from it so much...and it's nowhere to be found as a pdf..Believe me,I looked

[westcoast]

17 minutes ago, Kane said:

I've considered that as well. The morphology can differ due to some genetic variations, aberrations, but I'm unsure what the limit case is between a natural deviation of a particular specimen within a species, and it actually being a different species. It would not have raised much of a flag for me if it was not on account of the location in which it was found. 

Ha that is one big question there at the core of paleontology that is often ignored or avoided due to sample size or differing preservation. Has glabellar ornamentation been used to describe other phacopid species?....Ultimately go back to type specimens and compare and make your determination. With your attention to detail your observations are probably just as valid as whoever described them originally.

[doushantuo]

Are you kidding?

OF COURSE Kane has found a new species!!!

Sample size ,schnample size, my tiney hiney!!

******** "Allometric" doushantuo,reporting live from the Forum,watching things unfold as they happen***********

 

[Kane]

1 minute ago, doushantuo said:

Are you kidding?

OF COURSE Kane has found a new species!!!

Sample size ,schnample size, my tiney hiney!!

Ha! Somehow I very much doubt that. Phacopids have been among the most studied of trilobites that the probability of me stumbling across an undiscovered/unidentified species is about as good as winning the lottery or creating something new to say about Aristotle  

[doushantuo]

That was "informative"? 

Perhaps i should use Fe-y a lot less

knellforteyrsbl20050304.pdf

[westcoast]

Using the word 'allometric' in the same paragraph as the word 'hiney'- I didn't know that was possible until now. I applaud you sir.

[doushantuo]

meanwhile:

From the same Spr**ger rag:

 

 

 

[piranha]

The taxonomy on these is tangled.  P. cristata is now Viaphacops cristata and P. pipa is Viaphacops pipa.  Your specimen appears to be Eldredgeops rana.

[Kane]

Thanks for the taxonomic clarification and ID, Scott. 

 

And that confirms a new headache: the fill in this area contains at least three different formations all tossed in willy-nilly from multiple locations. I've pulled a good many specimens from this site, so I'd be loath to leave it, so it means I'll have to rely much more on diagnostic details as I will not be able to rely so confidently on the assumed formation of origin. 

 

Perhaps I'll just rename it the Hodge-Podge Group, with its members, Sampler, Random, and Flea Market. 

[GerryK]

Your trilobite tentatively looks like an Eldredgeops but I need more information from you to confirm this identification. If you could do the following.

1) count the number of files in the eye, that is the number of vertical lenses in the eye.

2) remove more matrix from the lateral border of the cephalon and take another picture to determine if it is marginated

3) remove more matrix from the top of the cephalon and take a straight down picture so I can  see the placement of the furrows.

 

If you can do this and post the pictures, I can give a better determination as to what you have.

[Kane]

14 hours ago, GerryK said:

Your trilobite tentatively looks like an Eldredgeops but I need more information from you to confirm this identification. If you could do the following.

1) count the number of files in the eye, that is the number of vertical lenses in the eye.

2) remove more matrix from the lateral border of the cephalon and take another picture to determine if it is marginated

3) remove more matrix from the top of the cephalon and take a straight down picture so I can  see the placement of the furrows.

 

If you can do this and post the pictures, I can give a better determination as to what you have.

Thanks, Gerry.

 

When you say vertical lenses, the individual lenses separated by the sclera do not neatly match up on a vertical axis at times, despite the overall "honeycomb" arrangement. I'll try to do a count as none of my cameras seem equipped to provide a clear closeup image, and the digital scope would require some kind of stacking software I haven't been able to find for my Mac. For now, I did remove some of the tough matrix (with a Dremel - best I got ), and can provide a few preliminary pictures. As you can see, it is little more than half a specimen (the other side was lost to erosion). I'm not seeing any margination on the cephalon.

[Kane]

It's tricky to do a count with a loupe, so I hope this is fairly accurate. The vertical lens count is 1, 2, 2, 3, 3, 4, 4, 4, 4, 4,4 ,4 5, 5, 5. I've quickly put together the arrangement in Paintbrush.

[Malcolmt]

If you bring it with you when we meet up, I'll clean it up for you. I think you mentioned you might have a few other nice ones  that you wanted to bring with you. The group on Saturday has dwindled in number due to the passing of JIm Cox and his funeral on Friday. Roger from Germany and a few from the Dry Dredgers will be there on Sunday.

[Kane]

15 minutes ago, Malcolmt said:

If you bring it with you when we meet up, I'll clean it up for you. I think you mentioned you might have a few other nice ones  that you wanted to bring with you. The group on Saturday has dwindled in number due to the passing of JIm Cox and his funeral on Friday. Roger from Germany and a few from the Dry Dredgers will be there on Sunday.

Thanks, Malcolm - much appreciated, and I look forward to the visit. I will be there on the Saturday afternoon as well as all day Sunday. 

[Fossil-Hound]

Very informative.