Eldredgeops vs. Viaphacops

[ScottBlooded]

So I’ve been digging in the Needmore formation for a few years now and, as an amateur, am always finding out that I call things the wrong name. I’m always trying to correct this but darned if you paleontologists don’t switch up the names all the time, I suspect to trip me up personally (joke).

The most abundant trilobite I find out there is what I was originally calling Phacops rana, because that’s what the first searches on the area were telling me. On this site, it was pointed out to me very early on that this was outdated info and that the new designation was Eldredgeops rana. All good, this was the last on that for a long time until I posted a photo to social media I identified as an Eldredgeops and had none other than THE Niles Eldredge comment telling me that this formation would be too early for Eldredgeops and what I’ve got on my hands are, in fact, Viaphacops.

As the bug has his name on it I’m inclined to believe him but now I’m torn because I’ve now seen a lot of other professionals, both here and other places, refer to Eldredgeops as being found in the Needmore.

This is of course a really pedantic triviality for an amateur like myself but there’s something wrong with my brain and I just need a definitive answer, then you guys aren’t allowed to change the name ever again. I see the dudes too often to not know what to call them.

Thanks as always!

 

[Thomas1982]

I agree with the great Niles Eldredge.  Needmore = Viaphacops.  

[oilshale]

Nomenclature is a matter of opinion, so it depends on individuals and may change over time. If one could analyze the genetic material of fossils, it would be easier to determine relationships.
 

[piranha]

In eastern North America Viaphacops has been described from various lower and Middle Devonian (Eifelian) formations. According to Burns 1991, at least one locality of the Needmore Fm. in Pendleton County, West Virginia does have Eldredgeops and Viaphacops occurring within the same layer. Eldredge 1973 has an extensive chapter describing the overall systematic paleontology and broad concept of numerous Viaphacops 'subspecies' entitled: "The Phacops cristata Complex". Thoracic axial nodes or spines are the key diagnostic feature for Viaphacops in the Needmore Fm.

 

Burns, J. 1991. Fossil Collecting in the Mid-Atlantic States with Localities, Collecting Tips, and

Illustrations of more than 450 Fossil Specimens. The Johns Hopkins University Press, 200 pp.

 

Eldredge, N. 1972
Systematics and Evolution of Phacops rana (Green, 1832) and Phacops iowensis Delo, 1935 (Trilobita) from the Middle Devonian of North America.
American Museum of Natural History Bulletin, 147(2):46-113  PDF LINK

 

Eldredge, N. 1973
Systematics of Lower and Lower Middle Devonian Species of the Trilobite Phacops Emmrich in North America.
American Museum of Natural History Bulletin, 151(4):286-337 PDF LINK
 

Iwasaki, Y. 2010
Systematics on Viaphacops Maximova, 1972 from Bolivia and Paleobiogeography of the Subfamily Phacopinae Hawle & Corda,
1847 for the Lower and Middle Devonian, With a Particular Emphasis on the Genus Paciphacops Maximova, 1972.

PhD Thesis, City University of New York, 213 pp.

 

Lespérance, P.J. 1991
Vincular Furrows in some Early Silurian and Devonian Phacopidae (Trilobita), Predominantly from North America.

Journal of Paleontology, 65(2):276-294

 

Stumm, E.C. 1954
Lower Middle Devonian Phacopid Trilobites from Michigan, Southwestern Ontario, and the Ohio Valley.
Contributions from the Museum of Paleontology, University of Michigan, 11(11):201-221  PDF LINK

 

 

chart from: Iwasaki 2010 – figures from: Eldredge 1973

[erose]

Why I label in pencil (or in a database).  Genus names are always getting updated, but species way less often. Phocops rana is the same as Eldregeops rana or whatever the current genus is. Same critter. Don't get too hung up on finding the most current. Index Fossils of North America was published 80 odd years ago and is still a great source of identifications.  But probably half the genera are old names.   Getting into hunting down the latest paper on a fossil is a whole 'nother game.

[Andúril Flame of the West]

I must agree that this new information throws everything a bit off-kilter. I've also made a few forays into the Needmore Shale, and, as you have, I've considered most Eldredgeops-type specimens to belong to the species Eldredgeops rana. I also feel compelled to agree with Eldredge's statement considering his expertise, but I have certainly seen numerous references to Eldredgeops rana occurring in the Needmore Shale. As @piranha mentioned, Jasper Burns does document the occurrence of Eldredgeops rana and Viaphacops at the same locality, though Burns certainly does not have the same authority as a researcher on par with Eldredge. So I suppose that the question still remains...

[cck]

On 10/5/2023 at 12:13 PM, piranha said:

Thoracic axial nodes or spines are the key diagnostic feature for Viaphacops in the Needmore Fm.

I agree… and both occur in the Needmore at some localities 

[piranha]

13 hours ago, Andúril Flame of the West said:

I must agree that this new information throws everything a bit off-kilter. I've also made a few forays into the Needmore Shale, and, as you have, I've considered most Eldredgeops-type specimens to belong to the species Eldredgeops rana. I also feel compelled to agree with Eldredge's statement considering his expertise, but I have certainly seen numerous references to Eldredgeops rana occurring in the Needmore Shale. As @piranha mentioned, Jasper Burns does document the occurrence of Eldredgeops rana and Viaphacops at the same locality, though Burns certainly does not have the same authority as a researcher on par with Eldredge. So I suppose that the question still remains...

 

 

The information from Burns 1991 is well established and substantiated:

 

 

Holloway, D.J., Scott, B.M. 2023 [prev. 2022]
Needmorella, A New Trilobite Genus of the Synphoriinae (Dalmanitidae) from the Lower–Middle Devonian of West Virginia.

Journal of Paleontology, 97(2):355-365

 

 

 

Woodward, H.P. 1943
Devonian System of West Virginia.
West Virginia Geological Survey Report, 15:1-655