Shift in Paradigm

History has a strong role in paleontology — and not just in the geologic sense. We are commonly bound to previous works in both nomenclature and models and some of these can be incredibly frustrating to deal with. I have in the past discuss the frustration of dealing with poorly described taxa or taxa described on poorly preserved specimens especially, but not limited to, Charles Elmer Resser (e.g., Sundberg, 2007). Christina Lochman-Balk, Franco Rasetti, Allison (Pete) Palmer, Richard (Dick) Robison, and many others have tried to make sense of this taxonomic mess.

It is time to try something different. In a recent paper, Mark Webster and I (Sundberg and Webster, in press) have proposed to just drop the old taxonomic names that are based on poorly described/illustrated/preserved specimens (e.g.,
Eoptychoparia) and define new genera/species based on several specimens that represent different parts of the exoskeleton (not just the cranidium) and preferably articulated specimens at different growth stages. Oh yes, this definitely runs the risk of having our new genera/species synonymized with older named taxa; but these historically older taxa cannot be fully characterized at present and until someone goes out and collect topotype specimens, it is unlikely that they will be characterized soon.

It is just names, why should we care? These older names carry a lot of baggage making it difficult to determine the phylogeny of these (mainly early to middle Cambrian) trilobites. One study (Sundberg, 2004) illustrates that species defined on cranidia of these poorly defined taxa (
Onchocephalus) are unstable in their position in a cladogram where as taxa known from more complete specimens or have unique cranidial morphology are much more stable within the cladogram.


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Reconstruction of the type species of a new genus and species of “ptychoparioid” trilobites from the Harkless Formation, Nevada (mid Dyeran).


Sundberg, F.A., 2004, Cladistic analysis of the EarlyMiddle Cambrian kochaspid trilobites (Ptychopariida): Journal of Paleontology, v. 78, p. 920–940.

Sundberg, F.A., 2007, Nightmare on Resser Street, in Landing, E., Milukic, D.G., and Kluessendorf, J., eds., Fabulous Fossils—300 Years of Worldwide Research on Trilobites: New York State Museum Bulletin 507, p. 213–224.

Sundberg, F.A., and Webster, M., in press, “Ptychoparioid” trilobites of the Harkless Formation and Mule Spring Limestone (Cambrian Series 2, Stage 4), Clayton Ridge, Nevada: Journal of Paleontology.

Fred Sundberg
Show Low, Arizona
sundbergfred@gmail.com

Links

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The Trilobite Papers 20 are part of the PaleoNet system. Sponsorship of The Palaeontological Association is gratefully acknowledged.