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Sagebrush Steve

Need help with trilobite morphology

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Sagebrush Steve

I'm starting to sort through the trilobites I found at Oak Springs and need some help.  My degree is in electrical engineering, which means when I was in college I never had to take any of those pesky courses in biology, zoology, etc.  But that puts me at a disadvantage now as I read through the descriptions of the candidate trilobites and try to make sense of them.  There are a fair number of papers published on the trilobites of the Cambrian in California and Nevada.  To help identify what I have collected I'm using this one: Carrara Formation.  Here is where I am having difficulty.  The descriptions in this paper include features that don't appear on the diagrams I have of trilobite morphology.  I have compiled one example here: 

 

Gilberti.pdf

(reproduced as a low-res JPEG below). 

 

The color photo at the top is the specimen I'm trying to identify.  I think it might be an Olenellus gilberti, so I have pasted that description below the photo, along with three photos of O. gilberti  from the paper.  (Below those photos is a diagram of trilobite morphology I pulled from the Internet.)  The description of O. gilberti  includes at least two features that don't show up on the morphology diagram: occipital ring (is this the same as occipital lobe?) and intergenal spine (I don't think this is the same as genal spine?).  More concerning to me is this part of the description:

 

     "Glabella elongate, separated from frontal border by preglabellar area as wide or wider than anterior border."

 

In my novice opinion, the examples in photos 6-8 from the paper show glabellas that extend pretty much all the way to the anterior border.  In my specimen the preglabellar area is much wider, which would seem to be more consistent with the written description. 

 

Any help would be appreciated.  Of course I'd like to identify the specimen, but what I'd really like are pointers on how to interpret the morphology descriptions.  Maybe I've got an O. fowleri instead of O. gilberti, but if I don't understand how to interpret the descriptions I won't be successful in identifying it.  Is there a book I should lay my hands on?

 

Gilberti.thumb.jpg.c07c7e1d13889464f30a824bdb750d2a.jpg

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fossilcrazy

Hi Sagebrush Steve,

 

Perhaps this quick identifier can help visually ID your Oaks Springs finds. If things get tricky Pete Palmer has some good publications on Cambrian Trilobites from the SW states.

59d41d2563b13_OlenellusSp.thumb.jpg.2219182f42365083e0b3f0c2ece5283a.jpg 

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piranha
Whittington, H.B. (1989)
Olenelloid trilobites: Type species, functional morphology and higher classification.
Philosophical Transactions of the Royal Society of London, Series B, 324:111-147
 
Palmer, A.R., & Repina, L.N. (1993)
Through a glass darkly: Taxonomy, phylogeny, and biostratigraphy of the Olenellina.
University of Kansas Paleontological Contributions, New Series, 3:1-35    PDF LINK
 
Lieberman, B.S. (1998)
Cladistic analysis of the Early Cambrian olenelloid trilobites.
Journal of Paleontology, 72(1):59-78
 
Lieberman, B.S. (1999)
Systematic revision of the Olenelloidea (Trilobita, Cambrian).
Bulletin of the Peabody Museum of Natural History, Yale University, 45:1-150   PDF LINK

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Sagebrush Steve
40 minutes ago, fossilcrazy said:

Hi Sagebrush Steve,

 

Perhaps this quick identifier can help visually ID your Oaks Springs finds. If things get tricky Pete Palmer has some good publications on Cambrian Trilobites from the SW states. 

Thanks @fossilcrazy, very helpful.  From this, I would say the most likely candidate is O. fowleri.  Too bad the genal spines weren't preserved as that could have been the determining factor.  But see my comment below.

 

22 minutes ago, piranha said:
Whittington, H.B. (1989)
Olenelloid trilobites: Type species, functional morphology and higher classification.
Philosophical Transactions of the Royal Society of London, Series B, 324:111-147
 
Palmer, A.R., & Repina, L.N. (1993)
Through a glass darkly: Taxonomy, phylogeny, and biostratigraphy of the Olenellina.
University of Kansas Paleontological Contributions, New Series, 3:1-35
 
Lieberman, B.S. (1998)
Cladistic analysis of the Early Cambrian olenelloid trilobites.
Journal of Paleontology, 72(1):59-78
 
Lieberman, B.S. (1999)
Systematic revision of the Olenelloidea (Trilobita, Cambrian).
Bulletin of the Peabody Museum of Natural History, Yale University, 45:1-150

Thankss, @piranha, very helpful.  I had thought from fossilcrazy's reply that I have an O. fowleri, but that species doesn't show up in either of the papers you posted.  Oh well, I've now got plenty of reading to do, thanks!

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piranha
2 hours ago, Sagebrush Steve said:

Thankss, @piranha, very helpful.  I had thought from fossilcrazy's reply that I have an O. fowleri, but that species doesn't show up in either of the papers you posted.  Oh well, I've now got plenty of reading to do, thanks!

 

 

Here you go: Olenellus fowleri

 

text & figures from:

 

Palmer, A.R. (1998)

Terminal early Cambrian extinction of the Olenellina: documentation from the Pioche Formation, Nevada.

Journal of Paleontology, 72(4):650-672

 

IMG1.thumb.jpg.b97aedb1158b832a6d75018b276841be.jpg  IMG2.thumb.jpg.24d0b18519743657d39a35e04b808699.jpg

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Sagebrush Steve
1 hour ago, piranha said:

 

 

Here you go: Olenellus fowleri

 

text & figures from:

 

Palmer, A.R. (1998)

Terminal early Cambrian extinction of the Olenellina: documentation from the Pioche Formation, Nevada.

Journal of Paleontology, 72(4):650-672

 

IMG1.thumb.jpg.b97aedb1158b832a6d75018b276841be.jpg  IMG2.thumb.jpg.24d0b18519743657d39a35e04b808699.jpg

Thanks, another very helpful paper.  I am now hooked on Olenellus.  I will have to plan more adventures in the coming months to other localities to fill out my collection.

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