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Partial Trilobites to ID Please


minnbuckeye

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Just putting away my trilobite finds for the winter and decided to try to place a name with a face to a few, well a dozen , of my unknowns. Most of these were found in SW Wisconsin in the Mifflin of the Platteville Formation, Ordovician. It seems very difficult to ID trilobites when they present themselves as partials. These are not beautiful specimens, but knowing their ID can help me with future hunts. Thanks for any help.   

 

1.  Are these Thaleops or Illaenus cephalons? I can not figure out how to differentiate.

 

DSC_0309.thumb.JPG.42150007a8ab08a939052c38c5552439.JPG 

 

 

2. Is this a pygidium? If so, it is quite large. Any thoughts on how to label this?

 

DSC_0310.thumb.JPG.25ef8cb59a45fdd8f703b8ad5af14b5d.JPG 

 

 

3. What is the ID for the two partial cephalons with what looks like an eye on each one?

 

DSC_0313.thumb.JPG.fdd28f08f9cc9498f64eb4345be4a64f.JPG 

 

 

 

4. Is this a hypostome from Basiliella barrandi?

 

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5. Can't place these pygidiums . Kinda isotoleus but kind of bumastus. Actually I have no idea!!! These actually came from the Maquoketa, not Platteville.

 

 DSC_0316.thumb.JPG.8b599d058315e4a3e0e459c50fe7eca8.JPG

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I am half done, I promise!!

 

6. This cephalon came from the Galena/ Ordovician of Iowa, not Wisconsin Platteville.

 

 DSC_0322.thumb.JPG.69b1e403e2938da3ebe8de3e38e10090.JPG 

 

7. Guessing a part of an Isotelus cephalon??DSC_0320.thumb.JPG.f458c5ddc7c0b5589760513abde70d86.JPG  

 

 

 8. I almost did not see this VERY TINY hypostome. It has the texture of Isotelus but is so small. A baby Isotelus??

 

 DSC_0319.thumb.JPG.2a3fd777b3165ac04b0a3677c97f0bc9.JPG 

 

 

 9. I always find many fairly round pygidiums in the Platteville. Are they a single species or is it impossible to tell such non-descript pygidiums?

 

 

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10. Finally, a shot in the dark. Initially, I noticed a sliver of trilobite of the consistency of an Isotelus and was going to pitch this. However, I did work on it a little and all at once my mind began to envision an eye on a stalk of a trilobite. People see weird things in rocks all the time. I am probably in their company with this one!! Reminds me of the Russian trilobite, Neoasaphus

 

DSC_0318.thumb.JPG.16b0368c2577dff1753984759a0559df.JPG 

 

@piranha

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DSC_0309.thumb.JPG.42150007a8ab08a939052c38c5552439.JPG  Thaleops ovata

 

DSC_0310.thumb.JPG.25ef8cb59a45fdd8f703b8ad5af14b5d.JPG  Thaleops cranidium

 

DSC_0313.thumb.JPG.fdd28f08f9cc9498f64eb4345be4a64f.JPG  cheirurid sp.

 

IMG2.jpg.0ef8e1bdf44964a9d3ebaa039befbfc7.jpg  Isotelus sp.

 

IMG1.jpg.5cbd1cce354a2c26bc042480126acb2b.jpg  Basiliella barrandei

 

DSC_0316.thumb.JPG.8b599d058315e4a3e0e459c50fe7eca8.JPG  Anataphrus vigilans

 

DSC_0322.thumb.JPG.69b1e403e2938da3ebe8de3e38e10090.JPG  cheirurid sp.

 

DSC_0319.thumb.JPG.2a3fd777b3165ac04b0a3677c97f0bc9.JPG  Isotelus sp.

 

DSC_0317.thumb.JPG.30d8e9a139f5f40dab1c77accbab172f.JPG  Ectenaspis homalonotoides / Failleana indeterminatus

 

DSC_0318.thumb.JPG.16b0368c2577dff1753984759a0559df.JPG  Ectenaspis beckeri 

 

IMG.thumb.jpg.d56f4ab6f42c5e829735964f643f40d7.jpg  Ectenaspis beckeri 

image.png.a84de26dad44fb03836a743755df237c.png

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Thanks @piranha. Much, much help. Do have a few questions though. The images of Isotelus hypostomes that I checked on line all seem to have wrinkly lines running through them. This hypostome is relatively smooth and has 2 definite, though hard to see in this photo, depressions where the chips in my specimen are, very similar to the Basiliella pictured.  How can I understand how to tell the two apart??

 IMG2.jpg.0ef8e1bdf44964a9d3ebaa039befbfc7.jpg  Isotelus ?

 

IMG1.jpg.5cbd1cce354a2c26bc042480126acb2b.jpg  Basiliella barrandei

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1 hour ago, minnbuckeye said:

Thanks @piranha. Much, much help. Do have a few questions though. The images of Isotelus hypostomes that I checked on line all seem to have wrinkly lines running through them. This hypostome is relatively smooth and has 2 definite, though hard to see in this photo, depressions where the chips in my specimen are, very similar to the Basiliella pictured.  How can I understand how to tell the two apart??

 

 

Coincidentally, I also thought those marks were interesting and initially marked it Basiliella?
When compared to another Basiliella hypostome, I could not convince myself they matched.

 

IMG.jpg.3621f15a3a869985408b1b9b70e2c39f.jpg

 

 

Additionally, it is not unusual to find Isotelus hypostomes with indistinct terracing. 

Another possiblitiy is Ectenaspis.  You can best decide with the specimen in hand.

 

IMG1.jpg.3ca403e6d21a9b13b4589fc486f1328d.jpg

image.png.a84de26dad44fb03836a743755df237c.png

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I found another comparison photo of Basiliella barrandei.  The median body has prominent furrows, but your specimen may have a more flattened aspect.

 

IMG.jpg.5aa67d1f210304db1d12a4713651de88.jpg

image.png.a84de26dad44fb03836a743755df237c.png

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Lane/Thomas's *review of scutelloids contains some remarks on isotelid hypostomes and their ontogeny ,I seem to recall

*(Sp.paper Paleontol.,1983)

allifernakristlanthc.jpg

 

 

 

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9 hours ago, doushantuo said:

 

Lane/Thomas's *review of scutelloids contains some remarks on isotelid hypostomes and their ontogeny ,I seem to recall

 

 

This is another very informative publication. Unfortunately it is often the case when I read the wealth of info gathered within an article like this I end up more confused than when I started. This is why @doushantuo and @piranha must be utilized from time to time. Thanks.

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