GerryK

Missouri Trilobites

161 posts in this topic

Missouri has wonderful fossils and some of them are trilobites. They are well known from the Ordovician and Carboniferous. I've been collecting Missouri trilobites and have acquired some specimens that may not be familiar to collectors. Some are complete and some are parts that I find to be very interesting. The specimens will be posted one at a time because each one for me has a story I would like to tell. One of them I hope will be a mind blower.

The first Missouri trilobite I'm posting is a rare Odontopleruida called Exallaspis cf. E. illinoiensis. It was found upside down, then I flipped and prepared it. The trilobite is articulated but the free cheeks are gone so it appears to be a moult. The specimen is illustrated in natural color and whitened to show details. The same is done for the pictures of a free cheek which is attached to a partial cranidium.

I have not found any literature stating that this trilobite occurs in Missouri. I don't know of any other articulated Exallaspis from the US. The only other articulated specimens from North America that I know of come from Anticosti Island.

I'm starting with this trilobite because I'll be taking it to MAPS and it will be given away to be described. If anyone is going to MAPS and would like to see this trilobite, stop by my table and I'll be glad to show it to you.

I want to thank Tom Whiteley for the photography.

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Edited by GerryK

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Fabulous trilobite from Missouri... Thanks for posting Gerry :)

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nice fossil, thanks for showing us.

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Spectacular Exallaspis cf. E. illinoiensis Gerry!

Have you contacted Brian Chatterton (University of Alberta) concerning this specimen? He and Rolf Ludvigsen have done some work on Anticosti trilobites and may be able to shed some light on your specimen's distribution in North America.

Thanks for sharing this with us,

Dan

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terrific story and specimen, can't wait to see the rest :)

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Really stunning!

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Wow - those are amazing. I didn't realize you could find those in Missouri. Hope to find some myself :)

thanks for sharing!

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Tom Whiteley and I got together on Sunday to photographed Missouri trilobites and I received the pics yesterday. I will not be posting any pictures until after Easter. After work on Friday I'm taking a two week vacation and heading to Missouri to collect more trilobites and go to MAPS. When I get back look for more Missouri trilobite postings.

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Tom Whiteley and I got together on Sunday to photographed Missouri trilobites and I received the pics yesterday. I will not be posting any pictures until after Easter. After work on Friday I'm taking a two week vacation and heading to Missouri to collect more trilobites and go to MAPS. When I get back look for more Missouri trilobite postings.

Marvelous bug and story :wub:

Looking forward to a lot promising continuation :bow:

Edited by astron

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AAAAAAAAAAGH-I live here, and don't have a single whole trilobite. I am oozing green.

Brent Ashcraft

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I'm lookin forward to see your latest finds especially that Dalmanites you told me about. Thanks for sharing Gerry.

mikey

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I'm now back from my 2 week field collecting trip of Missouri trilobites. The weather was beautiful, 70's and 80's each day and no rain. In the past I needed that take my winter and summer clothes due to the changes of weather. This year was very different because of the unseasonably warm weather. In past years when I collected in Missouri the Red Buds are just starting to come out. This year the Red Buds were on their way out and so many other plants were in bloom. I saw for first time The Buckeyes in bloom. I never realized that there were so many Buckeyes in Missouri. Other trees I saw blooming were the Dogwoods and Locust. There were wild flowers blooming every where. Along the creeks I saw a water snake, salamander, turtle and many different frogs making calls. The big surprise was seeing a mink. Then there were the ticks. I knew this year would be bad due the very warm weather that started very early. Even though I saw ticks crawling on my boots, I was prepared this year with 40% Deet and found none on my body. However, I did get poison ivy for the third straight year.

My main objective this year was to collect topotype specimens of 3 trilobites described from Missouri. To collect these trilobites I would need to cross several property lines to get to a site and had to get permission from land owners. I spent a whole day contacting them to get permission and they all were very nice to me. I have some examples of how nice they were. To get to one locality, which is a mile away from the road, the land owner offered to drive me the the outcrop. After collecting over 100 lbs. of rocks, I loaded them into the back of his truck and he drove me back to my vehicle. Another site is over a half mile across a pasture. The land owner offered me to use his 4 wheel electric cart to drive to the outcrop. Again I was able to collect over 100 lbs. of rock and load them into the cart and drive back to my vehicle. At another site I loaded my backpack with about 60 lbs. of rock and when I lifted it up, the strap broke. A land owner was kind to repair the strap. Such wonderful people I met.

I was very successful in collecting pygidia and cephalia of all three trilobites and once I get the material prepped out I will be able to compare them to the type specimens. I also collected some articulated specimens and have pictures of three. One is an upside down Calymene, the one in the grey rock my be a Calymene and the one in the red rock is unknown. I will eventually get to each one and will post them. I have a lot of prepping to do and it is going to be keep me busy for a long time.

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Hi,

I can't wait to see your cleaned finds !

You know, generally, when we address courteously people, they are courteous also. I sometimes obtained authorizations there where the others failed, because I explained what interested me, because I was interested in people, and because I respected them. It is the best key to open locks ! ;)

Coco

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Hi,

I can't wait to see your cleaned finds !

You know, generally, when we address courteously people, they are courteous also. I sometimes obtained authorizations there where the others failed, because I explained what interested me, because I was interested in people, and because I respected them. It is the best key to open locks ! ;)

Coco

This is all to true but unfortunately not every collector thinks the same way and those of us who do have to sometimes go back and rebuild bridges. I not only had to rebuild them but also guard them so they don’t get burned again. Gerry, you know who I’m talking about! ;) ;)

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Spiny Phacopids are known from Morocco but did you know that Missouri has a spiny Phacopid? The pictures of this Missouri, Phacopid cephalon are of a species that is not described. It is different from know Phacopid genera with genal spines, such as Viaphacops and Paciphacops, by having long slender genal spines and an occipital spine. A similar looking Phacopid is described by Hass(1969), Phacops claviger from the Wenban limestone of Nevada. It is not know if there are spines on the axial rings of the thorax of this Missouri trilobite but I hope to find out.

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I found a few papers describing the Nevada trilobite as having axial spines on alternating thoracic segments. Looking for a photo but cannot find one. Spectacular discovery... Congrats on the incredible bug Gerry :D

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Found it... mislabeled :o DOH :P

Thanks again for posting B)

 

Phacops claviger.jpg

 

RE: Lower Devonian Trilobites from Central Nevada and Northern Mexico

Journal of Paleontology, Vol. 43, No. 3 (May, 1969), pp. 641-659

Author: Winfried Haas

 

 

 

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Found it... mislabeled :o DOH :P

Thanks again for posting B)

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RE: Lower Devonian Trilobites from Central Nevada and Northern Mexico

Journal of Paleontology, Vol. 43, No. 3 (May, 1969), pp. 641-659

Author: Winfried Haas

Scott

Thanks for posting the photo. Now the two trilobites can be compared.

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I haven't been collecting trilo's very long here in the northwest corner of Missouri but in the last year, I have found quite a few, mostly pydgies, and all ameura. I wouldn't ask you for specific locations but I am curious as to what part of the state you are finding these! Great finds and I can't wait to see what they look like prepped out! :) Not unlike Ashcraft, I am green with envy! ;)

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I haven't been collecting trilo's very long here in the northwest corner of Missouri but in the last year, I have found quite a few, mostly pydgies, and all ameura. I wouldn't ask you for specific locations but I am curious as to what part of the state you are finding these! Great finds and I can't wait to see what they look like prepped out! :) Not unlike Ashcraft, I am green with envy! ;)

Go east young man go east.

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Go east young man go east.

;) Thanks! :)

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The pictures are of three Calymenids, 2 from Missouri and "celebra" from Illinois. The internal mold of "celebra" is illustrated and a latex cast is made from its external mold. Also note how the internal mold and external cast look different. The latex cast was made so comparisons can be made with the other Calymenids and one can see that all 3 Calymenids are different.

.

The history of "celebra" has assigned it to 5 genera and has been referred to Calymene, Flexicalymene, Gravicalymene, Sthenarocalymene and Apocalymene. The reason for this confusion is that this very common Silurian trilobite has a non-buttress 2p papillate lobe which makes it different from other described species of Calymene. The 2 Missouri trilobites also have a non-buttress 2p papillate lobe and I believe these 2 trilobites would form a monophyletic group with "celebra." I'm not assigning them to any genus because in my opinion this "group" still needs work in classifying them.

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Gerry,

Thanks for posting this wonderful assortment of calymenids. The process of interpreting these slight differences is no easy task. If you are planning another installment on this topic and want to add a diagnostic drawing or figures it would be useful to follow your presentation more precisely. In the meantime this homework assignment is next in line on a long list of reading to catch up on. The papers by Chestnut (2008) and Shirley (1936) appear to be a good starting point for this discussion. Any others that you can recommend are greatly appreciated.

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Gerry,

Thanks for posting this wonderful assortment of calymenids. The process of interpreting these slight differences is no easy task. If you are planning another installment on this topic and want to add a diagnostic drawing or figures it would be useful to follow your presentation more precisely. In the meantime this homework assignment is next in line on a long list of reading to catch up on. The papers by Chestnut (2008) and Shirley (1936) appear to be a good starting point for this discussion. Any others that you can recommend are greatly appreciated.

I recommend the following:

Siveter, D.J. (1976) The Middle Ordovician of the Oslo region, Norway ---- introduces Sthenarocalymene

Chatterton & Cambell (1980) Silurian trilobites from Canberra and some related forms from the Yass Basin ---- introduces Apocalymene

Holloway (1980) Middle Silurian trilobites from Arkansas and Oklahoma, U.S.A. ---- introduces Sthenarocalymene scutula

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The two papers from Schweizerbart are available to me as paper copies at the UO science library.

Wondering if either of these or the paper in Norsk Geologisk Tidsskrift is available as a pdf version?

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