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Missouri Trilobites


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#141 GerryK

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Posted 03 March 2014 - 05:20 PM

I did not collect this slab because it has trilobites. I collected the rock because it had a crinoid and when I got back home and trimmed the rock, I found this cluster of trilobites. At first there were only a few trilobites exposed. As I prepped the rock,  more trilobites were found. The real surprise was finding different trilobites closely clustered together.

Does anyone want to put their trilobite skills to identify the different genera on the slab?
There is an interesting story about these trilobites.

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  • Cluster-1.jpg


#142 piranha

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Posted 03 March 2014 - 05:53 PM

Looks like calymenids, dalmanitids and the hypostome of a cheirurid.  A bunch of cheirurid hypostomes look reasonably close, which one is it?



#143 GerryK

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Posted 03 March 2014 - 09:09 PM

Looks like calymenids, dalmanitids and the hypostome of a cheirurid.  A bunch of cheirurid hypostomes look reasonably close, which one is it?

:goodjob: 

 

The calymenid is Calymene, the dalmanitid genus is uncertain and the cheirurid hypostome is Cheirurus. The hypostome is the most difficult to identify. More to come about this cluster.



#144 GerryK

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Posted 10 March 2014 - 04:50 PM

Cluster-1.jpg

 

When I found the crinoid, I was collecting in the Bailey, which has been labeled as Devonian. I believe this associated cluster of trilobites are Silurian, which goes back to the discussion about the Bailey being Devonian or Silurian. I claimed in post #99, the Calymene collected is in the Silurian part of the Bailey. From a different locality in the Bailey, I collected this Calymene with a Cheirurus, which is a Silurian trilobite. From two Bailey localities, I'm finding Silurian trilobites. Because there are Silurian trilobites in the Bailey, the Silurian-Devonian boundary in Missouri is still to be determined.

The crinoid I had originally collected with these trilobites has been prepped and is a Scyphocrinites. The same crinoid I discussed in post #99.

This cluster with the pygidium and genial spine of a large dalmanitid is one that I have not seen before. I'm planning to going back to this locality after MAPS, hoping to find more of these trilobites.



#145 GerryK

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Posted 24 March 2014 - 08:26 PM

I have been posting many Calymenids and surprised by their diversity in the Silurian of Missouri.

This post is a review of the Calymenids I found from Missouri.

 

There are 5 different "celebra" type

Apo-1-new.jpg Apo-1-new (3).jpg Apo-2.jpg Apo-4.jpg Apo-3.jpg

 

This one has 12 instead of the usual 13 thoric segments

Caly-1-1 slab 12 thor.jpg Caly 1-2-slab 12 thor.jpg

 

These are Calymene species. The first one is the oldest and the last one is the youngest.

Caly6.jpg Caly-ceph-2sp.jpg Caly-ceph-7sp.jpg Caly-ceph-6sp.jpg Caly-ceph-5sp.jpg Caly-ceph-3sp.jpg Caly-ceph-9sp.jpg Caly-ceph-4-1sp.jpg Caly-ceph-8sp.jpg


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#146 ashcraft

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Posted 25 March 2014 - 01:05 AM

Do you think they are seperate species, or natural variation within the phenotype?

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#147 GerryK

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Posted 25 March 2014 - 09:25 PM

Do you think they are seperate species, or natural variation within the phenotype?

Brent Ashcraft

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Good question and at this time there is no definitive answer without a scientific description and phylogenetic analysis.  However, I will give you my thoughts. I believe the 5 different "celebra" type are different species. I found them from different localities and separated stratigraphically and would probably hold up in a cladistic analysis.

 

These two appear to show some variation in the species.

Caly-1-1 slab 12 thor.jpg Caly 1-2-slab 12 thor.jpg

 

These three are either one variable species or two or three species.

Caly-ceph-2sp.jpg Caly-ceph-7sp.jpg Caly-ceph-6sp.jpg

 

This one will be described as a new species.

Caly6.jpg

 

These two are close and may be one or two species.

Caly-ceph-5sp.jpg Caly-ceph-3sp.jpg

 

The remaining are different species of Calymene.


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#148 Auspex

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Posted 26 March 2014 - 07:20 AM

These could show Punctuated Equilibrium (or at least Peripatric Speciation) at work. What is the separation in time and space of these specimens?


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#149 GerryK

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Posted 26 March 2014 - 02:53 PM

These could show Punctuated Equilibrium (or at least Peripatric Speciation) at work. What is the separation in time and space of these specimens?

They are all Silurian. The oldest is from the Aeronian Stage of the Llandovery Series to the top of the Pridolian Series. The rock units are Sexton Creek, Bainbridge and Bailey.



#150 GerryK

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Posted 27 March 2014 - 04:59 PM

For years I have been collecting Missouri trilobites and found many Silurian dalmanitid trilobites. Some of them are posted here with their cephalon and pygidium. I've had to be careful to collect single beds to make sure the disarticulated parts belong to the same species. I have more isolated pygidia without the associated cephala and I have one cephalon and no pygidium to go with it. There are six Silurian dalmanitid trilobites described from Missouri and have only found three of them. The remaining described dalmanitids I can't place with certain with the specimens I'm posting. I am surprised by the great number and diversity of Silurian dalmanitids from Missouri.

 

Dalman-10copy.jpg Dalman-7 copy.jpg Dalman-6 copy.jpg Dalman-2.jpg Dalman-3.jpg Dalman-8 copy.jpg Dalman-4 copy.jpg 3.jpg Dalman-5 copy.jpg Dalman-9copy.jpg Dalman-1 copy.jpg

 

Last two on next post.


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#151 GerryK

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Posted 27 March 2014 - 04:59 PM

The last two.

 

Dalman-11copy copy.jpg Dalman-12copy .jpg



#152 piranha

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Posted 27 March 2014 - 05:37 PM

Congrats on the Trilobite Treasure Trove!2722.gif 2722.gif 2722.gif  :fistbump:

 

I'm curious about the stratigraphic context on the Prosocephalus.  How does the latest Pridolian square with Campbell's Emsian age for the Oklahoma examples?

 

 

 



#153 GerryK

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Posted 29 March 2014 - 08:34 PM

Congrats on the Trilobite Treasure Trove!2722.gif 2722.gif 2722.gif  :fistbump:

 

I'm curious about the stratigraphic context on the Prosocephalus.  How does the latest Pridolian square with Campbell's Emsian age for the Oklahoma examples?

 

 

 

Prosocephalus tridentifera and Prosocephalus palacea are found together in the lower Bailey. This gets back to my #99 post about where the Silurian/Devonian boundary is in Missouri. Some authors have it in the Bailey but there is no Golden Spike.  Prosocephalus xylabion is in the Bois d'Arc (Fittstown Member) Gedinnian age (not Emsian) Campbell (1977).
As to how the age of the Missouri trilobites correlate with the Oklahoma trilobites is unknown at this time. Looking at Prosocephalus tridentifera and Prosocephalus xylabion and how similar they are, one would think they are very close in age.



#154 piranha

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Posted 29 March 2014 - 08:59 PM

Thanks for clarifying that, at least the latest Silurian is not as difficult to reconcile with the base of the Devonian. 

 

These incredible calymenids and dalmanitids are certainly a great opportunity for an important new paper! emo73.gif  :P



#155 GerryK

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Posted 26 April 2014 - 10:07 AM

After MAPS I spent a week collecting and found a couple of new arthropods from Missouri.

Scorpian2.jpg Scorpian.jpg



#156 ashcraft

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Posted 26 April 2014 - 12:30 PM

Living fossils. I get a few brought in to school every year. They are relics from a much dryer time in Missouri history, still surviving on dry rocky outcrops. Their oasis in the middle of inhospitable conditions. (forests). Keep your eyes open in such areas, and you might even see tarantulas.

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#157 GerryK

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Posted 28 April 2014 - 09:55 AM

Living fossils. I get a few brought in to school every year. They are relics from a much dryer time in Missouri history, still surviving on dry rocky outcrops. Their oasis in the middle of inhospitable conditions. (forests). Keep your eyes open in such areas, and you might even see tarantulas.

fkaa

In all the years collecting in Missouri, I've never seen any scorpions. Then I find two on the same day (a dry rocky outcrop). Now you say there are tarantulas. emo37.gif



#158 ashcraft

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Posted 28 April 2014 - 10:19 AM

I have had two brought in to school in the past 7 years.  One was quite large, nearly hand sized.  My biggest concern are copperheads, flipped over a number of rocks to find them giving me the stink-eye.  We had a local guy have one in his tent this last summer, he "tried to do the right thing" and shoo it out.  He got a severe bite, which he eventually died from.  Second confirmed fatality (ever) of a copperhead bite in Missouri that I am aware of.

 

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#159 mikeymig

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Posted 01 May 2014 - 10:44 AM

Gerry, Thank you for including us on your "Missouri Trilobite Saga". I have learned a lot reading your post and your passion is obvious and appreciated. I can see a life time or more of work that needs to be done in this area of the US. If you need help digging the next time you go please don't hesitate to ask me. You know about my field experience and two diggers are better then one. Keep us updated on your discoveries and post more photos soon!

 

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#160 GerryK

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Posted 17 May 2014 - 03:25 PM

When I started this topic over 2 years ago, I stated that one of the trilobites I hoped would be a mind blower. It's time to post the trilobite, a Ceraurus from Missouri with soft parts preserved. One of the enlarged pictures shows both antenna and another shows the legs. This trilobite puts Missouri as another site where soft body parts of trilobites are preserved. I'm posting the trilobite here first for those who follow this topic. I will repost this amazing trilobite later under its own topic.

 

Ceraurus - append.jpg antenne2 copy.jpg Ceraurus - append2.jpg


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