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Lugo

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Freitag, 3. Januar 2014, 09:53

Preparation of a challenging one.

Hi All,

i decided to start this new year with a more challenging preparation project.
It is uncertain whether i can bring this preparation to a good end, but at least i hope to learn from it and to get valuable advise from this experienced forum during the different preparation steps.
Attached is a picture, that shows the fracture line of the shell: this visible part is 3 cm long. Most of this trilobite sits in the pictured rock.
I have two more pieces of stone ( not pictured) that contain smaller fragments. These parts will be glued on later.
Without disclosing too much, i can say that this bug has Eifelian age and she comes from the very south of Morocco.

Who gives this fellow a name?

Best regards

Luc
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Xiphogonium

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Freitag, 3. Januar 2014, 10:18

Jesus, I don't have the slightest of clues! But I will be eager to see what it is! :333:
"The gates of Heaven and Hell are adjacent ... and unmarked!" - Carl Sagan
Empfehle uns doch weiter! :201: (Klappern gehört zum Handwerk)

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3

Freitag, 3. Januar 2014, 10:35

Hi Luc, hi Mike...

I also have absolutely no idea what species of trilobite it could be... :239: But I look forward to see what our prep- specialist would see in this beautiful, wet stone... I´m sure for these guys it will be very easy to determine the exact species, for me it´s just a nice stone...

best wishes for preparation, Luc...

greetings

Micha

Jens

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Freitag, 3. Januar 2014, 13:32

Hi Lugo,

with your hints and the picture I believe to see a Ceratarges, with the head at the left and the pygidium bending upwards.
Hope I'm right. With only 3cm it's a small one.

The separation is good, but the spines made the work not easy.

all the best,
Jens
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Lugo

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Freitag, 3. Januar 2014, 17:33

Preparation of a Ceratarges sp.

Thanks for the reactions.
And as expected, Jens is spot on. Congratulations. :014:
This is indeed a Ceratarges sp. from Jbel Zireg.
I have read the Ceratarges article ( 2011 ) from Allart and Harald and i hope that based on these descriptions it is possible to come to a species determination of this bug.
For sure the attached pictures in this article will help to avoid running unexpectedly into spines.
After 4 hrs of prepping i found the left eye with it's librigena. Now i will work around the glabella to the right side of the trilo.
The bug sits in a S-shape in the matrix and this will make it more difficult to keep the genal spines supported.
But we will see how to solve this.

Best regards

Luc
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Freitag, 3. Januar 2014, 22:11

Wow, excellent! It's looking really good. I had the pleasure of visiting that site for several days on two occasions. This is a good specimen, they are not that easy to find. The contrast of the shell with the matrix is also a good sign. A dark trilobite has usually better quality. A tight fit between glabella and librigena is also a good sign.
Nowadays, the site is off limits. It's quite close to the Algerian border.

Jens

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Samstag, 4. Januar 2014, 13:47

Hi Lugo,

at the moment it's hard to know which species you have, but the morphology of all species is similar and the difficulties comparable.

You can look after the head spine, but do not remove matrix in a larger scale, because there might be spines at the occipital ring and also the second stalked eye is close to the other head-spines. If you need place to work, follow the dorsal margin and prepare the genal spine at the left side.
Then look for the occipital ring and the thorax rings. There is also a problem that the large pygidial spines are curved somewhat up and can be easily damaged when matrix is removed. There can also be secondary spines at the major spines there, which look nice when not chopped away;-)

Whish you luck, keen eyes and calm hand;-)

all the best,
Jens
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Lugo

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Sonntag, 5. Januar 2014, 10:24

First of all , thank you for the comments and advise.

But what started as an exiting preparation project ended yesterday evening as a disappointment.
When removing more matrix from the glabella to search for the two head spines, I found the glabella severely deformed. Probably through compression the left side of the glabella front was pushed partially over the right side, causing a very assymetrical glabella as you can see on the attached picture.
I decided to remove more matrix and to go for the right genal spine. Then came the next disappoinment, because the right librigena is missing. :301:
This makes this trilobite for me now an excellent piece to practice the preparation of a spiny specimen. I will see later whether it is worthwhile to post a few progress pictures of this exercise or not.

Although the disappoinment is great, these things happen and not every new project delivers a nice specimen.

Best regards

Luc
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Sonntag, 5. Januar 2014, 19:20

Hi Lugo,

so sorry that your first specimen is a problematic one, but such disappointments are nearly normal when working with such spiny trilobites. Ceratarges is known to be rarely perfect, may be one of 3 unprepared specimen will be after the prep-work in a perfect state. Udo (Schachtratte) wrote years ago about his negative experiences with this genus, only few (1 of 3) specimens he tried turned out to be good ones.

Fehlerquoten

Anyway, as you said, use this specimen to get experience, this will be fruitful for other more complicated trilobites;-) The diagenetic distortion is somewhat unusual and it looks to me that also this specimen was buried perpenticular to the bedding plane. The missing librigena seems to signalize a moulted specimen, but the found position speaks for an specimen which was rapidly burried. May be a moult which remained articulated and was then burried by sediment movements.
Jbel Zireg (not Zguilma, typo error) is somewhat difficult to interpretate taphonomical, we know clear evidence for deceased specimens and nearby moulting remains.

all the best,
Jens
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Dieser Beitrag wurde bereits 1 mal editiert, zuletzt von »Jens« (5. Januar 2014, 22:07)


Fred

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Sonntag, 5. Januar 2014, 20:57

This one is from Zireg. :201:

My limited experience with this location seems to confirm that thickness and color of the carapace are useful quality indicators. From the last picture, your specimen seems to be lighter than I imagined. Likely, a thick dark shell indicates live burial, whereas molts were thinner and lighter. Just an hypothesis.

Lugo

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Montag, 6. Januar 2014, 14:35

Hi Jens, hi Fred,

thanks for your reply and the interesting reference to Udo's experience.
As i said before, this specimen will be used for practicing and to gain experience in preparation of long freestanding spines. But i am also curious to see how this little bug will look after the preparation is complete.
That means that from time to time i will work on this specimen and if worthwhile i will post some pictures.

Best regards

Luc
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Donnerstag, 9. Januar 2014, 01:19

Hello Lugo,

sorry for my late reply but I was busy. :201:

Unfortunately it is realy difficult to get an unprepped Ceratarges with both cheeks perfect attached.
I made the same experience and thus I haven't got a single Ceratarges prepped yet.
Like Frederik told there won't be a lot of unprepped Ceratarges in the near future.
What a pitty that in the old days nobody took care about a good prepjob.
If you have a good perfect one, keep it. :108:

Hopefully a new one will be better, best regards,

Andries

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Donnerstag, 9. Januar 2014, 08:32

Hi Andries,

thanks for your reaction.
I hope that in the future i can get another specimen and maybe i have a bit more luck in that case.

We will see.

All the best

Luc
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Donnerstag, 9. Januar 2014, 11:27

Luc, I'm glad to hear you will not be giving up on this one just yet. I hope the prep of this not-so-perfect specimen will result in an interesting experience nonetheless. Maybe the rock hold a few surprises, you never know.