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Dimitris

Can someone identify this trilobite?

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Dimitris

Hello all!

I bought this bug like 20 years ago. If I remember correct, the vendor said it comes from Russia, Ural mountain range.

Through a research, I found that there are a couple of paleozoic outrcrops in the area.

I also checked trilobite species and looks like this one belongs to Redlichiida or Corynexochida order.

These two orders have similar cephalon stracture (Cephalic doublure). The pygdium looks significant thinner than the rest of the body.

I think I can count 10 ribs on the main body.

Its total size is almost 5cm and the matrix is 7X5.5cm.

I have increased the contrast using photoshop so as more details can be seen.

Hope someone can tell me more!

 

IMG_7940.JPG

IMG_7941.JPG

IMG_7942.JPG

IMG_7943.JPG

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Tidgy's Dad

Yes, it looks like that to me too. 

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Dimitris
20 hours ago, Huntonia said:

This looks to be a Metacanthina from the devonian of Morocco :)

 

20 hours ago, Tidgy's Dad said:

Yes, it looks like that to me too. 

Guys you are amazing, thanks!

Metacanthina genus have only 3 species?

https://www.moroccotrilobites.com/metacanthina/

As per this, I would say Metacanthina issoumoursensis or Metacanthina wallacei because:

If that I see in front is a tongue, mine looks like to have it. Or it might be this "The cephalon is large with a small point in front."

I cannot tell the difference.

All have the same amount of ribs. I cannot understand the rest of the details concerning thorax.

This sentence does not apply on mine "The median spine of the pygidium is broad at the base and is barely longer than the fifth pair of lateral pygidial spines."

So I incline towards wallacei.

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Tidgy's Dad

I'm not sure about the species.:shrug:

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Dimitris
53 minutes ago, Kane said:

M. wallacei would have fine granulation on its shell, which this piece does not. 

Nice observation, thanks!

Both issoumoursensis and wallacei have granulation, so both excluded. This leaves the only option of maderensis.

I agree with this :The pygidium has a median spine that is very broad at the base and then acute at its extremity.

I don't understand what could be these rings: "The pygidial axis has 12 rings without tubercle.", though might not be preserved to observe.

 

I also don't understand this statement:

This species has a cephalon that is twice as large as long. It has a strong occipital spine.

What does it mean? The cephalon is 2X for lenght compared to width? This ration includes the genal spine? If yes, it makes sense.

 

Of course I can't determine based on the eyes since the sample is not perfect.

The eyes have 29 rows of maximum 10 lenses.

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Huntonia
1 hour ago, Dimitris said:

"The pygidial axis has 12 rings without tubercle.", though might not be preserved to observe.

Some technical terminology. All trilos are divided into three lobes. Down the middle is the axial lobe and on either side there are the right and left pleural lobes. Here's some useful diagrams, you can see in the first diagram where they've labelled the axial rings

trilomorph2007.gif.b22bf05e889789ca81816dd80f71d303.gif

Trilobite1.jpg.cb3982cb30f917fad289460255a4bc45.jpg

1 hour ago, Dimitris said:

also don't understand this statement:

This species has a cephalon that is twice as large as long. It has a strong occipital spine.

The occipital spine, sometimes called an occipital horn is a small spine that extends from the back of the cephalon, it is heavily worn on your specimen. Here's a pic I found online for reference.

20201122_114429.jpg.c65cabcaaf1471a317465229562cf416.jpg

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Dimitris
12 hours ago, Huntonia said:

Some technical terminology. All trilos are divided into three lobes. Down the middle is the axial lobe and on either side there are the right and left pleural lobes. Here's some useful diagrams, you can see in the first diagram where they've labelled the axial rings

 

The occipital spine, sometimes called an occipital horn is a small spine that extends from the back of the cephalon, it is heavily worn on your specimen. Here's a pic I found online for reference.

20201122_114429.jpg.c65cabcaaf1471a317465229562cf416.jpg

Thank you very much, found some online but noticed that the terminology used had some differences.

Nevertheless, my question refers mostly to:

"This species has a cephalon that is twice as large as long."

What does this ratio means? Lenght of the cephalon is 2 times its width?

So if the cephalon measures 2cm in width, the lenght must be ~4cm to match this species? I guess I include the lenght of the genal spine.

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