My trilobite of the week.

[rew]

So far I have posted many members of the family Acastidae.  All have been from the early or middle Devonian, which was the heyday of the Acastidae, although some trilobites in that family did live into the Frasnian.  But like other Devonian trilobite families this family had its origins prior to the Devonian.  Here, with trilobite #171, I show my only Silurian member of the Acastidae -- Acastocephala macrops of Middle Silurian age from the Wenlock Series of the Coalbrookdale Formation at Coalbrookdale, Shropshire, England.  It's a rather plain trilobite that doubtless had no conception of the fantastic forms that descendants of its family would take on.

 

In the background of the middle picture is the partial pygidium of a Dalmanitid trilobite.  Unfortunately the rest of that trilobite is not present.

[ClearLake]

Another interesting one.  Every now and then I just like to scroll back through this thread to see the wonderful array of trilobites.  I hope your collection still has many more to go!

[piranha]

21 hours ago, rew said:

Acastocephala macrops of Middle Silurian age from the Wenlock Series of the Coalbrookdale Formation at Coalbrookdale, Shropshire, England.

   

 

 

Acastocephala macrops has many more eye lenses than this one.  Instead this specimen matches better with another Coalbrookdale acastid trilobite: Acastoides constricta.  Although A. constricta  also has more eye lenses, according to Shergold 1966, this species has a close relationship to Acastoides henni henni  Richter & Richter 1952, differentiated by a greater number of lenses; a maximum of up to 7 lenses in any lens file compared with 4 per lens file in A. henni henni.

 

Pending any possible future description you could give it a tentative label: Acastoides sp. (aff. A. henni henni Richter & Richter 1952)

 

 

Richter, R., Richter, E. 1952

Phacopacea von der Grenze Emsium/Eiflium (Tril.).

[Phacopacea from the Emsian/Eiflian Boundary (Tril.).]

Senckenbergiana Lethaea, 33:79-107

 

Shergold, J.H. 1966

A Revision of Acaste downingiae (Murchison) and Related Trilobites.

Palaeontology, 9(2):183-207  PDF LINK

[rew]

Note to self:  Don't even bother to label a trilobite until I post it here and Piranha tells me what I got wrong.  The eyes do look like a close match for Acastoides henni henni.

Edited April 17, 2021 by rew

[piranha]

The low lens count eyes are also similar to various other species of Acastoides.  Because A. henni henni is Devonian, this appears to be an undescribed species.

 

Here is another similar example from the "Acastoides henni-Gruppe" of the Devonian of Germany:

 

Basse, M., Müller, P. 2016

Trilobiten aus dem Ober-Emsium und Frühen Eifelium der Südlichen Lahnmulde (Rupbach-Schiefer, Leun-Schiefer und Ballersbach-Kalk).

[Trilobites from the Upper Emsian and the Early Eifelian of the Southern Lahn Syncline (Rupbach Shale, Leun Shale, and Ballersbach Limestone).]

Abhandlungen der Senckenberg Gesellschaft für Naturforschung, 572:1-329

[rew]

15 hours ago, ClearLake said:

Another interesting one.  Every now and then I just like to scroll back through this thread to see the wonderful array of trilobites.  I hope your collection still has many more to go!

I'm glad you like it.  There's still many trilobites to photograph.  And still more misidentifications that need to be clarified by Piranha.

Edited April 18, 2021 by rew

[rew]

Trilobite of the week #172 is Dalejeproetus sagaouii of Early Devonian (Pragian) age from the Lhandar Formation at Mrakib, Ma'der, Morocco.  This was an inexpensive proetid that I bought just to round out  the collection.  Being bent over, it was a bother to photograph (it's always easier to photograph the prone trilobites), and I considered the preparation to be acceptable but nothing special.  So I was pleasantly surprised to see that the lenses of the holochroal eyes are mostly preserved.  In fact, these are the best preserved eyes I've ever seen on a proetid.

 

[Sjfriend]

More great bugs!

 

Thinking about all of @piranha's "corrections" it's too bad back at the beginninwe of this thread we didn't start a betting pool (to raise funds for all your new labels ) of just how many he would change

[rew]

Trilobite of the week #173 is Tamdaspis jingxiensis of Late Cambrian age from the Sandu Formation at Guole, Guangxi Province, China.  This is the only trilobite I have in the family Ceratopygidae within the superfamily Asaphoidea.  This is another modest priced bug I got to expand the diversity of my collection.

 

 

[rew]

Trilobite of the week #174 is Ductina ductifrons, of Late Devonian age and from Oberbergisches Land, Wuppertal, Germany.  Although members of the family Phacopidae are famous for having prominent schizochroal eyes, with readily visible lenses, the trilobites in the Ductina genus have no eyes and were blind.

 

I took this photograph in the usual away, and aside from the photo stacking that has been done for all of my pictures, there was no fancy post processing.  Yet, thanks to the coloration of the bug and the surrounding rock, this photo looks more like a painting.

 

 

[rew]

Trilobite of the week #175 is Acernaspis orestes an Early Silurian member of the Phacopidae from the Jupiter Formation in Northeast Quebec.  This is a small bug but at least it has eyes.  The lenses are barely visible to the naked eye only because the trilobite itself is so small (about 1.8 cm).  There is an itty bitty baby Acernaspis to the left of the main specimen.

 

The earliest members of the Phacopidae are from the late Ordovician, but the earliest member of that family in my collection is this one.

[rew]

Trilobite of the week #176 is an earlier acastid  than the Acastoides shown last month.  It is a Late Ordovician trilobite very similar to the Czech trilobite Sokhretia solitaria, but is from Tisserdmine, Morocco.  So I just have this one listed as Sokhretia sp.  I've seen several of these multiple plates for sale, apparently someone hit the mother lode.  Most of the trilobites have preserved lenses in the eyes.  The two close up trilobites are the leftmost and next to the leftmost specimens on the plate, the first eye close up is the left eye of the next to the leftmost specimen, and the second eye close up is the left eye of the uppermost trilobite on the right.

 

 

[rew]

Trilobite of the week #177 is Miraspis mira, of Silurian age, from the Liteň Formation at Lodenice, Czech Republic.  This is one of those bugs that is really hard to get an excellent specimen of.  This one is okay, not excellent.  This is an Odontopleurid similar to Koneprusia.  You can see the small spines on the free cheeks, a common (but not universal) feature of trilobites in the Odontopleuridae.  Particularly on the right side you can see that there are short spines with cross spines and long spines without cross spines.  Although these are all squashed into the same plane, from its more 3-D cousins we can assume the spines with cross spines pointed down and the longer spines went out and upward.  The living trilobite also had a pair of occipital spines, although they aren't preserved in this or most other specimens.  The eyes on short stalks are not present either.

 

 

[piranha]

On 5/2/2021 at 5:55 PM, rew said:

Trilobite of the week #173 is Tamdaspis gingxiensis

Tamdaspis jingxiensis

 

9 hours ago, rew said:

Trilobite of the week #177 is Mirapsis mira

Miraspis mira

[rew]

Okay, fixed.  One was a typo, the other was a misspelling.  I'll have to change the label on the Tamdaspis, but the Miraspis is labeled correctly.  If I ever write a book I'll have to make piranha the editor.

Edited May 29, 2021 by rew

[rew]

Trilobite of the week #178 is Acadoparadoxides levisetti, of Middle Cambrian age from the Jbel Wawrmast Formation in Alnif, Morocco.  This was named after physicist and trilobite aficionado Riccardo Levi-Setti, who wrote three popular books about trilobites and coauthored a technical paper about their visual system (https://www.nature.com/articles/254663a0).  His favorite order was the Redlichida, so it was appropriate that one of its species was named after him.

 

 

 

[rew]

Trilobite of the week #179 is Dubhglasina yunnanensis, a member of the Harpetidae of Ordovician Age from Baoshan, Yunnan Province, China.

 

 

[rew]

Trilobite of the week #180 is Ellipsocephalus hoffi of Middle Cambrian age from the Jince Formation at Jince, Czech Republic.  This is an eyeless, blind trilobite.

 

 

[rew]

Bonus trilobite #181 is Ductina vietnamica of Middle Devonian age from the Nandan Formation of Guangxi Province, China.  Like its German cousin, this is an eyeless, blind member of the Phacopidae.  I promise that any more members of the Phacopidae I show you will have eyes.

 

 

[Paleorunner]

congratulations, for such an extensive and fantastic collection of trilobites.
Thank you very much for sharing it.
I will continue to enter to see them more carefully.

[rew]

Trilobite of the week #182 is Prionocheilus cf. pulchrum (= Pharostoma cf. pulchrum) of Middle Ordovician age from the Hope Shales, Shelve Inlier at Minsterley, West Shropshire, England.  This is in the family Pharostomatidae.  If you identified this as a Calymenid you weren't too far off -- the Calymenidae is a sister group, both are in the superfamily Calymenoidea.

[rew]

On 6/25/2021 at 5:36 PM, Paleorunner said:

congratulations, for such an extensive and fantastic collection of trilobites.
Thank you very much for sharing it.
I will continue to enter to see them more carefully.

 

You're welcome.  There are more to come.

Edited June 28, 2021 by rew

[Kane]

On 6/24/2021 at 9:17 PM, rew said:

Bonus trilobite #181 is Ductina vietnamica of Middle Devonian age from the Nandan Formation of Guangxi Province, China.  Like its German cousin, this is an eyeless, blind member of the Phacopidae.  I promise that any more members of the Phacopidae I show you will have eyes.

 

 

 

This one follows Chlupáč (1977) to be Illaenula vietnamica. 

 

See:

Jell, P.A. & Adrain, J.M. 30 8 2002: Available generic names for trilobites. Memoirs of the Queensland Museum 48(2): 331-553. PDF LINK

[rew]

Is Ductina ductifrons now Illaenula ductifrons? 

 

 

[rew]

Trilobite of the week #183 is Malvinella buddeae, of Early Devonian age from the Sica Formation at Sica, Bolivia.  This is my favorite member of the Calmoniidae.  The glabella has numerous tubercles and there are sharp nodes over much of the thorax.  Looking at the counterpart, my guess is that those sharp nodes are the bases of spines that got stuck in the counterpart.  We'll know for sure if anyone ever does an air abrasion prep of one of these bugs, instead of just cracking open the concretion.

 

These bugs are found 4000 feet up the slopes of the Andes, a reminder that the Andes are relatively new mountains that are thrusting up land that was sea floor 400 million years ago.

 

 

Edited July 4, 2021 by rew