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Douvilleiceras

Ductina - a blind phacopid trilobite

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Douvilleiceras

Hello All,

I’ve acquired some specimens of the species Ductina vietnamica, a blind phacopid trilobite from the Devonian of China and Vietnam. These specimens, dating to the Eifelian age of China, are fairly well preserved for the often-flattened and disarticulated type.

Ductina was a rather successful phacopid, being recorded throughout most of the Devonian. They are small (my examples range between 1/2 an inch to 1.2 inches), with a simple effaced pygidum and a cephalon lacking many features (such as tubercles) found in its fellow trilobites of the Family Phacopidae. Most noticeably, Ductina is blind. Blindness is a trend in several groups of trilobites, but was also present in the relatives of the well-known Eldredgeops. This secondary blindness has often been interpreted as relating to the environmental conditions that the benthic trilobites faced (Clarkson, 1967). 

 

Taxonomy:

               Class: Trilobita

               Order: Phacopida

               Suborder: Phacopina

               Superfamily: Phacopoidea

               Family: Phacopidae

               Genus: Ductina

               Species: D. vietnamica

 

Location Information:

               Country: China

               Province: Guangxi

               Formation: Unknown

 

Here are some photos showing the details:

DuctinaComplete.thumb.jpg.e8ab88a5395bdee6682f3bbc8a081a70.jpg

A photo of the most complete specimen. There is some damage on the fragile pleurae, but for the most part, it is complete. This one is about 3/4 of an inch long.

DuctinaGlabella.thumb.jpg.ac237b86b6d41e5572f61ba46acc36b2.jpg

Close-up of the glabella and thorax of a red example. This one shows glabellar furrows that are absent in many examples. The pleurae are also in good shape. 

 

Citations:

Clarkson, Euan. (1967). Environmental significance of eye reduction in trilobites and Recent arthropods. Marine Geology - MAR GEOLOGY. 5. 367-375. 10.1016/0025-3227(67)90046-1.

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doushantuo

trilo

which contains,among other things:

evis.jpg

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Wrangellian

I thought Ductina was Famennian in age...?

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WhodamanHD

Nice examples!

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Douvilleiceras
19 hours ago, Wrangellian said:

I thought Ductina was Famennian in age...?

Ductina ductifrons is Famennian. However, other species exist in the Lower and Middle Devonian. Gugel et al (2017) lists Ductina vietnamica as occurring in the Eifelian of the Nandan formation in Guangxi. 

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Wrangellian

I see.... (I can't open the first link) Last I heard these D. vietnamica were Famennian. Back to alter my labels, again...

Now I'm back to having no Famennian fossils in my collection! (that I know of)

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doushantuo

 

56jghb.jpg

ductclarkeJOMevisioptrilool.jpg

 

19-25: D Ductifrons

 

 

 

 

 

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