Douvilleiceras Posted October 13, 2017 Share Posted October 13, 2017 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: 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. 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. Regards, Jason "Trilobites survived for a total of three hundred million years, almost the whole duration of the Palaeozoic era: who are we johnny-come-latelies to label them as either ‘primitive’ or ‘unsuccessful’? Men have so far survived half a per cent as long." - Richard Fortey, Trilobite: Eyewitness to Evolution. Link to comment Share on other sites More sharing options...
doushantuo Posted October 13, 2017 Share Posted October 13, 2017 trilo which contains,among other things: Link to comment Share on other sites More sharing options...
Wrangellian Posted October 13, 2017 Share Posted October 13, 2017 I thought Ductina was Famennian in age...? Link to comment Share on other sites More sharing options...
Miocene_Mason Posted October 13, 2017 Share Posted October 13, 2017 Nice examples! “...whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been and are being evolved.” ~ Charles Darwin Happy hunting, Mason Link to comment Share on other sites More sharing options...
Douvilleiceras Posted October 13, 2017 Author Share Posted October 13, 2017 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. Regards, Jason "Trilobites survived for a total of three hundred million years, almost the whole duration of the Palaeozoic era: who are we johnny-come-latelies to label them as either ‘primitive’ or ‘unsuccessful’? Men have so far survived half a per cent as long." - Richard Fortey, Trilobite: Eyewitness to Evolution. Link to comment Share on other sites More sharing options...
Wrangellian Posted October 14, 2017 Share Posted October 14, 2017 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) Link to comment Share on other sites More sharing options...
doushantuo Posted October 14, 2017 Share Posted October 14, 2017 19-25: D Ductifrons Link to comment Share on other sites More sharing options...
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