This is the “Fossil Friday” post #263.  Expect this to be a somewhat regular feature of the website.  We will post any fossil pictures you send in to esconi.info@gmail.com.  Please include a short description or story.  Check the #FossilFriday Twitter hash tag for contributions from around the world!

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This week’s Fossil Friday is a worm Two-fer.  This concretion was part of the Helen and her son Ted Piecko’s collection.  It was collected decades ago… likely 30 or 40+ years ago.  The large worm is Astreptoscolex anasillosus, an annelid or ringed worm (Mazon Monday #146).  It was described in 1979 by Ida Thompson in her seminal work on Mazon Creek polychaete worms – “Pennsylvanian Essex fauna of northern Illinois” in Palaeontographica Abteilung A.

The smaller one is a ribbon worm called Archisymplectes rhothon, which was described by Frederick Schram in 1973 – “Pseudocoelomates and a nemertine from the Illinois Pennsylvanian” in the Journal of Paleontology.