Kentuckiana Mike Posted October 27, 2010 Share Posted October 27, 2010 Can anyone identify this trilobite cephalon? It was found in the Waldron Shale of Clark County, Indiana. The time period would be Middle Silurian Period (428-422 million years ago). I think it might be an Arctinurus but I have also been told it might be a Lichas. What I find interesting about this fossil is the large scoop in the front. The matrix is starting to break up as can been seen with the crack going through one side of the cephalon. After the picture was taken I glued the fissure in hopes to keeping it from breaking off. Hopefully the fossil will be strong enough to endure some air abrasive cleaning that could reveal more surface details. Thanks to anyone who has an opinion to this fossil's identification. Link to comment Share on other sites More sharing options...
Roz Posted October 28, 2010 Share Posted October 28, 2010 I'm afraid I cannot help with the ID. In the last 2 pics, what is that in the lower part of the pic, almost dead center? It looks like an echinoid almost.. but wrong time, curious.. Welcome to the forum! Link to comment Share on other sites More sharing options...
Auspex Posted October 28, 2010 Share Posted October 28, 2010 ...In the last 2 pics, what is that in the lower part of the pic, almost dead center? It looks like an echinoid almost... I think it's the first "rib" from the center of the thorax. The ornamentation is pretty cool! "There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant “Try to learn something about everything and everything about something.” - Thomas Henry Huxley >Paleontology is an evolving science. >May your wonders never cease! Link to comment Share on other sites More sharing options...
Shamalama Posted October 28, 2010 Share Posted October 28, 2010 Nice cephalon there Mike. The bumpy pustules are really cool and may help ID the critter. -Dave __________________________________________________ Geologists on the whole are inconsistent drivers. When a roadcut presents itself, they tend to lurch and weave. To them, the roadcut is a portal, a fragment of a regional story, a proscenium arch that leads their imaginations into the earth and through the surrounding terrain. - John McPheeIf I'm going to drive safely, I can't do geology. - John McPheeCheck out my Blog for more fossils I've found: http://viewsofthemahantango.blogspot.com/ Link to comment Share on other sites More sharing options...
Scylla Posted October 28, 2010 Share Posted October 28, 2010 That disk looks like it is not part of the cephalon, could it be the ptyrigium on an enrolled bug? Or part of a completely different fossil? Link to comment Share on other sites More sharing options...
RCFossils Posted October 28, 2010 Share Posted October 28, 2010 Looks a bit like dalmanites halli Link to comment Share on other sites More sharing options...
Caleb Posted October 28, 2010 Share Posted October 28, 2010 I would call it Arctinurus occidentalis. Here is a link to a picture of a cephalon found in the Waldron Shale. http://www.uky.edu/OtherOrgs/KPS/images/arctin3.jpg Caleb Midwestpaleo.com Link to comment Share on other sites More sharing options...
Roadcut1 Posted October 28, 2010 Share Posted October 28, 2010 I think Caleb nailed it for you. The item mentioned by Roz is the occipital ring at the back of the head. Unfortunately it isn't preserved on the photo that is linked too. Link to comment Share on other sites More sharing options...
Kentuckiana Mike Posted October 29, 2010 Author Share Posted October 29, 2010 Thank you to every one who commented. The picture Caleb found points to it being an Arctinurus. After studying the fossil under 20x magnification, most of the cephalon is coated in a thin layer of bryozoan. So it had been at least partial exposed on the sea floor for a colony of bryozoans to take up residence. Also found with the Arctinurus was part of a Dalmanites cephalon in the Waldron Shale. See attached images. It has yet to be prepped and it is falling apart as well. Link to comment Share on other sites More sharing options...
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