koltmanns1 Posted February 19, 2014 Share Posted February 19, 2014 Third fossil, not sure what it is. I included 3 different pictures of same fossil Link to comment Share on other sites More sharing options...
Tethys Posted February 19, 2014 Share Posted February 19, 2014 That is an iron concretion. They are very common in the Platteville. Link to comment Share on other sites More sharing options...
Cam28 Posted February 19, 2014 Share Posted February 19, 2014 (edited) Interesting, thought at first it resembled a crab. Edited February 19, 2014 by Cam28 Link to comment Share on other sites More sharing options...
piranha Posted February 19, 2014 Share Posted February 19, 2014 This one is difficult to evaluate from the photographic angles provided. After reorienting and enhancing image 3 it becomes apparent this is the internal mould of the cranidium of the illaenid trilobite: Thaleops. One of the distinct features of a Thaleops cranidium are crescent-shaped lunettes; defined on dorsal surface both as expansion of axial furrows and disruption of ornament (Amati & Westrop, 2004). Attached for additional comparison are some figures of Thaleops sp. cranidia (DeMott et al., 1987) that illustrate this feature with highlighted arrows showing the lunettes on each of the specimens. Amati, L., & Westrop, S.R. (2004) A systematic revision of Thaleops (Trilobita: Illaenidae) with new species form the middle and late Ordovician of Oklahoma and New York. Journal of Systematic Palaeontology, 2(3):207-256 DeMott, L.L., Sloan, R.E., Shaw, F.C., & Tripp, R.P. (1987) Platteville and Decorah trilobites from Illinois and Wisconsin. (63-98) In: Sloan, R.E. (Ed.) Middle and Late Ordovician Lithostratigraphy and Biostratigraphy of the Upper Mississippi Valley. Minnesota Geological Survey, Report of Investigations, 35:1-232 2 Link to comment Share on other sites More sharing options...
Xiphactinus Posted February 19, 2014 Share Posted February 19, 2014 Yea...I'm seeing trilobite too. There's too much symmetry for it to be a simple concretion. Link to comment Share on other sites More sharing options...
cowsharks Posted February 19, 2014 Share Posted February 19, 2014 This one is difficult to evaluate from the photographic angles provided. After reorienting and enhancing image 3 it becomes apparent this is the internal mould of the cranidium of the illaenid trilobite: Thaleops. One of the distinct features of a Thaleops cranidium are crescent-shaped lunettes; defined on dorsal surface both as expansion of axial furrows and disruption of ornament (Amati & Westrop, 2004). Attached for additional comparison are some figures of Thaleops sp. cranidia (DeMott et al., 1987) that illustrate this feature with highlighted arrows showing the lunettes on each of the specimens. IMG1.jpg Amati, L., & Westrop, S.R. (2004) A systematic revision of Thaleops (Trilobita: Illaenidae) with new species form the middle and late Ordovician of Oklahoma and New York. Journal of Systematic Palaeontology, 2(3):207-256 DeMott, L.L., Sloan, R.E., Shaw, F.C., & Tripp, R.P. (1987) Platteville and Decorah trilobites from Illinois and Wisconsin. (63-98) In: Sloan, R.E. (Ed.) Middle and Late Ordovician Lithostratigraphy and Biostratigraphy of the Upper Mississippi Valley. Minnesota Geological Survey, Report of Investigations, 35:1-232 Wow dude, you're good! I was sold on iron concretion, but then again, I know nothing about trilo's. Good eye(s) Daryl. Link to comment Share on other sites More sharing options...
mkrofdrms Posted February 19, 2014 Share Posted February 19, 2014 This one is difficult to evaluate from the photographic angles provided. After reorienting and enhancing image 3 it becomes apparent this is the internal mould of the cranidium of the illaenid trilobite: Thaleops. One of the distinct features of a Thaleops cranidium are crescent-shaped lunettes; defined on dorsal surface both as expansion of axial furrows and disruption of ornament (Amati & Westrop, 2004). Attached for additional comparison are some figures of Thaleops sp. cranidia (DeMott et al., 1987) that illustrate this feature with highlighted arrows showing the lunettes on each of the specimens. IMG1.jpg Amati, L., & Westrop, S.R. (2004) A systematic revision of Thaleops (Trilobita: Illaenidae) with new species form the middle and late Ordovician of Oklahoma and New York. Journal of Systematic Palaeontology, 2(3):207-256 DeMott, L.L., Sloan, R.E., Shaw, F.C., & Tripp, R.P. (1987) Platteville and Decorah trilobites from Illinois and Wisconsin. (63-98) In: Sloan, R.E. (Ed.) Middle and Late Ordovician Lithostratigraphy and Biostratigraphy of the Upper Mississippi Valley. Minnesota Geological Survey, Report of Investigations, 35:1-232 I'm amazed... I'm not worthy, I'm not worthy... Thanks Piranha. I only know about teeth, just because they are pointy and sometimes sharp. That was a real education. MK Link to comment Share on other sites More sharing options...
Tethys Posted February 19, 2014 Share Posted February 19, 2014 Wow, looking at the enhanced photo I take back the concretion ID. I have never found any trilobites, just brachiopods, stromatolites, and an occasional pelycypod. *adds yet another title to the books I must procure list* Link to comment Share on other sites More sharing options...
cowgirlfossils Posted February 19, 2014 Share Posted February 19, 2014 Welcome! Very cool. You just never know what you'll find! Sometimes nothing turns into really something! Good luck and continued happy hunting! Link to comment Share on other sites More sharing options...
Pliosaur Posted February 20, 2014 Share Posted February 20, 2014 Very cool!!! Most likely a trilobite. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now