minnbuckeye Posted March 29, 2020 Share Posted March 29, 2020 I discovered these two rollers in Fayette County , Iowa in the lower Maquoketa, Ordovician. This location is well known for Anatophrus borreaus trilobites. Though the next lower formation changes abruptly to almost 100% Isotelus. Did I find one of each? Rollers make IDs tough on me. Then as long as you "trilo" experts are looking, can you ID the trilo-bits 1,2 and 3 in the next picture? Thanks for helping!! 1 Link to comment Share on other sites More sharing options...
GeschWhat Posted March 29, 2020 Share Posted March 29, 2020 Kermits are so cute. 1 Lori www.areallycrappystory.com/fossils www.facebook.com/fossilpoo Link to comment Share on other sites More sharing options...
aek Posted March 30, 2020 Share Posted March 30, 2020 I would say #1 is Isotelus as it has more pronounced axial furrows, but I could be wrong. Link to comment Share on other sites More sharing options...
minnbuckeye Posted March 30, 2020 Author Share Posted March 30, 2020 31 minutes ago, aek said: more pronounced axial furrows That is what made me question the ID. @piranha hopefully can take a peak. Link to comment Share on other sites More sharing options...
piranha Posted March 30, 2020 Share Posted March 30, 2020 Isotelus looks good on specimen 1 because it has a narrower axial lobe. Anataphrus Whittington 1954 original description: "proposed for asaphid trilobites in which axial furrows are absent" However, subsequent authors have described the presence of axial furrows as 'essentially devoid' or 'weakly effaced' Anataphrus with axial furrows: Whittington, H.B. 1954. Ordovician Trilobites from Silliman's Fossil Mount. pp. 119-141 Ordovician Cephalopod Fauna of Baffin Island. Geological Society of America Memoir, 62:1-234 4 Link to comment Share on other sites More sharing options...
piranha Posted March 30, 2020 Share Posted March 30, 2020 The hypostome of Calyptaulax also has similar features compared to a cheirurid hypostome. The posted specimen has shoulders highlighted by the arrows. Fig. 1 Calyptaulax strasburgensis does not have shoulders although many pterygometopids do have prominent shoulders. Noting the compatible color and preservation, the hypostome could be Calyptaulax sp. Jacobs, G.S., Carlucci, J.R. 2019. Ontogeny and shape change of the phacopid trilobite Calyptaulax. Journal of Paleontology, 93(6):1105-1125 PDF LINK 2 Link to comment Share on other sites More sharing options...
minnbuckeye Posted March 31, 2020 Author Share Posted March 31, 2020 @aek, We were correct!!!! Thanks so much, @piranha. Your insight into trilobites is always impressive! Mike 1 Link to comment Share on other sites More sharing options...
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