Roger Posted February 1, 2008 Share Posted February 1, 2008 Can some one tell me any discerning differences between S. euomphalus and S. amphiscapha?? From what I have been able to tell it appears to be size with the S. amphiscapha being much larger. Both of my specimens were collected from the Finis Shale, Pennsylvanian (Jacksboro, TX). Thanks Roger Link to comment Share on other sites More sharing options...
Members geofossil Posted February 1, 2008 Members Share Posted February 1, 2008 Archaeogastropod taxonomy is vague. Even the distinction of species among living genera of gastropods can be difficult. The difference in Straparollus would probably be in the opening shape. This, however, varies between specimens. I've found what I call 'Straparollus' in a few Upper Carboniferous formations and simply use the label Straparollus sp. 1 Link to comment Share on other sites More sharing options...
jkfoam Posted February 1, 2008 Share Posted February 1, 2008 Roger, Both "Index Fossils of North America" (Shimer and Shrock) and "Invertebrate Fossils" (Moore, Lalicker,and Fischer) show Euomphalus and Amphiscapha as Subgenus of Straparolus. Both references discuss identification differences between Euomphalus and Amphiscapha. I think Moore's discussion is more understandable from a nonprofessionals point of view. Moore says,"Amphiscapha is distinguished by its flat base, carinate whorls and concave apical (or top) surface. Euomphalus is characterized by carinae on upper angulation of whorls and a wide umbilicus. I hope this helps. JKFoam 1 The Eocene is my favorite Link to comment Share on other sites More sharing options...
Members geofossil Posted February 2, 2008 Members Share Posted February 2, 2008 Roger,Both "Index Fossils of North America" (Shimer and Shrock) and "Invertebrate Fossils" (Moore, Lalicker,and Fischer) show Euomphalus and Amphiscapha as Subgenus of Straparolus. Both references discuss identification differences between Euomphalus and Amphiscapha. I think Moore's discussion is more understandable from a nonprofessionals point of view. Moore says,"Amphiscapha is distinguished by its flat base, carinate whorls and concave apical (or top) surface. Euomphalus is characterized by carinae on upper angulation of whorls and a wide umbilicus. I hope this helps. JKFoam JK, those are good references. The genus has been revised a few times in the last couple decades since the last editions. About a decade ago I acid-bathed a bunch of similar aged gastropods out of matrix. Maybe a dozen species of gastropods and bivalves. I've rarely come across such a mishmash of taxonomy once I started to research them. Even when having detailed descriptions I couldn't get my head around them. 1 Link to comment Share on other sites More sharing options...
Roger Posted February 2, 2008 Author Share Posted February 2, 2008 Geo - thanks for the info - you are like me - I write - 'Straparollus sp.' note the place, formation, age and date and move on BUT (isn't there always a big but?!!?) I was on a website called www.catnapin.com run by some folks out Lubbock way and they have images of collected gastropods and they discerned (apparently) between the two sub genus. Therefore I figure that there must be a way to tell. Again - like you - I read some of these descriptions and have to go to a vocab list to figure out what the individual is saying. JKFoam - thank you for the description from Moore. - I have Shimer and Shrock but mine is a 13th printing and is dated 1987 and there are no notes that it has been updated since the original preface dated July 1, 1943!! However it still is a good reference to atleast point me in the right direction. I also downloaded some illustrations from the Geology Dept web site at www.geology.pitt.edu and looking at the two sub genus you can see that the top of the Euomphalus is flat but they only give an obique view of Amphiscapha so you really can't compare. Also these are illustrations not photographs. Again - thanks to both of you Roger Link to comment Share on other sites More sharing options...
Guest solius symbiosus Posted February 2, 2008 Share Posted February 2, 2008 Roger,Both "Index Fossils of North America" (Shimer and Shrock) JKFoam Wow! That brings back fond memories of the reference section. I haven't seen that in at least 20 years. Thanks Link to comment Share on other sites More sharing options...
Xiphactinus Posted February 2, 2008 Share Posted February 2, 2008 Here's a good resource for Pennsylvanian mollusk identification: http://www.lakeneosho.org/FaunaList.2.html Link to comment Share on other sites More sharing options...
Roger Posted February 2, 2008 Author Share Posted February 2, 2008 Here's a good resource for Pennsylvanian mollusk identification:http://www.lakeneosho.org/FaunaList.2.html Thank Xi - went to the site - unfortunately opened up another can o'worms. . . Trepospira has a couple of species and the images on the site are very clear as to the differences between the two; therefore now, I got to go back and look at all of my Trepospira sp specimens and see if I can sort them even further. . . <grin> thanks a lot buddy<grin>!!! Roger Link to comment Share on other sites More sharing options...
Members geofossil Posted February 2, 2008 Members Share Posted February 2, 2008 Re Trepospira Having worked in paleo for a few decades I've learned not to get too caught up in species identification and especially if not referenced directly to the original type specimen in the original publication. Here's a few 'Trepospira discoidalis' from my collection but 'Trepospira sp.' would be fine. Link to comment Share on other sites More sharing options...
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