davehunt Posted August 26, 2009 Share Posted August 26, 2009 This fossil is still puzzling me. Any ideas? This was found in Geneva Pass in SE Idaho at a road cut on Highway 89 through a giant shale bed. According to a geologist's report I was looking at, this is a “Jurassic Twin Creek Limestone (cleaved, locally gypsiferous or fossiliferous, and generally fine-grained), and green shale … and contains calcareous shale with wind ripples, mudcracks and rip-up clasts, plus abundant trace fossils, all representing a periodically exposed west-facing Jurassic carbonate margin” (Fortsch & Link: 289). I've tried a couple different angles hoping the shadows will show up. The third image has some highlighting of one of the most interesting outlines, IMO. Thanks Dave Link to comment Share on other sites More sharing options...
lordpiney Posted August 26, 2009 Share Posted August 26, 2009 looks almost like a tail impression. Link to comment Share on other sites More sharing options...
Traviscounty Posted August 26, 2009 Share Posted August 26, 2009 looks almost like a tail impression. It kinda does look like he got some tail. Link to comment Share on other sites More sharing options...
FossilDAWG Posted August 26, 2009 Share Posted August 26, 2009 This fossil is still puzzling me. Any ideas?This was found in Geneva Pass in SE Idaho at a road cut on Highway 89 through a giant shale bed. According to a geologist's report I was looking at, this is a “Jurassic Twin Creek Limestone (cleaved, locally gypsiferous or fossiliferous, and generally fine-grained), and green shale … and contains calcareous shale with wind ripples, mudcracks and rip-up clasts, plus abundant trace fossils, all representing a periodically exposed west-facing Jurassic carbonate margin” (Fortsch & Link: 289). I've tried a couple different angles hoping the shadows will show up. The third image has some highlighting of one of the most interesting outlines, IMO. Thanks Dave It looks like an impression of a bit of a whorl of a Cardioceras ammonite. Not a real high confidence ID though. I think Cardioceras is known from that formation, certainly it occurs in the Jurassic in Idaho, British Columbia, and Alaska (actually, worldwide in the Oxfordian stage).Don Link to comment Share on other sites More sharing options...
Shamalama Posted August 26, 2009 Share Posted August 26, 2009 I think that your description answered your question. Those look like wind ripples to me. -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...
Auspex Posted August 26, 2009 Share Posted August 26, 2009 I think imprint (ammonite?), rather than trackway. The width, depth, and regularity of the impression is not so track-like. "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...
ebrocklds Posted August 26, 2009 Share Posted August 26, 2009 I think that your description answered your question. Those look like wind ripples to me. i agree ^ they appear to be a shallow water ripple that has been mostly covered over with another layer of fine grained sediment. if you look closely at them you will notice that they are not symetrical (i am looking at each small peak) that indicates directional flow. typically trackways are left in a draging pattern or a distinct foot print. it is less likely that a taill or other body part would have layed in the sediment then lifted straight out to leave such a nice clean impression. (this has been seen it is just much less likely) just my opinion take it for what it is worth Brock Link to comment Share on other sites More sharing options...
Auspex Posted August 26, 2009 Share Posted August 26, 2009 There are a number of features that are consistent with ripple marks; I am not used to seeing the edges of such go "uphill", lateral to the indicated direction of flow, though. "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...
fig rocks Posted August 26, 2009 Share Posted August 26, 2009 Well, it's a cool imprint whatever it is. Link to comment Share on other sites More sharing options...
Shamalama Posted August 27, 2009 Share Posted August 27, 2009 There are a number of features that are consistent with ripple marks; I am not used to seeing the edges of such go "uphill", lateral to the indicated direction of flow, though. Could that be because these are not water formed, but rather by wind and therefore have less dense of a medium sculpting them? I realize that both wind and water ripples look very similar but mayhaps the mud had a certain consistency that the wind was able to push juuuuust right? I'm getting too far out on the branch here... better head back in before I fall in and make my own ripple marks. -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...
tracer Posted August 27, 2009 Share Posted August 27, 2009 when ya'll start with the aero- and hydrodynamic equations, i'm setting the topic to wavily invisible. Link to comment Share on other sites More sharing options...
danielp Posted August 27, 2009 Share Posted August 27, 2009 Looks like a partial ammonite impression to me. Link to comment Share on other sites More sharing options...
Terry Dactyll Posted August 27, 2009 Share Posted August 27, 2009 Its too much of a definable edge and shape for wind ripples or water ripples...Id go with ammonite impression to.... Cheers Steve... And Welcome if your a New Member... Link to comment Share on other sites More sharing options...
Ammonoid Posted August 27, 2009 Share Posted August 27, 2009 The Twin Creek Limestone is Bajocian to Callovian in age. Ammonites are common in the lower (Bajocian) portion and rare in the upper (Bathonian and Callovian) parts. Your fossil looks like an impression of Stemmatoceras or Spiroceras, but I wouldnt rule out wind ripple. Kevin Link to comment Share on other sites More sharing options...
davehunt Posted August 28, 2009 Author Share Posted August 28, 2009 Thanks everyone for your comments (both funny and educated). I think this one will stay in the "still interesting" pile for a while. My gut said take an Occam's Razor approach and stick with wind ripples, but the curve of the impression made me look for a second opinion. Ammonoid, are you the author of this site: www.ammonoid.com ? Great site, highly recommended to our community. Link to comment Share on other sites More sharing options...
tracer Posted August 28, 2009 Share Posted August 28, 2009 i would bet any amount of money that that thing ain't even remotely related to ammonoidality in concept or implementation. course, that's a safe bet for me because i don't have any amount of money. <calling off monitor> "tj! can i borrow some money to make a bet on the forum?!" he said "no". Link to comment Share on other sites More sharing options...
jeepinthemud Posted August 28, 2009 Share Posted August 28, 2009 I would go with ripple marks. I would say underwater, but in a faster paced setting... perhaps as the water was flooding inland, and covered the mud (and the sharply defined crests) with sediments because it was flooding! "To do is to be." -Socrates "People are Stupid." -Wizard's First Rule "Happiness is a warm Jeep." -Auspex Link to comment Share on other sites More sharing options...
Auspex Posted August 28, 2009 Share Posted August 28, 2009 Somehow it just came to me: Jeep tracks! "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...
fig rocks Posted August 28, 2009 Share Posted August 28, 2009 Somehow it just came to me: Jeep tracks! I think with all the rain they're getting in Texas jeep should change his name to jeepinthedirt. Link to comment Share on other sites More sharing options...
Ammonoid Posted August 28, 2009 Share Posted August 28, 2009 Ammonoid, are you the author of this site: www.ammonoid.com ?Great site, highly recommended to our community. Guilty Kevin Link to comment Share on other sites More sharing options...
jeepinthemud Posted August 28, 2009 Share Posted August 28, 2009 Somehow it just came to me: Jeep tracks! ....well, with all the fossils of mini-Jeeps and their drivers, this might be a valid conclusion! I think with all the rain they're getting in Texas jeep should change his name to jeepinthedirt. I had a VERY good laugh at that! and yeah, currently its not Jeepinthemud... but Jeepinthesand.. (yay beaches!) "To do is to be." -Socrates "People are Stupid." -Wizard's First Rule "Happiness is a warm Jeep." -Auspex Link to comment Share on other sites More sharing options...
Auspex Posted August 28, 2009 Share Posted August 28, 2009 Just for general comparison: "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...
tracer Posted August 28, 2009 Share Posted August 28, 2009 auspex - while the board's down, please study the below-linked information, particularlys section II, the "mathematical model", and we'll then discuss this on the other side of the cutover, presuming his gatorness can bring us back from the doubtless rippled abyss. say what? Link to comment Share on other sites More sharing options...
Ammonoid Posted August 29, 2009 Share Posted August 29, 2009 particularlys section II, the "mathematical model", Fantastic reading Kevin Link to comment Share on other sites More sharing options...
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