minnbuckeye Posted October 1, 2016 Share Posted October 1, 2016 In the driftless areas of Minnesota, Iowa, and Wisconsin I find many Orthocone Cephalopods. Each one seems to have its unique way of being preserved, some as an outer shell, others with their internal anatomy showing. A few weeks ago Raggedy Man posted a cephalopod that looked to be a siphuncle to me. Bev on the otherhand thought it was a phragmocone. No experts chimed in so a conclusion was not determined. That following weekend, I did a little collecting in Iowa. The trip was highlighted with the finding of many cephalopods. As I cleaned the findings, my mind went back to Raggedy Man's post. The more I looked at these collections, the more I wanted to understand the anatomy exposed. I think my biggest frustrations are telling siphuncles from phragmocones. Are siphuncles always smooth surfaced? Should septa be seen in any unworn phragmacone? How does one differentiate phragmacone from the external surface of a cephalopod? Finally does anyone have a good site that ID's our local Ordovician cephalopods? Thanks for any input!!!!! Now enjoy my finds. By the way, since it IS football season, I HAD to use a BUCKEYE to size my cephalopods. If anyone is unfamiliar with a buckeye, it is a little bigger than an acorn. For any of you buckeyes, OH...... Link to comment Share on other sites More sharing options...
minnbuckeye Posted October 1, 2016 Author Share Posted October 1, 2016 Link to comment Share on other sites More sharing options...
minnbuckeye Posted October 1, 2016 Author Share Posted October 1, 2016 Link to comment Share on other sites More sharing options...
minnbuckeye Posted October 1, 2016 Author Share Posted October 1, 2016 Link to comment Share on other sites More sharing options...
minnbuckeye Posted October 1, 2016 Author Share Posted October 1, 2016 Link to comment Share on other sites More sharing options...
minnbuckeye Posted October 1, 2016 Author Share Posted October 1, 2016 Link to comment Share on other sites More sharing options...
Fossildude19 Posted October 1, 2016 Share Posted October 1, 2016 This is the best diagram of cephalopod anatomy I have come across. I can't help much beyond that, ... and some of your items sure look confusing to me, as well. Here's hoping someone can chime in with more observations about your pieces. 3 Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 __________________________________________________ "In every walk with nature one receives far more than he seeks." John Muir ~ ~ ~ ~ ><))))( *> About Me Link to comment Share on other sites More sharing options...
minnbuckeye Posted October 1, 2016 Author Share Posted October 1, 2016 Link to comment Share on other sites More sharing options...
minnbuckeye Posted October 1, 2016 Author Share Posted October 1, 2016 Notice the patch of bryozoan attached to this specimen Link to comment Share on other sites More sharing options...
fossiling Posted October 1, 2016 Share Posted October 1, 2016 what is that object you used for size comparison? A nut or something? Keep looking! They're everywhere! Link to comment Share on other sites More sharing options...
tmaier Posted October 1, 2016 Share Posted October 1, 2016 A buckeye, which is a nut off the tree of a Hazel tree. They are about 25 mm diameter (an inch). 2 Link to comment Share on other sites More sharing options...
fossiling Posted October 1, 2016 Share Posted October 1, 2016 thanks! paleoCOOL! Keep looking! They're everywhere! Link to comment Share on other sites More sharing options...
Goatcabin15 Posted October 1, 2016 Share Posted October 1, 2016 orhocerus this fossil is found in the ordovician rock .. here in cornwall they are found in devoniian layers they also occur in the silurian levels in shropshire and wales Link to comment Share on other sites More sharing options...
tmaier Posted October 1, 2016 Share Posted October 1, 2016 A really nice collection, Minnbuckeye. I've collected in the Ordovician of southern Minnesota, and found some interesting stuff. You have a pretty good anatomy lesson on cephalopods there. Link to comment Share on other sites More sharing options...
abyssunder Posted October 1, 2016 Share Posted October 1, 2016 I think that the one in the last picture is an orthoconic cephalopod siphuncle steinkern with part of the remnant phragmocone at one end (right side of the picture). 1 " We are not separate and independent entities, but like links in a chain, and we could not by any means be what we are without those who went before us and showed us the way. " Thomas Mann My Library Link to comment Share on other sites More sharing options...
Raggedy Man Posted October 1, 2016 Share Posted October 1, 2016 51 minutes ago, minnbuckeye said: That a sweet piece Minnbuckeye! ...I'm back. Link to comment Share on other sites More sharing options...
doushantuo Posted October 1, 2016 Share Posted October 1, 2016 I hope SOMEONE finds this useful http://palaeo-electronica.org/2001_2/compact/compact.pdf Link to comment Share on other sites More sharing options...
Rob Russell Posted October 1, 2016 Share Posted October 1, 2016 The one pictured in the bottom right hand corner of the group photo, which I believe is pictured individually first, may be endoceras. 1 Finding my way through life; one fossil at a time. Link to comment Share on other sites More sharing options...
FossilDAWG Posted October 1, 2016 Share Posted October 1, 2016 50 minutes ago, minnbuckeye said: These are examples of siphuncles of an endocerid nautiloid, possibly Endoceras. What appear to be "sutures" on the outside are connecting rings where the septa met the siphuncle. Kind of the reverse of suture lines, which formed where the septa met the outside shell. Note that there is no siphuncle-like round structure visible in the end-on view. This is a strong indication that you are looking at a siphuncle, though not foolproof. Also the connecting rings tend to make a more inclined angle with the siphuncle, compared to the sutures, although again this is not always the case. Don 2 Link to comment Share on other sites More sharing options...
FossilDAWG Posted October 1, 2016 Share Posted October 1, 2016 2 hours ago, minnbuckeye said: Here you can clearly see the siphuncle in the end-on view, still encased in the camerae (chambers formed by the septa). The side view shows camerae and suture lines, the exterior of the shell has dissolved away. Again, likely an endocerid. Don 2 Link to comment Share on other sites More sharing options...
FossilDAWG Posted October 1, 2016 Share Posted October 1, 2016 2 hours ago, minnbuckeye said: In this specimen, the spike-like part is the siphuncle, and the ball on the end is a few remaining camerae. The bryozoan growing on the siphuncle indicates a complicated taphonomic history: 1. The nautiloid died, was buried in the sediment, sediment filled the siphuncle and at least some of the camerae, and hardened (lithified) enough to keep the shape of the structures. The curved mark on the siphuncle may have been made by some animal burrowing into the sediment. 2. The specimen was unburied, and eroded enough to expose the siphuncle, or perhaps the camerae at the end never filled with sediment. 3. The bryozoan grew on the exposed siphuncle, which was a hard substrate suitable for attachment. The fossil must have been exposed for some time for the bryozoan to reach this size. 4. The fossil was reburied, and the enclosing sediment lithified to shale or limestone. 5. 400+ million years later erosion again exposed the fossil for you to find it. Don 2 Link to comment Share on other sites More sharing options...
CBOB Posted October 1, 2016 Share Posted October 1, 2016 Wow! Really great finds! Thanks for sharing. The "spike like" ceph is really an interesting one. Link to comment Share on other sites More sharing options...
Fossildude19 Posted October 2, 2016 Share Posted October 2, 2016 19 hours ago, FossilDAWG said: These are examples of siphuncles of an endocerid nautiloid, possibly Endoceras. What appear to be "sutures" on the outside are connecting rings where the septa met the siphuncle. Kind of the reverse of suture lines, which formed where the septa met the outside shell. Note that there is no siphuncle-like round structure visible in the end-on view. This is a strong indication that you are looking at a siphuncle, though not foolproof. Also the connecting rings tend to make a more inclined angle with the siphuncle, compared to the sutures, although again this is not always the case. Don Thanks Don, for the cogent explanation of "what is what" with Minnbuckeye's cephalopod fossils. Fantastic job - I have learned a few things today. Thanks again. Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 __________________________________________________ "In every walk with nature one receives far more than he seeks." John Muir ~ ~ ~ ~ ><))))( *> About Me Link to comment Share on other sites More sharing options...
minnbuckeye Posted October 2, 2016 Author Share Posted October 2, 2016 Thanks to all that have tried to educate me further!!!! To sum up what I think is correct: 1. The shells of the orthocone cephalopods are eroded away. So the ridges seen on my specimens is actually a mold of the inner chambered part of the phragmocone, not the surface of the cephalopod. 2. Siphuncles are not smooth (assuming no erosional forces) but show evidence of the suture pattern. Again , they represent an infill of sediment in a hollow tube so an impression of the suture pattern occurs. Link to comment Share on other sites More sharing options...
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