FossilDAWG Posted January 15, 2015 Share Posted January 15, 2015 I agree it would be great to see the "in situ" photos. Also I wonder if it would be possible to identify this specimen to species. If it is a Moroccan species that would establish that the specimen was placed where it was found relatively recently. For example, someone may have thought it funny to "mess with" some collector, cementing an obviously out-of-place fossil where their intended victim might find it, except cds7189 got to it first. On the other hand it might be an indigenous American species, which could have originated from Devonian rocks not too far away (the neighboring county). It seems to me that the specimen seems eroded or etched all over: large pieces of the shell are missing, leaving an internal mold, and the large size of the pores on the remaining shell suggests to me that it has been etched or weathered. If it was in place in Cretaceous strata it could be an erratic or mechanically transported. Did this come out of a conglomerate bed? Are there other pebbles present in the layer it came from? More interesting is the possibility it could have been a gastrolith, and was abraded/etched while passing through the gut of some marine reptile. Don Link to comment Share on other sites More sharing options...
Uncle Siphuncle Posted January 15, 2015 Share Posted January 15, 2015 (edited) Devonian strata are 100 miles from Austin and have a very narrow outcrop area in the Hill Country. In fact, if memory serves, Devonian exposures are mapped undivided with equally sparse Mississippian strata. Had a trilobite washed out and been redeposited during Cretaceous or Holocene times, it would resemble a pebble more so than a trilobite after covering the distance. If an erratic boulder was transported somehow, sometime and provided a billion to one chance of an extractable trilobite in Round Rock, if there is original matrix remaining where you dug it out, I would surmise that a study of microfossils in the surrounding matrix would support or refute the claim. Edited January 15, 2015 by Uncle Siphuncle Grüße, Daniel A. Wöhr aus Südtexas "To the motivated go the spoils." Link to comment Share on other sites More sharing options...
JustPlainPetrified Posted January 15, 2015 Share Posted January 15, 2015 I was looking at the defensive adaptation of enrollment displayed by this specimen. Considering it rolled and locked itself into a ball, I don't find it outside the realm of possibility that it was dislodged at some geologic point after becoming fossilized and was re-deposited into the more recent matrix. Why isn't that possible? Isn't that what sandstone is anyway? Trilobite enrollment and coaptative structures.html Link to comment Share on other sites More sharing options...
Uncle Siphuncle Posted January 15, 2015 Share Posted January 15, 2015 I've seen fossils of all ages hold up poorly to being transported by modern flood events. Some don't hold up well after moving 100 yards. This one somehow moved 100 miles, if it is indeed from Texas. Again, a study of micros and lithologic composition of surrounding rock would tell if it is even from Texas. Grüße, Daniel A. Wöhr aus Südtexas "To the motivated go the spoils." Link to comment Share on other sites More sharing options...
JohnJ Posted January 15, 2015 Share Posted January 15, 2015 Again, this is not an area of Texas with a wide range of redeposited geologic strata. There are no exposed Paleozoic strata in this watershed—which means that a naturally occurring rock with a trilobite did not come from 'upstream' anywhere. Finding a naturally occurring trilobite in the Upper Cretaceous Austin Chalk, Eagle Ford, or Buda Formation (or any rocks from further upstream where the strata transition to, at the oldest, the Lower Cretaceous Fredericksburg Group) is akin to finding a meg tooth buried in a crack in the granite on Mt. Rushmore. It didn't get there as a result of geologic events. Bedrock geology of the Round Rock area. It's a cool fossil with an unusual story. It would be very useful to see additional images from different angles...then, our trilobite experts could likely narrow down its geologic/geographic origin. 1 The human mind has the ability to believe anything is true. - JJ Link to comment Share on other sites More sharing options...
Uncle Siphuncle Posted January 15, 2015 Share Posted January 15, 2015 Even if transported during the Cretaceous, one would think there would be evidence of additional erratics in Round Rock of similar age. Grüße, Daniel A. Wöhr aus Südtexas "To the motivated go the spoils." Link to comment Share on other sites More sharing options...
JohnJ Posted January 15, 2015 Share Posted January 15, 2015 Even if transported during the Cretaceous, one would think there would be evidence of additional erratics in Round Rock of similar age. Very true...and, as you are well aware, none of the Cretaceous strata in the area are known for a depositional environment that caused dispersion of Paleozoic erratics. The human mind has the ability to believe anything is true. - JJ Link to comment Share on other sites More sharing options...
Uncle Siphuncle Posted January 15, 2015 Share Posted January 15, 2015 That's my understanding as well...hence healthy skepticism in this case. Would somebody please pass the popcorn? Grüße, Daniel A. Wöhr aus Südtexas "To the motivated go the spoils." Link to comment Share on other sites More sharing options...
Plax Posted January 15, 2015 Share Posted January 15, 2015 A root rafted erratic is the only way this could have been transported in my opinion but this thing has prankster written all over it. The odds of root rafting picking up a complete trilobite and not just some cobbles are difficult to comprehend. Link to comment Share on other sites More sharing options...
Herb Posted January 15, 2015 Share Posted January 15, 2015 (edited) it would be nice to see some pix of the bedrock this came from, and shots of ANY other fossils in the matrix. No Devonian trilobites in the Austin area. Edited January 15, 2015 by Herb "Absence of evidence is not evidence of absence"_ Carl Sagen No trees were killed in this posting......however, many innocent electrons were diverted from where they originally intended to go. " I think, therefore I collect fossils." _ Me "When you have eliminated the impossible, whatever remains, however improbable, must be the truth."__S. Holmes "can't we all just get along?" Jack Nicholson from Mars Attacks Link to comment Share on other sites More sharing options...
Cole Posted January 15, 2015 Share Posted January 15, 2015 I found one in 2010 that is between 400 - 500 myo in an area that geologically is only 1 - 3 myo. Here is that thread: http://www.thefossilforum.com/index.php?/topic/16892-is-this-a-trilobite-pseudofossil/ I know you are in a completely different area. Where I live, its understood how this fossil came to be where I found it. Can't wait to see the new pictures. Cole~ Knowledge has three degrees-opinion, science, illumination. The means or instrument of the first is sense; of the second, dialectic; of the third, intuition. Plotinus 204 or 205 C.E., Egyptian Philosopher Link to comment Share on other sites More sharing options...
Uncle Siphuncle Posted January 15, 2015 Share Posted January 15, 2015 I've visited over 1000 Texas exposures in the last 13 years, some many times, and in that time frame I've never seen one fossil out of context, "in situ". If I were a betting man, I'd say the house wins this round. Grüße, Daniel A. Wöhr aus Südtexas "To the motivated go the spoils." Link to comment Share on other sites More sharing options...
jpc Posted January 15, 2015 Share Posted January 15, 2015 you asked a while back if it would be worth showing it to the folks at UT... I think so. Bring along your pix of the site. Link to comment Share on other sites More sharing options...
cds7189 Posted January 16, 2015 Author Share Posted January 16, 2015 I spoke with the folks at UT and they are requesting that I bring the fossil and pictures of the location to them to inspect. I'm posting a picture of a fossil (not the trilobite I found) in the matrix where I found the specimen as requested. I also wanted to say that My wife says she remembers the fossil being in a section of a crack that was very tightly compressed matrix. I will also post a larger picture of the location where I found it with the next post. Link to comment Share on other sites More sharing options...
cds7189 Posted January 16, 2015 Author Share Posted January 16, 2015 Picture of the location. Link to comment Share on other sites More sharing options...
cds7189 Posted January 16, 2015 Author Share Posted January 16, 2015 Different Angles Link to comment Share on other sites More sharing options...
cds7189 Posted January 16, 2015 Author Share Posted January 16, 2015 Different angles Link to comment Share on other sites More sharing options...
cds7189 Posted January 16, 2015 Author Share Posted January 16, 2015 Different Angles Link to comment Share on other sites More sharing options...
cds7189 Posted January 16, 2015 Author Share Posted January 16, 2015 Different angles Link to comment Share on other sites More sharing options...
JimB88 Posted January 16, 2015 Share Posted January 16, 2015 ummm..it doesnt match the matrix (which is lighter.) Link to comment Share on other sites More sharing options...
Cole Posted January 16, 2015 Share Posted January 16, 2015 Pretty awesome. Do you have any pictures of the specimen prior to removing the matrix off of it? Cole~ Knowledge has three degrees-opinion, science, illumination. The means or instrument of the first is sense; of the second, dialectic; of the third, intuition. Plotinus 204 or 205 C.E., Egyptian Philosopher Link to comment Share on other sites More sharing options...
cds7189 Posted January 16, 2015 Author Share Posted January 16, 2015 Different Angles Link to comment Share on other sites More sharing options...
cds7189 Posted January 16, 2015 Author Share Posted January 16, 2015 I can not find any I took before I removed the fossil. I thought I did but may have deleted them. I take a lot of pictures and delete lots as I run out of room. I'm still looking. I literally have hundreds and hundreds and hundreds from as far back as 3 years ago. Still looking!! Link to comment Share on other sites More sharing options...
cds7189 Posted January 16, 2015 Author Share Posted January 16, 2015 Sorry for all the different post but I'm having issues with the picture size. Link to comment Share on other sites More sharing options...
Missourian Posted January 16, 2015 Share Posted January 16, 2015 Does the trilobite still have any of the sandstone matrix remaining (not just the original Devonian matrix)? Context is critical. Link to comment Share on other sites More sharing options...
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