RCFossils Posted March 20, 2017 Share Posted March 20, 2017 Hello Fossil Forum friends. It has been quite a while since I posted on the forum and decided to share a find that I recently collected. This specimen was found March 1st 2017 and after three freeze thaw cycles split open last week. Unfortunately the other half shattered into several pieces. I already know what the fossil is and thought it would be a fun challenge for forum members to test out their Mazon Creek identification skills. When I first glanced at it, I thought it was a bit of plant material and almost disgarded it. I will give one hint and state that it is an animal and was collected at Pit 11 which preserves many unusual marine fossils. The concretion measures approximately 2" across. I look forward to hearing members opinions. Link to comment Share on other sites More sharing options...
RCFossils Posted March 20, 2017 Author Share Posted March 20, 2017 Link to comment Share on other sites More sharing options...
RCFossils Posted March 20, 2017 Author Share Posted March 20, 2017 Link to comment Share on other sites More sharing options...
Fossildude19 Posted March 20, 2017 Share Posted March 20, 2017 This looks like a Thylacocephalan arthropod - not sure what species, although Concavicaris georgeorum has been mentioned from the Mazon area. Fantastic fossil, Rob! Regards, Image from linked PDF below: PDF 5 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...
fossilized6s Posted March 20, 2017 Share Posted March 20, 2017 That thing is killer, Rob! ~Charlie~ "There are those that look at things the way they are, and ask why.....i dream of things that never were, and ask why not?" ~RFK ->Get your Mosasaur print ->How to spot a fake Trilobite ->How to identify a CONCRETION from a DINOSAUR EGG Link to comment Share on other sites More sharing options...
doushantuo Posted March 20, 2017 Share Posted March 20, 2017 Tim is right,Thylacocephalan. Link to comment Share on other sites More sharing options...
doushantuo Posted March 20, 2017 Share Posted March 20, 2017 thyl Link to comment Share on other sites More sharing options...
digit Posted March 20, 2017 Share Posted March 20, 2017 Pretty sweet find! Thanks for showing a rarity like this. Cheers. -Ken Link to comment Share on other sites More sharing options...
snolly50 Posted March 20, 2017 Share Posted March 20, 2017 @doushantuo Thanks for posting the pdf. I could not get my mind around what this critter looked like! The line drawing representation in the article was very helpful. Human beings, who are almost unique in having the ability to learn from the experience of others, also are remarkable for their apparent disinclination to do so. - Douglas Adams, Last Chance to See Link to comment Share on other sites More sharing options...
RCFossils Posted March 20, 2017 Author Share Posted March 20, 2017 Well done everyone! This is easily one of the most bizarre animals that can be found in the Mazon Creek deposit. There are 2 described species of Thylacocephala from the Essex portion of the deposit The smaller and more common type is Concavicaris georgeorum. This is an example of the rarer Convexicaris mazonensis. I have collected around a dozen of these 2 types over the years. This is by far the best example. The appendages are normally not preserved or just partials. This example shows the incredible size of the appendages in relation to the body size. You can also clearly see the enormous eye. Here is a reconstruction of Convexicaris. 3 Link to comment Share on other sites More sharing options...
Fossildude19 Posted March 20, 2017 Share Posted March 20, 2017 1 minute ago, RCFossils said: Well done everyone! This is easily one of the most bizarre animals that can be found in the Mazon Creek deposit. There are 2 described species of Thylacocephala from the Essex portion of the deposit The smaller and more common type is Concavicaris georgeorum. This is an example of the rarer Convexicaris mazonensis. I have collected around a dozen of these 2 types over the years. This is by far the best example. The appendages are normally not preserved or just partials. This example shows the incredible size of the appendages in relation to the body size. You can also clearly see the enormous eye. Here is a reconstruction of Convexicaris. Thanks for posting this gem, Rob. I had actually just happened upon a picture of these somewhere, just a week or two ago, and downloaded the paper I found. Otherwise, I would not have known what this was. Can we see some more examples of these critters? 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...
Rob Russell Posted March 20, 2017 Share Posted March 20, 2017 Fabulous find, Rob! Congrats! Finding my way through life; one fossil at a time. Link to comment Share on other sites More sharing options...
RCFossils Posted March 23, 2017 Author Share Posted March 23, 2017 Here are a few additional specimens of Convexicaris 1 Link to comment Share on other sites More sharing options...
RCFossils Posted March 23, 2017 Author Share Posted March 23, 2017 1 Link to comment Share on other sites More sharing options...
RCFossils Posted March 23, 2017 Author Share Posted March 23, 2017 Here is a picture of the more common Mazon Creek Thylacocephala. Concavicaris georgeorum 1 Link to comment Share on other sites More sharing options...
RCFossils Posted March 23, 2017 Author Share Posted March 23, 2017 Here Is another Concavicaris georgeorum 1 Link to comment Share on other sites More sharing options...
RCFossils Posted March 23, 2017 Author Share Posted March 23, 2017 I collected this little guy a few years back. Not sure if it is one of the described types. It is the smallest that I have seen. 1 Link to comment Share on other sites More sharing options...
RCFossils Posted March 23, 2017 Author Share Posted March 23, 2017 This last example is not considered part of the Mazon Creek deposit but it occurs in a black shale above. In Indiana this would be considered the Mecca Quarry Shale. This is Concavicaris sinuata. I believe this is the largest described Thylacocephala. I have collected examples almost double this size. 1 Link to comment Share on other sites More sharing options...
Fossildude19 Posted March 23, 2017 Share Posted March 23, 2017 Rob, Thank you for posting these extra examples. These were fascinating creatures - I enjoyed seeing these all. Your collection is quite amazing. Regards, 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...
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