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While I am out in the badlands of the San Juan Basin, I keep an eye out for the trace fossil known as Asthenopodichnium...lozenge shaped overlapping pouches or cavities found in petrified wood. My first encounter with it was a number of years ago in an outcrop of Upper Cretaceous Menefee Formation. I threw a chunk of wood, with this very interesting texture, in my bag and took it home. Perplexed by what it might be, I showed it to Spencer Lucas at the New Mexico Museum of Natural History. He was happy to see this specimen and we discussed the theories of what it might represent, as it is not fully understood. We wrote up a small abstract with a few other co-authors for a Geologic Society meeting and since then, I have looked for other specimens while wandering. 


In 2015, some specimens found in the Upper Cretaceous Kirtland Formation of the San Juan Basin were published in the NMMNHS' Bulletin 67 and are the first published record of these trace fossils in the Kirtland. The following is a link to that paper.


The trace fossil Asthenopodichnium from the Upper Cretaceous of the San Juan Basin, New Mexico


On a recent adventure, with @Opuntia, in the Kirtland Formation of the San Juan Basin I stumbled upon these...
















...and was delighted. I couldn't wait, and texted the photos to Spencer. His response was "collect it!" In later conversations he asked where the specimens were and we discussed their location, a potential small paper and started planning a return trip to document them. Excited, I sat pondering the fossils and referred back to the paper. As I looked at the field photo in the paper I noticed a rock in the frame...I had seen that rock. I compared my field photos to the publication's and realized that I was looking at the same locality. 


Publication field photo:



PFOOLEY's field photo:



This left me feeling a bit deflated as there would be no need for collection nor a small paper. I began to think  back to the time, all those years ago, when I first encountered this trace fossil in the Menefee...I'm going back there and can hopefully relocate that site...might just have a small paper in store after all.


I post this here to see if any of you have seen this trace or maybe just some thoughts on this fascinating fossil. 


Got Asthenopodichnium?



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While it is a bit of a bummer that it has already been written up, how cool is it that you found the same exact piece!

That is pretty awesome, in my book!  Congrats. I hope your other potential locality works out.

Keep moving forward, friend.  :)


EDIT: By the way, I also find this trace fossil very interesting.

Assuming it is some sort of insect trace fossil, a la Emerald Ash Borer type activity.

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Looks like a good part of it has eroded and is gone. Perhaps one should collect it before it all disappears?

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I too have not seen this. But I too think it is impressive that you found the same piece without looking. What are the odds?!


That is an interesting trace

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