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I went to the local outcrop in my hometown and found this matrix. At first I thought it was broken crinoid segments but after giving it two baths and two good scrubbing with a toothbrush, the details are much clearer and now I doubt it is crinoidal. Perhaps it is Planolite burrows? I think this matrix is of Longford Member, Kiowa formation, Albian. The outcrop I found this matrix at is mostly the Wellington formation, Permian; but it is topped by Kiowa formation and I found it near at the top of this outcrop. I would like to hear your opinions, thanks!

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"Other trace fossils in the capping siltstone include burrows of uncertain affinities. One is a Planolites-like structure (Häntzschel, 1962; Frey and Howard, 1970) that consists of circular molds and casts that both transect and tend to follow the wavy bedding of the rock. The molds and their siltstone casts are about 1 cm in diameter and as much as 10 cm long. A second type of burrow is tubular and subvertical. Some are rod-shaped; others are Y-shaped. They measure from 0.2 to 1.5 cm in diameter and are as much as 20 cm long, although most are less than 15 cm long. Most of the structures are smooth walled and resemble the various rod-shaped and tubular burrows described by Frey and Howard (1970) and Siemers (1971). Some, however, have a segmented appearance similar to that of Arthrophycus (Frey and Howard, 1970), but the segmentation may be an artifact of bedding."

http://www.kgs.ku.edu/Publications/Bulletins/219/03_desc.html

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Could it represent a sea floor where crinoid holdfast elements were preserved as natural casts ?

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10 hours ago, Rockwood said:

Could it represent a sea floor where crinoid holdfast elements were preserved as natural casts ?

I do not know. Kiowa formation is described as mostly brackish, estuary and barrier islands ecosystem. I do not know what all marine habitats crinoid can be found. I spent hours finding the scholar papers and other academic sources on crinoid fossils from Kiowa formation and found none, but a link I posted above is the closest thing I could find and it's described as Planolites-like burrows. 

 

It seems to make sense to me because I have found and seen several crinoid pieces and they all are obvious. Again, I'm not sure and I would like to hear people's opinions on here.

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