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sTamprockcoin

Possible track

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sTamprockcoin

Just picked this and a similar one up this morning. This is a Devonian , Brallier/Harrell formation, raod cut a few blocks from my house.

Is this a preserved track and (I know its indistinct) and if so from what kind of critter?

Any help is appreciated.

31717a.jpg

31717b.jpg

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Fossildude19

Nice find, Tim! :) 

 

I agree,  - similar ones found in this flickr album.

Regards, 

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westcoast

While the similarities are obvious it seems a little odd that a  long brittle star arm can produce such a neat trace if it was crawling? Also just to poke at this a bit more, the arm doesn't appear to taper like most brittle stars. I haven't read any of the relevant  literature which interprets this ichnofossil so I'm just throwing it out there, maybe there are some modern comparitive studies? 

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ynot

If You watch brittle star videos thier movement is by flailing thier arms. It is a unique form of locomotion. I co not see how that type of movement could leave a continuous track.

Also - where are the marks left by the other arms of a brittle star?

http://www.livescience.com/20196-brittle-star-movement.html

http://www.bing.com/videos/search?q=brittle+star+movement&qpvt=brittlestar+movement&FORM=VDRE

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westcoast

I'm thinking something along the lines of the makers of Gyrochorte or a straighter type of Nereites biserialis.  There is  no consensus as to the makers of those traces but nobody suggests ophiuroid. Ichnology really is the Dark Arts of paleontology however.

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Fossildude19
10 hours ago, ynot said:

If You watch brittle star videos thier movement is by flailing thier arms. It is a unique form of locomotion. I co not see how that type of movement could leave a continuous track.

Also - where are the marks left by the other arms of a brittle star?

http://www.livescience.com/20196-brittle-star-movement.html

http://www.bing.com/videos/search?q=brittle+star+movement&qpvt=brittlestar+movement&FORM=VDRE

 

The paper that sTamprockcoin posted suggests how the trace could have been made, but, in my opinion,... is far from the last word on the subject. 

 

"As pointed out by one of the paper’s reviewers (Philip Novack-Gottshall, personal communication, 2006), if P. biseriatus is the product of an ophiuroid or an asterozoan, the lack of pentameral symmetry in the impressions of arms, especially in association with possible feeding marks, seems contradictory. We would offer the observation that intact bedding surfaces containing multiple P. biseriatus are commonly marked by very small (less than 1 cm. in height), broad ripples. The irregular topography of this sediment surface may have precluded the preservation of the imprints of all five arms.

Alternatively, as illustrated and discussed by Schäfer (1972, Figure 117, p. 210), the typical mode of ophiuroid movement is by single-arm locomotion where one arm propels the organism (see Figure 6) and the remaining arms trail behind. This may help explain the predominance of single P. biseriatus even in conjunction with mouth impressions, especially if the tracemaker was feeding opportunistically as it moved across the bottom ."

 

I agree that the fossil is Pteridichnites biseriatus, but am skeptical of the trace maker's identity.

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westcoast

I agree that Pteridichnites biseriatus is the correct name for this trace but the maker is questionable

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sTamprockcoin

Thanks for the variety of discussion. I thought that this uncertainty might be the case. I'm pleased to know the name and quality of what I've found. I'm  definitely going to do more exploring at the spot and who knows maybe I'll make a contribution to the bottom feeders (pun on trace fossils) of paleontology.:trilowalk:

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abyssunder
On 3/18/2017 at 12:35 AM, westcoast said:

I haven't read any of the relevant  literature which interprets this ichnofossil so I'm just throwing it out there, maybe there are some modern comparitive studies? 

 

On 3/18/2017 at 4:05 PM, sTamprockcoin said:

I'm pleased to know the name and quality of what I've found.

 

I find this older topic related to Pteridichnites biseriatus.
According to Miller et al., 2009, Pteridichnites biseriatus is now considered Psammichnites biseriatus.

 

" The specimens from the Saltville area suggest that Psammichnites biseriatus was produced by a small, shallow-burrowing, mollusc- or annelid-like deposit feeder, that thrived in the upper parts of recently deposited muddy turbidites in a depositional basin that supported few other kinds of benthic organisms, owing to frequent erosion-deposition events, continual turbidity and influx of freshwater from Catskill deltaic lobes to the east, and possibly because of intervals/zones of stagnation and eutrophication at the seafloor. "

 

 

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