Brittle Star trace fossil or Trilobite?

[autismoford 22]

Okay so I found this specimen at the Taughannock Falls in Ithaca New York. I found it at the edge of the gorge which consists of Shale, composed of slit and clay that fell onto lime mud and hardened into rock. I've done some research and it appears to be a Brittle star trace fossil formed by their arm grazing the sand floor. Although, these Brittle Star fish traces are known as "Pteridichnites biseriatus" and they have only been discovered so far in upper Devonian shales out in western and eastern Virginia. I'm not an expert but to my knowledge the Ithaca geological formation is Devonian and was slowly covered by sand. Is it possible that the Brittle Star fish once roamed in the ancient sea now known as "Taughannock falls" today? Because a research team is trying to find this specimen and they are wondering if anyone has discovered it. 

Edit: Im referring to the dotted trackway. check this link out for more information.  http://www.wvgs.wvnet.edu/www/news/Pteridichnites.htm

[autismoford 22]

Full image of shale. The first image was taken closely at the trace fossils. 

 

[ynot 7,240]

There sure is a lot going on in this piece. I see several different types of tracks.

However, none look like the disorganized tracks left by brittlestar movement.

Lets see what @abyssunder thinks.

[autismoford 22]

17 minutes ago, ynot said:

There sure is a lot going on in this piece. I see several different types of tracks.

However, none look like the disorganized tracks left by brittlestar movement.

Lets see what @abyssunder thinks.

http://www.wvgs.wvnet.edu/www/news/Pteridichnites.htm

check this out. It resembles what I found. 

[ynot 7,240]

From a google search for "brittlestar tracks", notice the distinct difference.

I think the assumptions made by the page You linked are wrong. They are not brittlestar tracks in My opinion.

[autismoford 22]

6 minutes ago, ynot said:

From a google search for "brittlestar tracks", notice the distinct difference.

I think the assumptions made by the page You linked are wrong. They are not brittlestar tracks in My opinion.

If they were wrong what trackway could it be from? Because this type of trackway was assumed to be from a brittle star fish according to multiple paleontologists. It is most likely caused by only the arm/tentacle grazing the sea floor opposed to the whole body as you pictured. Very few information is known regarding this type of trackway and it has only been observed in limited locations of Devonian shale in Virginia. 

[ynot 7,240]

5 minutes ago, autismoford said:

Because this type of trackway was assumed to be from a brittle star fish according to multiple paleontologists.

 

From the page You linked....

"This track is thought (by us) to have been produced by a marine organism, most probably a brittle starfish. "

This sounds like a guess to Me. Where is the evidence to back it up?

 

The track they show looks much like tracks that have been attributed to trilobite feeding traces in My opinion.

 

12 minutes ago, autismoford said:

It is most likely caused by only the arm grazing the sea floor opposed to the whole body as you pictured. 

How did You determine this?

What happened to the other arms while this track was being laid down by one arm?

[autismoford 22]

2 minutes ago, ynot said:

From the page You linked....

"This track is thought (by us) to have been produced by a marine organism, most probably a brittle starfish. "

This sounds like a guess to Me. Where is the evidence to back it up?

 

The track they show looks much like tracks that have been attributed to trilobite feeding traces in My opinion.

 

How did You determine this?

What happened to the other arms while this track was being laid down by one arm?

Good point. although, there are multiple of these traces assuming that they are the other arms. I guess in the end we will never know. But this was a prediction as I said.   

[Wrangellian 2,489]

I'm with ynot... your item looks like the one in the link, but I doubt it is brittle star. Looks more like trilobite (Cruziana) or something similar (bilaterally symmetrical).

Nice specimen, whatever it is!

[abyssunder 5,574]

14 hours ago, autismoford said:

14 hours ago, ynot said:

There sure is a lot going on in this piece. I see several different types of tracks.

However, none look like the disorganized tracks left by brittlestar movement.

Lets see what @abyssunder thinks.

http://www.wvgs.wvnet.edu/www/news/Pteridichnites.htm

check this out. It resembles what I found. 

 

Those are very interesting traces. I don't know if you have the same type of traces as in the link provided, or not. Better, close-up images may help to see that.

Pteridichnites biseriatus originally was in incertae sedis, as problematica, when the original authors erected the new genus and species name (Clarke and Swartz, 1913). They described as -

" Imprints consisting of two parallel grooves with raised borders, divided by narrow transverse ridges into shallow, nearly square or slightly rounded pits, which commonly alternate in position. The median ridge dividing the two grooves is not straight but is crenulated by slight inflections directed toward the transverse ridges. Length and width of pits subequal. The impressions usually become faint toward their ends and are often curved.
Width of track about 4 mm., diameter of pits about 2 mm. Tracks are several centimeters long. Similar tracks are abundant in the beds containing the Naples fauna in New York."

 

Later, in R. McDowell et al. 2007. The stratigraphic utility of the trace fossil Pteridichnites biseriatus in the Upper Devonian of eastern West Virginia and Western Virginia, US. Southeastern Geology 44 (4): 191-201, it was considered an ophiuroid trace.

 

 

 

[abyssunder 5,574]

Initially, I thought they might be similar to Protovirgularia, e.g. morphotypes of Gilbert & Domenech, 2008, or the ones from the Paleozoic " Scolicia group".

Further investigations revealed that Pteridichnites is not what it was suggested in McDowell et al., 2007. Pteridichnites biseriatus was reassigned to the ichnogenus Psammichnites, according to Miller et al., 2009. Pteridichnites biseriatus became Psammichnites biseriatus.

 

" One of the only abundant fossils in the Frasnian Brallier Formation of southwestern Virginia, and elsewhere in the central Valley and Ridge Province, is the small trace fossil known as "Pteridichnites" biseriatus. Field geologists have used this distinctive biogenic structure for many years as a guide to the Upper Devonian (and especially the lower, shaly portion of the Brallier) in the region. We can affirm the biostratigraphic potential of this trace; but based on the specimens we studied from the Saltville area, we demonstrate that the ichnotaxonomic assignment, along with interpretations of taxonomie affinity of the tracemaker, constructional morphology of the structure, and paleoecologic implications need to be revised. The previous descriptions and interpretations appear to have focused on the basal part of the trace fossil for the most part. When preserved in full relief, however, it is a more complex structure consisting of (1) the familiar ladder-like ventral floor, (2) a meniscoid backfilled core, and (3) a dorsal roof often having a thin, longitudinal groove. These features justify reassignment to the ichnogenus Psammichnites. 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. "

 

reference: W. Miller et al. 2009. 'Pteridichnites' (=Psammichnites) from the Upper Devonian Brallier Formation of southwestern Virginia, USA; ichnotaxonomic status, constructional morphology, and paleoecology: Southeastern Geology 46(4): 187-199

[abyssunder 5,574]

19 hours ago, autismoford said:

If they were wrong what trackway could it be from? Because this type of trackway was assumed to be from a brittle star fish according to multiple paleontologists. It is most likely caused by only the arm/tentacle grazing the sea floor opposed to the whole body as you pictured. Very few information is known regarding this type of trackway and it has only been observed in limited locations of Devonian shale in Virginia.

Please see above the underlined passage.

[sTamprockcoin 143]

Regarding these "only being found in Virginia"  do you have a sourceor is it an assumption based on a type locality description? I'd have to disagree since I've found them in 2 different Brallier outcrops in Blair County PA. 

 

When I posted a link to the same paper I got a good education on the tentative nature of trace fossil origins. Keep looking, researching, & asking ?s.