First Triassic Fossil - Fin Or Tooth And Bone - Lockatong/passaic - Pa

[hitekmastr]

This is my first official Triassic fossil - a tooth (or fish fin) and some associated (poor quality) tissue/bone pieces found in a late afternoon exploration of some rocky outcroppings in Montgomery County, PA.

Both halves of the impression are included. The impression/cast are very faint and some of the definition is in jeopardy of being lost since the material powdered and flaked off a bit as it dried, and is less defined now than when I first brought it home and took the first images.

Here are some views of the full shale piece and surrounding smooth area with a small skin or tissue fragment at the top:

You can see the smooth area around the fossil "tooth or fin" in the positive and negative halves of the shale - which is medium grey in color and about 20 centimeters long. I chiseled open the shale while I was exploring a steep vertical outcropping. What led me to crack this particular piece of shale was a nearby small assortment of what appeared to be dessicated bones and fragments and the shale color was different from the surrounding red shale. I'm including images here of the "bone fragments" and associated material which appear to be fossilized organic material:

This closeup has some impressions/pockets that may help with identification:

.

Update (Oct 23): There is a growing consensus that this may be a fish fin (or scale) - considering that this appears to be attached to a smooth section, and there is a bit of "skin" at the top left, this interpretation makes sense. I agree that I should remove more substrate to see what else can be revealed.

Thanks to Fossildude19 for providing links to the Triassic Teeth chart and to a few experts I contacted off-line to get their opinion.

The best thing about this find - regardless of the faint impressions, difficult ID and the crumbling possible bone and skin - is that this was found in an area where finds are few and far between, in Triassic sediments that are really scarce in Pennsylvania, because glaciers basically scraped and eroded most of the Triassic and Jurassic geological formations down to older (Ordovician, Devonian, Carboniferous) layers.

I wasn't expecting to find anything and this was revealed just as the sun was going down, using the last half hour of daylight and came from inspecting an anomalous shale color in the formation. This suggests that it is worth our time to check out more Triassic formations in our home county/southeastern Pennsylvania. We are totally "clueless" about Triassic fossils (more comfortable with Carboniferous ferns) but since the Passaic and Lockatong formations are scattered in several places within 20 minutes of our home, we are making a few short trips to see what we might run across.

Nancy and I remain interested primarily in Devonian and Carboniferous fossils and sites, however our first venture into Triassic territory holds some promise.

Edited October 23, 2012 by hitekmastr

[Fossildude19]

Michael,

Have been looking at this whatsit for a while now. I had found this site a while back.

" H." in the diagram looks spot on shapewise.But oddly, I do not see H listed - not sure if it is a typo. I'm not sure about size wise - yours looks tiny.

Maybe metoposaur???

I'm thinking you need to contact someone with more knowledge - perhaps Paul Olsen might be able to tell you one way or another.

Also perhaps contacting the guys from this website?

Cool find - whatever it may be - the Triassic is interesting.

Regards,

[hitekmastr]

I agree that the tooth may be H in the referenced paper- there is a small tissue or skin fragment above it which shows up in the last image in the second row. Also, I edited the original post to include the smooth area around the tooth and also included the "bone fragments" that originally caught my attention and caused me to crack everything that was close or associated with these fragments. The "bones" look like they were fossilized after they rotted a bit, or were eroded into this condition. Not much to go on assuming these are bones but the tooth and impression seems clear enough to confirm that this is a "Triassic tooth." I'm happy to get off to a good start with this first Triassic fossil...can't wait to get Nancy involved so we can use her incredibly keen eye to see what else is out there!

In terms of location, we have been exploring several Lockatong formations in Montgomery County, PA, just a few hours at a time to get familiar with the formations and try to identify the most promising spots to explore. There is so much shale and the fossil concentrations or finds are reported to be sparse, the Montgomery County fossils on the Internet suggest there are some cool fossils to discover but many of the samples are fragments, tracks and bone pieces which suggests that this task will be somewhat tedious and take many hours of failure to find something worthwhile.

There is a lot of barren red mudstone punctuated with grey and green shales - I've been studying the layers and formations to zone in on where the fossils might be - not easy considering that I'm doing this by sight and instinct and not much of a geologist but the layers, colors and consistencies do give some clues, I'm finding.

[Fossildude19]

Michael,

I'm not sure that what you are refering to as "bone" is actually bone.

One of the things I've found in fossil hunting the Newark Supergroup is that geology is weird.

The specimens you've posted of bone do not look like bone to my eye, at least from the pics provided.

The better pics of your "Tooth" have me re-thinking the tooth avenue on your first item.

With the better pics, I'm thinking fish scale, or plant. The carbonaceous film on top of the item is indicative of either of those two things.

It vaguely resembles a scale of Diplurus newarki, but, I think you would need to uncover a bit more of it to be sure.

When I find plants in the Shuttle meadow fm, here in CT. I usually find carbonaceous films over the imprints of the plants themselves.

Interested to see if you can uncover a bit more of it.

Regards,

Edited October 22, 2012 by Fossildude19

[phytosaur]

If this was a lockatong formation fossil, i would doubt that it is a tooth. It looks a ton like the base of the jaw section of a paleoniscoid fish. Turseodus and diplurus are probably the most common fish, and vertebrate fossil in the lockatong formation. and in my experience, the jaw is the element that is most often preserved besides scales. disarticulate elements of these fish are pretty common in deep lake siltstones of the lockatong. The bones of these fish almost always have the flakey carbonate film over them. It easily could be another element of the fish, like a scale (there is great variation in scales on a single fish), or some other bone. It could also be plant material, or an ostracod. the specimen doesnt look complete enough to tell exactly what it is.

You should try to expose more of the fossil by carefully using a dental pick. I suspect it will be some fishy element.

As for the "bone" it looks like the mineralization and staining that occurs during diagenesis and weathering of many lockatong rocks, not bone.

-Ben

[hitekmastr]

Terrific analysis - as I said, we're pretty clueless when it comes to Triassic fossils, but there are about a dozen small outcroppings and cuts or RR tunnel exposures near our home so with cold weather approaching we're beginning to make short trips to these sites. Everyone's comments have been VERY enlightening! I'll do a bit more prep and see what other clues are revealed. Thanks for taking the time to examine our first Triassic fossil...much appreciated! (By the way, I should mention that Nancy thought this might be a fin of some sort, almost from the beginning...).

[Fossildude19]

Michael,

It's good that you are keeping an open mind on this. I realize that this is hard to do sometimes.

I wouldn't think fish fin at all, just because the fish of this era had many rays/raylets to their fins.

Look at some of the fish in my gallery.

Skull element or scale is what I would go with, or as mentioned, it could be plant material.

More matrix removal to get an accurate idea of shape and size is advisable to be able to narrow down an ID.

Keep us posted.

Regards,

[hitekmastr]

Based on your collective input, I did a bit more research and found this photo of a Turseodus fossil showing the bottom fins (arrows) (Schaeffer, 1952)...they resemble my fossil. If this is a fin, it would explain the extremely fragile nature of the fossil, which I mentioned in my original post.

Hopefully more prep will reveal more clues.

I also looked at Diplurus but the fins didn't seem to match as closely - they seem to have more distinct and longer ridges in the fins.

[Fossildude19]

Michael,

Here is a reconstruction of Turseodus from THIS PDF.

As you can see - this shows many rays and raylets that make up the fins.

Your specimen is tiny and smooth in a large area. It also appears to be ovoid or elliptical in shape.

This more closely resembles the bones at the base of the jaw as Ben pointed out.

Hope this helps.

Regards,

Edited October 24, 2012 by Fossildude19

[hitekmastr]

I took a second look at my Lockatong fish jaw and scale - which seems to be the consensus for what this is - and on that assumption, inspected the shale sample more closely and although it is very thin already, I was able to chip a few fragments and revealed what appears to be another scale similar in configuration to the first one in my original post. Also there is another small piece that looks a bit similar but not as well defined - these are indicated by the arrows. They are very small but are consistent in size with the original fossil. I'll keep looking and see if there are more on the sample. These have been very tightly compressed, very small, and the impressions are faint and not easy to see. Here is the image:

Edited February 15, 2013 by hitekmastr

[hitekmastr]

The consensus is that this is a portion of a fish jaw and a scale overlaying it - there are other faint scales in the piece that look like this scale - originally thought it was a tooth because it looked like it went with the jaw or skull fragment but now agree these are scales - the coolest thing about this find is that it has led my wife and I to identify several other Lockatong sites near our home and we plan to do some exploring of these sites. This find inspired us to look harder to see what else is out there...

[Fossildude19]

Bits and pieces often lead to bigger bits and pieces.

Hopefully the spring will bring new fossils and new fossiling opportunities for you.

Keep looking at that spot - there's gotta be more there.

That is a nice Diplurus newarki scale in your latest pic! Coelacanths are a rare find in the Newark Supergroup.

Well spotted!

Regards,

Edited February 15, 2013 by Fossildude19

[squali]

Thanks for the post. It has been a pleasure to read. Nothing like a little old fashioned sleuthing to get to the bottom of a mystery. Good luck mlke and hope to see more of the lockatong in your future