Is This A Fish Otolith?

[Harry Pristis]

Is this a fish otolith? I can't think of what else it could be. It popped out of some Cretaceous matrix when I was trimming a display fossil from Morocco. There's actually another, similar object still embedded in the matrix base.

The object is transparent, with some sort of process on it roundish surface. It rolls readily, and I'm surprised that I haven't lost it in the carpet by now. It's only about 3.5mm in average diameter. But, it turned up today in a small group of bony fish teeth I had put aside.

Who can tell me about this object?

[Coco]

Hi Harry,

Is this fossil round or then it is your mode of photography that publishes it circle ? I don't manage to see its shape...

Coco

[Auspex]

Coco, I think it is a sphere, but with a folded protuberance.

[MarcoSr]

Not an otolith to me. I have seen little transparent spheres in matrix before. When they are in matrix, there is always a large number of them in varying but all very small sizes. However the ones that I have seen were perfect spheres. I thought that they were a mineral that took that shape as a result of some geologic event. But your specimen has a seam which makes me think it could be an ostracod.

Marco Sr.

[Coco]

Hi,

Ah OK. I see now. Not otolith.

Coco

[Herb]

I do not believe it is organic..

[Harry Pristis]

Frankly, I didn't know much about otoliths. Oh, I knew they existed, but they never much interested me. Sooo, after posting this question, I googled the subject. Now, I do think this object is a fish otolith, despite the negative opinions.

The round shape is not unreasonable.

The transparency/translucence is reasonable.

The size is right.

The marine matrix source is right.

The morphology is reasonable.

The 'seam' that MarcoSr believes is evidence of an ostracod, could be part of an otolith (see the generalized diagram below).

I don't know which fish donated the otolith. I did see some images on my Google search which could be clues, but nothing I could pin down. It's always possible that this otolith was altered to some unknown degree in a predator's gut before it was deposited on the bottom.

Interestingly, my two images have already been picked up by Google and showed up in my searches.

Edited July 27, 2014 by Harry Pristis

[Al Dente]

Otoliths are composed of aragonite. Aragonite is less stable than calcite. The Moroccan matrix I have searched didn't have any aragonite preserved (most mollusks with the exception of oysters, pectens and certain gastropods are aragonitic).

[Harry Pristis]

Al Dente Posted Today, 05:47 PM

Otoliths are composed of aragonite. Aragonite is less stable than calcite. The Moroccan matrix I have searched didn't have any aragonite preserved (most mollusks with the exception of oysters, pectens and certain gastropods are aragonitic).

Okay. I can't disagree with anything you say: You've never found an otolith in phosphate matrix from Morocco. I hadn't either, till I found this one, with another close by. I don't think you're arguing that because you haven't found an otolith (or a clam shell), they can't exist in Moroccan phosphate, are you?

I'm sure you know that otoliths are abundant in the fossil record, so aragonitic fossils do readily survive in some, perhaps many circumstances.

[Coco]

I never seen a perfectly round otolith... Generally they have at least a sharp side.

Coco

[Harry Pristis]

Okay, now we're talking. Be careful, Coco, about arguing from your first-hand experience: "Because I have not seen it, it must not exist."

Below are some examples of spherical otoliths. There are others. I saw one or two Oligocene examples on a research site in German, but there was no caption to the image.

Here are some tips to go with the image from a University of South Florida archeology site:

Examples of common fish otoliths found at archaeological sites in Florida. Images from the Florida Fish and Wildlife Conservation Commission ...thumbnail at bottom of this post... (http://www.flickr.com/photos/myfwc/sets/72157625872804969/

Otolith ID Tips:
Otoliths are small, irregularly shaped, and basically look like a million different things if you don’t know what you are looking at. That makes them a bit difficult to pick out of a screen during excavation, especially on prehistoric sites that are full of things like oyster shell!

Become familiar with the different shapes of otoliths from common species, catfish varieties are a good place to start. Their otoliths are fairly large and have a rounded shape that stands out a bit more than those of other species (see above).

Trying to decide whether something is an otolith or just a small piece of oyster shell? First, look to see if it is made up of rings, much like you would see inside a tree. If that doesn’t work, look for a sulcus or groove on one side of the otolith (look at the Black Drum and Sand Seatrout above for examples).

[MarcoSr]

Okay, now we're talking. Be careful, Coco, about arguing from your first-hand experience: "Because I have not seen it, it must not exist."

Below are some examples of spherical otoliths. There are others. I saw one or two Oligocene examples on a research site in German, but there was no caption to the image.

Here are some tips to go with the image from a University of South Florida archeology site:

Examples of common fish otoliths found at archaeological sites in Florida. Images from the Florida Fish and Wildlife Conservation Commission ...thumbnail at bottom of this post... (http://www.flickr.com/photos/myfwc/sets/72157625872804969/

Otolith ID Tips:

Otoliths are small, irregularly shaped, and basically look like a million different things if you don’t know what you are looking at. That makes them a bit difficult to pick out of a screen during excavation, especially on prehistoric sites that are full of things like oyster shell!

Become familiar with the different shapes of otoliths from common species, catfish varieties are a good place to start. Their otoliths are fairly large and have a rounded shape that stands out a bit more than those of other species (see above).

Trying to decide whether something is an otolith or just a small piece of oyster shell? First, look to see if it is made up of rings, much like you would see inside a tree. If that doesn’t work, look for a sulcus or groove on one side of the otolith (look at the Black Drum and Sand Seatrout above for examples).

I would still say not an otolith. Otoliths are not common at all in the matrix that I look through. I've looked through matrix from over 200 sites worldwide and probably found otoliths from a dozen or so sites. I find them in very shelly matrix which tracks with what Eric stated. The above otoliths all look recent. The fossil ones that I find are not transparent like recent ones and are white/cream/tan/yellow opaque mostly. So I'm 90% for geologic, with a 10% for something like an ostracod.

Marco Sr.

Edited July 28, 2014 by MarcoSr

[Mattalic]

Really-out-of-the-box-I-find-this-thread-interesting-thought: Sort of reminds me of a very small fish or crustacean eye lens that popped out (directional lines towards the equatorial region of the sphere).

[kauffy]

Harry have you seen this paper?

http://www.scielo.br/scielo.php?pid=S1679-87592014000600001&script=sci_arttext

It shows the extensive variation in the morphology of bony fish otoliths (no doubt there are many more that differ) however my only issue is your specimen appears to have a far greater spherical inflation than any fish otolith I have seen, represented in that paper or in my first hand experience dissecting marine fish of the Pacific (as a part of my studies).

I see structural similarities but really the inflation of your specimen is a characteristic that perplexes me. I have seen no otolith with a similar thickness or roundness...

Edited July 28, 2014 by kauffy

[Harry Pristis]

This is interesting, Mattalic . . . not a typical topic of discussion here, for sure. I thought about fish eye lenses, but I don't think they preserve like the acellular calcium carbonate of otoliths.

MarcoSr, you have fallen back on your personal experience for evidence . . . not very strong. You may have discarded dozens of beadlike otoliths, thinking they were quartz grains. The images I posted are for archeological purposes, as I mentioned. The color of a vertebrate fossil is perhaps the weakest indicator of age.

Thanks for posting the link to the atlas, Kauffy! You must be working on your Ph.D. by now! Good to hear from you.

The atlas provides images and data only for modern bony fish otoliths. The object which I argue is a fish otolith is from a Cretaceous fish. What does a Stephanodus otolith look like, for example? Just how well known are otoliths from Cretaceous fish?

[kauffy]

The atlas provides images and data only for modern bony fish otoliths. The object which I argue is a fish otolith is from a Cretaceous fish. What does a Stephanodus otolith look like, for example? Just how well known are otoliths from Cretaceous fish?

Mmm now there is an interesting thought. Harry you said there is another embedded in the matrix? Any chance you can free it and/or take a picture of it?

There is a lot of focus on the term "otolith", while I can't argue it isn't a Cretaceous fish otolith based on potentially different morphology, it appears to differ enough from the general structure of modern taxa to at least look at other possibilities. Can we rule out or delve deeper into the idea of an ostracod?

Thanks for posting this Harry, I always find I learn things when I'm forced to do a bit of research on a completely unknown object. Hope you're well.

Chris

[Auspex]

I'm still looking for any mention in the literature of an otolith in the form of a sphere....

Not finding any reference does not mean that the specimen in question is not an otolith, of course, but I am at the point of casting a larger net for clues as to what else this thing could be.

[Mattalic]

This is interesting, Mattalic . . . not a typical topic of discussion here, for sure. I thought about fish eye lenses, but I don't think they preserve like the acellular calcium carbonate of otoliths.

MarcoSr, you have fallen back on your personal experience for evidence . . . not very strong. You may have discarded dozens of beadlike otoliths, thinking they were quartz grains. The images I posted are for archeological purposes, as I mentioned. The color of a vertebrate fossil is perhaps the weakest indicator of age.

Thanks for posting the link to the atlas, Kauffy! You must be working on your Ph.D. by now! Good to hear from you.

The atlas provides images and data only for modern bony fish otoliths. The object which I argue is a fish otolith is from a Cretaceous fish. What does a Stephanodus otolith look like, for example? Just how well known are otoliths from Cretaceous fish?

Only reason I mentioned it was that some fish lenses are incredibly spherical - and I remember some old paper outlining both latitudinal and longitudinal growth (and regrowth for amphibians?) lines on some lenses. I'm just a novice, but are there any lenses that are made of harder (fish, ceph., arth...), crystalline material that would not have permitted the animal to focus (maybe just detect brightness), but would have preserved better in the record? Obviously still doesn't address the equatorial seam.

Regardless, great discussion and great little specimen. A definite thinker.

[MarcoSr]

MarcoSr, you have fallen back on your personal experience for evidence . . . not very strong. You may have discarded dozens of beadlike otoliths, thinking they were quartz grains. The images I posted are for archeological purposes, as I mentioned. The color of a vertebrate fossil is perhaps the weakest indicator of age.

Unlike you, I feel that over forty years personally searching matrix from over 200 sites from all over the world is very strong evidence. Also my point was opaque versus transparent not color. But you seem to read into the words only what supports your point of view. Unlike you, I am at least looking at beadlike objects every day under the microscope trying to determine what they are. Unlike you, I have hundreds of fossil otoliths in my collection. Unlike you, I have searched matrix from multiple sites from the Cretaceous, Paleocene and Eocene of Morocco. What you searched the web and read a few articles on otoliths and posted pictures of recent ones not fossil ones. Now that is strong evidence indeed. The fact that your specimen came up in your web search should tell you something about the validity of ids of images on the web. However, I am not closed minded on the subject. I'm still waiting to see an otolith, recent or fossil, that is an almost perfect sphere.

Marco Sr

[FossilDAWG]

Just throwing this out for consideration: what about a micro sized tektite?

Don

[Mattalic]

Just throwing this out for consideration: what about a micro sized tektite?

Don

Actually very interesting - check out some of these glass spherules: http://micrometeorites.weebly.com/miscellaneous-photos.html

[Harry Pristis]

I think it's an otolith, but I don't know it is an otolith in the way that some here know it's NOT an otolith.

I am open to the possibility of ostracod, even of 'glass spherule.' Just don't try to substitute your expertise for evidence here.

I looked at those glass tektites, Don. Some of the colorless examples are teasingly similar. But, my mystery object is two or three times the diameter of the examples presented. Plus, the example shown are simple spheres, unlike my 'otolith.'

Look at my images: See the latitudinal bands that bleed toward the sulcus at the equator. Note the structure that is perpendicular to the equator. They may be something else -- that is to be determined -- but, they could be interpreted as growth rings. It's the other interpretations that make this challenging.

I fear that I may have disposed of the second specimen. I still need to check my workshop for the source matrix fossil. Follow up with your ostracod idea, Chris.

[Auspex]

...See the latitudinal bands that bleed toward the sulcus at the equator. Note the structure that is perpendicular to the equator. They may be something else -- that is to be determined -- but, they could be interpreted as growth rings. It's the other interpretations that make this challenging.

These seemingly organic features are what nag me to keep digging for leads...

The singular "Ah Ha" moment may elude me, but even a fruitless effort is more educational than no effort

[Coco]

hi,

If you permit me, I will send your pic to a specialist of recent otoliths. I suppose that his opinion will be interesting...

Coco

[Harry Pristis]

Yes, do send the images, Coco. I think the black & white are the more useful.