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Harry Pristis

Ray Dermal Denticles

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Harry Pristis

Ray parts appear from time to time in the ID section. I thought I'd post an image of a variety of dermal denticles (literally, "skin teeth") from the back and tail (mostly) of Late Miocene rays from Florida.

Dermal denticles have the same embryological origin as the teeth in the ray mouth. These are teeth that have "migrated" to the skin.

post-42-094870700 1285357586_thumb.jpg

Edited by Harry Pristis

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siteseer

Harry,

All those dermal denticles fit within the morphological range of stingrays, Dasyatis, according to Purdy et al. (2001: 92). They went a step further with identical material from the Yorktown Formation, referring it to the species, D, centroura.

For years I had seen these identified as "skate dermal denticles" and I'd always wondered about the ID because I had never read about how the distinction was made. That seemed to be how similar finds from STH or Ridgeville (South Carolina) were also tagged. I had never seen stingray or true skate teeth from the Bone Valley Formation and the book "The Fossil Vertebrates of Florida" (Wing in Hulbert, 2001) offers no assistance as it doesn't adequately figure any ray teeth except for those of some myliobatids.

Years ago, while prepping a Bone Valley dolphin skull in its field jacket, I saved the matrix out of habit and later screened it. I did find a couple of stingray teeth and some kind of guitarfish as well (possibly Rhynchobatus). It would seem unlikely that skates would be known from the Bone Valley Formation as the fauna indicates warm-water/shallow water forms while skates generally frequent cool water/deeper water.

Wing (in Hulbert, 2001) stated that "skate teeth are small and buttonlike." More precise adjectives are required for skate teeth as some are quite small, as in around 1mm long. Female teeth tend to bear lower-cusped crowns while male teeth have tall, pointed crowns like sharks, though not in all species with jaw position sometimes a factor as well (see Herman et al, 1995).

Herman, J., M. Hovestadt-Euler, D.C. Hovestadt, and M. Stehmann. 1995.

Part B. Batomorphii No. 1b: Order Rajiformes - Suborder Rajoidei - Family: Rajidae - Genera and Subgenera: Bathyraja (with deep-water, shallow-water and transitional morphotype), Psammobatis, Raja (Amblyraja), Raja (Dipturus), Raja (Leucoraja), Raja (Raja), Raja (Rajella) (with two morphotypes), Raja (Rioraja), Raja (Rostroraja), Raja lintea, and Sympterygia. In M. Stehmann. Contributions to the study of the comparative morphology of teeth and other relevant ichthyodorulites in living supra-specific taxa of Chondrichthyan fishes. Bulletin de l'Institut Royal des Sciences Naturelles de Belgique. Biologie 65: 237-307.

Ray parts appear from time to time in the ID section. I thought I'd post an image of a variety of dermal denticles (literally, "skin teeth") from the back and tail (mostly) of Late Miocene rays from Florida.

Dermal denticles have the same embryological origin at the teeth in the ray mouth. These are teeth that have "migrated" to the skin.

post-42-094870700 1285357586_thumb.jpg

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Harry Pristis

Thanks for the information, Jess.

I am not familiar with Purdy 2001. Gerard Case figures these denticles in his various guides and refers to them, as you say, as from skates (Rajidae) or stingrays (Dasyatidae) without trying to distinguish between the two. Case does specify (in an off-hand sort of way) that the serrated blades belong to the stingrays.

Hulbert seems content to let the distinction go unresolved.

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CreekCrawler

Here is one that I collected from the Upper Cretaceous.

It is from the Maestrichtian,Navarro group

We find plenty of Rhombodus binkhorsti teeth at this location and one Myliobatidae tooth plate that probably traveled down to this location from the Campanian via the Ozan fm.

I'm not sure which species this belongs to and I am open for suggestions.It measures 1/2" across the base and 3/4" high.

thanks

post-417-078709800 1285472786_thumb.jpg

post-417-046737500 1285472817_thumb.jpg

post-417-050166100 1285472830_thumb.jpg

post-417-089339600 1285472843_thumb.jpg

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emmytee

very cool info! thanks for sharing!

-emily

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non-remanié

Nice denticle. I have a couple of this type from the late Campanian Wenonah fm of NJ, but they are extremely rare. We get 2 other types of denticles which are more common and have been attributed to Brachyrhizodus wichitaensis and Rhombodus laevis, but Arambourg attributes a specimen like yours to Rhombodus so something doesn't add up.

http://home.zonnet.nl/jbastiaansen/maastr_rays.html

Jess do you happen to have this paper? I'm wondering what the 5 denticle types in there look like.

http://www.jstor.org/pss/1306032

-steve

Here is one that I collected from the Upper Cretaceous.

It is from the Maestrichtian,Navarro group

We find plenty of Rhombodus binkhorsti teeth at this location and one Myliobatidae tooth plate that probably traveled down to this location from the Campanian via the Ozan fm.

I'm not sure which species this belongs to and I am open for suggestions.It measures 1/2" across the base and 3/4" high.

thanks

post-417-078709800 1285472786_thumb.jpg

post-417-046737500 1285472817_thumb.jpg

post-417-050166100 1285472830_thumb.jpg

post-417-089339600 1285472843_thumb.jpg

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Shellseeker

Speak of the devil,

I had never even seen one of these. Yesterday PeaceFossil and I went to Arcadia and within the 1st hour, I picked this up originally thinking that it was some type of palm frond juncture. Then I bit it an realized it was something else. I showed it to PeaceFossil and he mentioned this thread and told me it was some sort of Ray dermal migrating tooth..

I am please to find it, because it is a first for me. It also shows the value of just posting details of different fossils that "might" be found. I have learned something new today.

EDITED:

from the back and tail (mostly) of Late Miocene rays from Florida.

I thought I was finding Pleistocene materials at Arcadia. There are plenty of MYAs between Pleistocene and Miocene.

post-2220-064445000 1285508523_thumb.jpg

Edited by Shellseeker

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Auspex

...it is a first for me...

Well, you started with one of the nicer ones I've seen :wub:

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peacefossil

Speak of the devil,

I had never even seen one of these. Yesterday PeaceFossil and I went to Arcadia and within the 1st hour, I picked this up originally thinking that it was some type of palm frond juncture. Then I bit it an realized it was something else. I showed it to PeaceFossil and he mentioned this thread and told me it was some sort of Ray dermal migrating tooth..

I am please to find it, because it is a first for me. It also shows the value of just posting details of different fossils that "might" be found. I have learned something new today.

EDITED:

I thought I was finding Pleistocene materials at Arcadia. There are plenty of MYAs between Pleistocene and Miocene.

Glad I could help! Very nice piece you found. I don't think the peace is miocene mix, but maybe someone will chime in.

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Harry Pristis

Glad I could help! Very nice piece you found. I don't think the peace is miocene mix, but maybe someone will chime in.

I am non-plussed. Did you fellows believe that all those shark teeth were Pleistocene in age? Have you read the intro to Hulbert's book?

The age of the [marine] Hawthorn Group ranges from the very early Miocene (possibly latest Oligocene) to early Pliocene.

The last major sea-level high stand was during the Pliocene, between 4.5 and 2.5 Ma. At this time most, if not all, of Florida was below seal level for the last time in geologic history. No fossils of land animals are known from this interval, only marine vertebrates....

In other words, the marine fossils you're finding in the Peace River are Miocene to Pliocene in age, or "Mio-Pliocene" if you like.

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Shellseeker

Harry,

When I miss something so obvious, sometimes I just have to smack my forehead. This is an epiphany... and at first I struggled on how I managed to miss it over the last 18 months -- which is when i first started to collect fossils.

I am trying to do this on the cheap -- just picking up "facts" in conversations or in what I see on this forum. That means I am not reading the books and do not read Hulbert's book, although I listened to one of his presentations. Every minute I have outside of work , I am seeking the fossil.

For whatever reasons, my first fossils were mammoth teeth, Llama ear bones, tapir bones, Equus, etc from a quarry and then Bison, horse, tapir, capabara teeth, and giant Armadillo and Glyptodon and alligator osteoderms.. Get the picture -- all Pleistocene.. and all land animals The shark teeth I found were mostly small and easily identified, same with ray plates and teeth -- never really asked about age..

So, YES I made the foolish connection between finding Pleistocene fossils and assuming that the shark and ray teeth were also Pleistocene... :wacko:

It makes so much sense and I was so wrong... so now I have a 5-23 mya Ray dermal denticle rather than a 50k-1.5 mya fossil -- sounds good to me :D !!! I am just amazed on how nice it is preserved after 5-23 mya..

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siteseer

It's the third Lee Creek volume - Smithsonian Contributions to Paleobiology No. 90. It covers the fishes, reptiles, and birds known from the Lee Creek Mine, NC.

From what I've read the tail spines can belong to either dasyatids or myliobatids.

Thanks for the information, Jess.

I am not familiar with Purdy 2001. Gerard Case figures these denticles in his various guides and refers to them, as you say, as from skates (Rajidae) or stingrays (Dasyatidae) without trying to distinguish between the two. Case does specify (in an off-hand sort of way) that the serrated blades belong to the stingrays.

Hulbert seems content to let the distinction go unresolved.

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siteseer

Steve,

I looked for that but couldn't find it (looks very familiar, though). I can certainly make an effort to make a copy for you on my next trip to the USGS though.

Nice denticle. I have a couple of this type from the late Campanian Wenonah fm of NJ, but they are extremely rare. We get 2 other types of denticles which are more common and have been attributed to Brachyrhizodus wichitaensis and Rhombodus laevis, but Arambourg attributes a specimen like yours to Rhombodus so something doesn't add up.

Jess do you happen to have this paper? I'm wondering what the 5 denticle types in there look like.

http://www.jstor.org/pss/1306032

-steve

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siteseer

This one is similar to Neogene Dasyatis denticles and that genus is known from the Maastrichtian of Texas with Dasyatis-like teeth known from earlier in the Cretaceous as well. The problem with fossil dermal denticles is that they are not often included in faunal reviews. Relatively few articles are written on them.

Here is one that I collected from the Upper Cretaceous.

It is from the Maestrichtian,Navarro group

We find plenty of Rhombodus binkhorsti teeth at this location and one Myliobatidae tooth plate that probably traveled down to this location from the Campanian via the Ozan fm.

I'm not sure which species this belongs to and I am open for suggestions.It measures 1/2" across the base and 3/4" high.

thanks

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peacefossil

Harry, No I'll have to admit I have not read Hulbert yet. Facepalm here as well :D

We are amateurs and appreciate all that you can learn us!

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fossilselachian

Here is a dermal denticle collected from Lee Creek. The conical point has been somewhat damaged.

post-294-041062100 1285606654_thumb.jpg

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Auspex

Here is a dermal denticle collected from Lee Creek...

Just about the biggest I've ever seen! :o

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Shellseeker

Here is a dermal denticle collected from Lee Creek. The conical point has been somewhat damaged.

It is nice, and I am new to these fossils.. Am I looking at the bottom or the top? What are the grooves coming toward me, and the circular impression in the center? What connects to the "conical point" ?

I am trying to envision the animal and where this fossil fits. Thanks

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siteseer

You are looking at the top. The grooves are striations that occur on denticles situated on the tail of the stingray genus Dasyatis (see Bigelow & Schroeder, 1953 - the volume on batoids). Denticles on the body tend to have smoother surfaces though can have an irregular textures based on what I've seen. I don't know why denticles on the tail would have striations while body denticles would not but it might be related to hydrodynamics.

I have a specimen from Ridgeville, South Carolina (Pliocene deposit) very similar to that one. Mine has a less-complete base but the spine is more complete (worn at the tip). On mine the impression is not rounded (more linear and open-ended on the side pointing in the opposite direction of the point) indicating that the shape varies perhaps randomly, perhaps depending on the position on the tail (or perhaps the body). The point and the rest of the shiny part make up the spine which may serve a defensive and hydrodynamic function.

It is nice, and I am new to these fossils.. Am I looking at the bottom or the top? What are the grooves coming toward me, and the circular impression in the center? What connects to the "conical point" ?

I am trying to envision the animal and where this fossil fits. Thanks

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non-remanié

i wouldnt mind looking at the plate of the denticles to see ones that may belong to some rajiformes, but its not necessary, i just figured there would be at least a 50/50 chance you have the paper already :)

Steve,

I looked for that but couldn't find it (looks very familiar, though). I can certainly make an effort to make a copy for you on my next trip to the USGS though.

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tomclark

I like these things and pick them up over small shark's teeth anyday.

All of these were on ONE phosphate mine "Bluish" pile. I took this pic of what was found on that pile. At mines, you can look over large areas and concentrate on the phosphate-pebble heavy piles that are fewer. Not all piles produce as many of you know. In Bone Valley, it's the one's with darker and bluer pebble/fossil that produce the most. They can be absolutely loaded with fossils. Same areas can be seen on the Peace because most of it was dredged out and these particular loaded piles are here and there. Here's a scientific explanatory exposition about these piles for nerdy, brainy fossil collectors who may want to know what I think I know. When they are dredging, they take off the overburden to reach the phosphate layer. So there are many sand piles. They want the phosphate pebble. When they get to that layer they get it all slurried up with water in a slurry pit/lag pit to pump it out of the mine. In that slurry pit, due to the hydrodynamics blah balh of the particles in the slurry, there begins to form these fossil/phosphate pebble piles/depositions. Maybe it's just where they were last and most of the others are covered over....

There is a huge rubble pile, pit deposit just downstream from Brownsville at the mouth of the little creek and downstream a bit and up the side of the bank on the left as you are going downstream. Similarly there is another area just upstream from Brownsville. I have strategies that pay off in both of these areas, not doing what most people do. Gawd it's boring and usually non productive to sit and screen all day in rubble that's been gone over a hundred times for a fragment of fossil. Virgin rubble is the key.

Again, all these found on one of these mine piles maybe 30 feet across somewhere between Arcadia and Bradenton-Sarasota. Back in the 50's or so yah.

dermalplates2.jpg

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danco

Here is one that I collected from the Upper Cretaceous.

It is from the Maestrichtian,Navarro group

We find plenty of Rhombodus binkhorsti teeth at this location and one Myliobatidae tooth plate that probably traveled down to this location from the Campanian via the Ozan fm.

I'm not sure which species this belongs to and I am open for suggestions.It measures 1/2" across the base and 3/4" high.

thanks

post-417-078709800 1285472786_thumb.jpg

post-417-046737500 1285472817_thumb.jpg

post-417-050166100 1285472830_thumb.jpg

post-417-089339600 1285472843_thumb.jpg

I think I have something similar (a fragment - the tip is missing, also Upper Cretaceous, Midlothian, Texas) that I attach. What do you think?

post-4401-0-83354000-1296258976_thumb.jpg

Edited by danco

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siteseer

Steve,

I stopped briefly at the USGS and photocopied the pages related to dermal denticles. Here are the descriptions for the five denticle types in Williamson et al. (1993):

Type A dermal denticle:

circular in outline, conical to nearly flat in profile; outer surface ornamented with pattern of radiating ribs which may extend to form lobes around circumference; some of more conical specimens bear central point which projects posteriorly and may possess posterior notch in base of denticle; denticles lack root and appear to be composed completely of dentine.

The discussion section notes that this form closely resembles one illustrated in Estes (1964: fig. 8d) but probably belongs to another batoid since Myledaphus is not known from the Arizona site discussed in Williamson et al. (1993)

Type B dermal denticle

circular in outline with thick orthodentine base and small enameloid-covered cap; cap low and posteriorly pointed with longitudinal ridges about base.

The discussion section expresses little doubt that it belongs to a batoid.

Type C dermal denticle

rectangular in outline and low in profile; lacks an enameloid cap and consists entirely of ortheodentine; subtle radiating ridge pattern extends from low, longitudunal ridge to perimeter

Probably a batoid

Type D dermal denticle

very small, circular outline with small enameloid-covered, posteriorly pointing cap; cap marked by strongly radiating rib pattern; base of denticle strongly ribbed with ridges extending out to perimeter.

probably referable to a batoid

Type E dermal denticle

very small with relatively small base and large posteriorly projecting crown; crown morphology varies from low angle to near-erect; crown diamond-shaped in apical view and bears strong, central longitudinal ridge flanked by two to three smaller parallel ridges.

resemble typical lamnid dermal denticles - probably from one of the lamnoid sharks known from the site

Jess

Jess do you happen to have this paper? I'm wondering what the 5 denticle types in there look like.

http://www.jstor.org/pss/1306032

-steve

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non-remanié

Thanks Jess, I had forgotten about this one!

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