Al Dente Posted August 7, 2014 Share Posted August 7, 2014 The recent posts on dermal denticles have made me want to post some photos of denticles that are in my collection. I've been photographing these for the past few years. Most dermal denticles are too small for me to attempt to adequately photograph so I only photograph the larger denticles that are sometimes called "Thorns". I'll start with the modern ones. Recent Male clearnose skates (Raja eglanteria) are covered with a variety of thorns. Here's a few from a single individual: And here are detailed images of some of the thorns. I've toasted these in the oven to darken them. I have problems photographing bright white objects through my microscope. Dasyatis sabina are the most common stringray that I catch. They have a row of denticles down their back and some have star shaped denticles on the head. Here's a cluster of denticles from between the eyes. 2 1 Link to comment Share on other sites More sharing options...
Al Dente Posted August 7, 2014 Author Share Posted August 7, 2014 Here's a patch of skin from a Rhinobatos (guitarfish): And a patch of skin from an angel shark Squatina dumeril: 3 Link to comment Share on other sites More sharing options...
Al Dente Posted August 7, 2014 Author Share Posted August 7, 2014 Pliocene The huge denticles from Dasyatis centroura are found from Pliocene sediments. I haven't included these large "bucklers", just smaller thorns. I haven't found many in the Pliocene, mostly from lack of screening of this material. Here are a couple. The first one is most likely from a skate: 2 1 Link to comment Share on other sites More sharing options...
Al Dente Posted August 7, 2014 Author Share Posted August 7, 2014 Miocene Pungo River Formation - NC All these Pungo River denticles are from the black phosphatic sands that I carried out of the Lee Creek Mine in buckets. The thorns are usually in good condition when collected this way. Material from the reject piles is heavily abraded and the thorns are usually broken if they survive at all. 2 1 Link to comment Share on other sites More sharing options...
Al Dente Posted August 7, 2014 Author Share Posted August 7, 2014 Miocene Round Mountain Silt - California I haven't had much opportunity to collect from the Round Mountain Silt but it is loaded with denticles. I still have a lot of types to photograph but here are a few that I've already completed. This last one is very similar to Oligocene denticles from NC that have been identified as Squatina 2 1 Link to comment Share on other sites More sharing options...
jpc Posted August 7, 2014 Share Posted August 7, 2014 Beautiful photos... and very nice little collection. Link to comment Share on other sites More sharing options...
Al Dente Posted August 7, 2014 Author Share Posted August 7, 2014 Oligocene The River Bend Formation in North Carolina produces a variety of tiny denticles but this type is the only one I would call a thorn. These are fairly numerous and a publication on the fauna by Gerard Case identifies these as Squatina denticles. Eocene Nothing. I collect the Eocene Castle Hayne on a regular basis and have never found a denticle larger than a millimeter. My guess is the warm temperatures didn't favor the skates. There are not many Dasyatis remains found. The "Eagle rays" were plentiful but they probably didn't have much in the way of denticles. Paleocene Not much besides some blocky types that I have yet to photograph. I don't collect much in the Paleocene but will continue looking. 1 1 Link to comment Share on other sites More sharing options...
Al Dente Posted August 7, 2014 Author Share Posted August 7, 2014 Cretaceous I haven't photographed much of my Cretaceous collection. Most of my Cretaceous sites are from reworked deposits so delicate denticles might be destroyed. Here are a few of the more common types. The first is a common "blocky" type denticle. I've seen similar in the Paleocene of Maryland. This type might be a rostral tooth from a Ptychotrygon. I'll call it a denticle for now. These are interesting. At least one author has called these fish teeth. Others have correctly identified them as denticles. These are very common in some deposits. I still have a lot to photograph and may add more over the next year or two. 2 1 Link to comment Share on other sites More sharing options...
Harry Pristis Posted August 7, 2014 Share Posted August 7, 2014 Excellent microscope photography! You must have the patience of Job, Al Dente! http://pristis.wix.com/the-demijohn-page What seest thou else In the dark backward and abysm of time? ---Shakespeare, The Tempest Link to comment Share on other sites More sharing options...
RyanNREMTP Posted August 7, 2014 Share Posted August 7, 2014 Pretty cool. Great photos. Link to comment Share on other sites More sharing options...
sixgill pete Posted August 7, 2014 Share Posted August 7, 2014 Great post Eric. I have a few denticles from some of the same locations. Now, I have something to compare them too. Bulldozers and dirt Bulldozers and dirt behind the trailer, my desert Them red clay piles are heaven on earth I get my rocks off, bulldozers and dirt Patterson Hood; Drive-By Truckers May 2016 May 2012 Aug 2013, May 2016, Apr 2020 Oct 2022 Link to comment Share on other sites More sharing options...
powelli1 Posted August 7, 2014 Share Posted August 7, 2014 WOW these photos are great and the collection is well what can I say . This is the way we all should do our fossils for all to see, if only I could. THANKS George Link to comment Share on other sites More sharing options...
fossilselachian Posted August 7, 2014 Share Posted August 7, 2014 Superb contribution to TFF! The oven idea is great. Link to comment Share on other sites More sharing options...
Coco Posted August 7, 2014 Share Posted August 7, 2014 It is a nice subject Al Dente ! I have to do pics of mine (recent)... Coco ---------------------- OUTIL POUR MESURER VOS FOSSILES : ici Ma bibliothèque PDF 1 (Poissons et sélaciens récents & fossiles) : ici Ma bibliothèque PDF 2 (Animaux vivants - sans poissons ni sélaciens) : ici Mâchoires sélaciennes récentes : ici Hétérodontiques et sélaciens : ici Oeufs sélaciens récents : ici Otolithes de poissons récents ! ici Un Greg... Link to comment Share on other sites More sharing options...
MarcoSr Posted August 7, 2014 Share Posted August 7, 2014 Eocene Nothing. I collect the Eocene Castle Hayne on a regular basis and have never found a denticle larger than a millimeter. My guess is the warm temperatures didn't favor the skates. There are not many Dasyatis remains found. The "Eagle rays" were plentiful but they probably didn't have much in the way of denticles. Paleocene Not much besides some blocky types that I have yet to photograph. I don't collect much in the Paleocene but will continue looking. Eric Great post!!!! I have trouble also taking pictures of white objects through my microscope even on black backgrounds. That one denticle does look like what a number of authors are calling a Ptychotrygon rostral tooth. I have a large number of Eocene denticles from VA and some from the UK. I also have a number of denticles from the Paleocene of MD. Unfortunately I need to take pictures of them. Marco Sr. "Any day that you can fossil hunt is a great day." My family fossil website Some Of My Shark, Ray, Fish And Other Micros My Extant Shark Jaw Collection Link to comment Share on other sites More sharing options...
MarcoSr Posted August 7, 2014 Share Posted August 7, 2014 Here's a patch of skin from a Rhinobatos (guitarfish): Rhinobatos.small.jpg And a patch of skin from an angel shark Squatina dumeril: Squatina dermal denticles1.jpg Some examples of fossil dermal denticles: Miocene of VA Oligocene of SC Eocene of SC Marco Sr. 1 "Any day that you can fossil hunt is a great day." My family fossil website Some Of My Shark, Ray, Fish And Other Micros My Extant Shark Jaw Collection Link to comment Share on other sites More sharing options...
lissa318 Posted August 7, 2014 Share Posted August 7, 2014 Great post, specimens and pictures!!! Thanks! Link to comment Share on other sites More sharing options...
Al Dente Posted August 8, 2014 Author Share Posted August 8, 2014 (edited) Marco- Your Eocene specimen looks like ones I find in the Oligocene River Bend Formation. A similar one was published from the Chandler Bridge Formation - "Late Oligocene sharks and rays from the Chandler Bridge Formation, Dorchester County, SC, USA". In that paper they call it a Cetorhinus denticle. Pictures of modern Cetorhinus denticles that I have seen don't look much like this. They do mention Squatina as a possibility and I think that is a good comparison. Here is my modern Squatina skin with your denticle superimposed along with the Chandler Bridge denticle. Edited August 8, 2014 by Al Dente Link to comment Share on other sites More sharing options...
MarcoSr Posted August 8, 2014 Share Posted August 8, 2014 Marco- Your Eocene specimen looks like ones I find in the Oligocene River Bend Formation. A similar one was published from the Chandler Bridge Formation - "Late Oligocene sharks and rays from the Chandler Bridge Formation, Dorchester County, SC, USA". In that paper they call it a Cetorhinus denticle. Pictures of modern Cetorhinus denticles that I have seen don't look much like this. They do mention Squatina as a possibility and I think that is a good comparison. Here is my modern Squatina skin with your denticle superimposed along with the Chandler Bridge denticle. Squatina comparison.jpg Eric Definitely looks like a match. This specimen came from matrix that I got from Larry Martin from the Orangeburg Formation in the LaFarge Quarry. This is the same matrix in which I found a good number of Pristiophorus oral teeth. According to Larry "The matrix I sent was not from the quarry proper, it was from a sink hole, a solution hole, on the east quarry wall & it didn't go down to the quarry bottom." Marco Sr. "Any day that you can fossil hunt is a great day." My family fossil website Some Of My Shark, Ray, Fish And Other Micros My Extant Shark Jaw Collection Link to comment Share on other sites More sharing options...
JackS Posted October 13, 2021 Share Posted October 13, 2021 Hey everyone. I was wondering if anyone had any idea on what species this dermal denticle could be from? From Hell Creek Formation. For scale, the diameter of the pencil lead is 700 microns Link to comment Share on other sites More sharing options...
Fossildude19 Posted October 13, 2021 Share Posted October 13, 2021 Cropped and brightened: Tim - VETERAN SHALE SPLITTER VFOTM --- APRIL - 2015 __________________________________________________ "In every walk with nature one receives far more than he seeks." John Muir ~ ~ ~ ~ ><))))( *> About Me Link to comment Share on other sites More sharing options...
Al Dente Posted October 13, 2021 Author Share Posted October 13, 2021 4 hours ago, JackS said: Hey everyone. I was wondering if anyone had any idea on what species this dermal denticle could be from? From Hell Creek Formation. For scale, the diameter of the pencil lead is 700 microns It looks more like a sawfish rostral tooth than a dermal denticle. I think Ischyrhiza avonicola has been found in the Hell Creek. 2 Link to comment Share on other sites More sharing options...
JackS Posted October 13, 2021 Share Posted October 13, 2021 1 hour ago, Al Dente said: It looks more like a sawfish rostral tooth than a dermal denticle. I think Ischyrhiza avonicola has been found in the Hell Creek. Amazing. Thanks for the help Link to comment Share on other sites More sharing options...
siteseer Posted October 14, 2021 Share Posted October 14, 2021 I thought it might be a Ptychotrygon rostral spine but don't know of a report of the genus from the Hell Creek Formation. It wouldn't be impossible but it would seem more likely that it is a small I. avonicola spine. 1 Link to comment Share on other sites More sharing options...
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