Shark, Ray And Fish Micros From The Miocene Choptank Formation Of Virginia

[MarcoSr]

I don’t normally take Miocene matrix because unless it is from a lag layer or other concentrated lense the density of shark, ray and fish micros is normally very low and not worth the effort. This shelly, brown sandy Choptank layer is normally at least 40 feet high in the cliffs and not accessible. But it was nice that when a slide came down, this layer didn’t mix with the other gray non shelly layers and stayed on top. I had taken John to the site a week earlier and since he was also into micros told him to try sampling the Choptank matrix from this slide. He found some nice micros in a small amount of matrix so I also decided to take some of it home my next trip there.

Walt was kind enough to run me up to the slide in his inflatable rubber boat and pick me up when I was done wet sifting the matrix so I didn’t have to lug the matrix two miles down the beach. His boat is great to get around on in the rivers in MD and VA. We were both in the area helping at a whale dig site.

I wet sifted the matrix in the water at the site with a 1 mm sieve and brought out 3 gallons of matrix. At home I washed the matrix really well in a 1mm sieve, dried it, and then dry sifted it with both a ¼ inch sift and 1 mm sieve. A little more than half of the finally processed matrix was caught by the ¼ inch sift (about 1 ½ gallons) and the rest by the 1mm sieve (about 1 gallon). I found only a few broken Hemipristis, a single Galeocerdo and several nice small Pecten shells in the matrix caught by the ¼ inch sift. If that was all that I had found the taking of the matrix definitely wouldn’t have been worth the effort. However, I did find a good number of shark, ray and fish micros in the matrix caught by the 1mm sieve. There was a nice variety of fish and ray teeth. However, although there were a good number of shark teeth, most were Carcharhinus. I also found a good number of crab claw tips and several fish otoliths which don’t often fossilize. I’m posting the nicer and more unusual micros which I found. If you place your cursor on a JPEG image you will see the file name which will have the specimen id as best that I can determine and the specimen size.

Each matrix that I search makes me more of an avid micro tooth collector. If anyone has or can collect good matrix with shark, ray, and fish micros please send me a PM.

Marco Sr.

[Gizmo]

Great finds Marco!

[MarcoSr]

Additional specimens:

Marco Sr.

[Diego]

That is some Nice matrix there

[aurora]

never realized such tiny teeth could have serrations haha. lovin the micro material MacroSr

[Auspex]

Outstanding!

Now I'm thinking about all I missed just combing those beaches 40 years ago...

[MikeDOTB]

Great photography and display!

[mikecable]

Very nice.

[MarcoSr]

That is some Nice matrix there

Just curious, where is the site that you are sifting the matrix? Germany? The Netherlands? Belgium? Do you ever check the material that falls through your sift for micros?

Marco Sr.

[MarcoSr]

never realized such tiny teeth could have serrations haha. lovin the micro material MacroSr

Some of the teeth that I find can be as small as a meg serration. I don't often find big megs, but I can always find hundreds of micros even at sites crawling with other collectors which helps me stay excited about collecting.

Marco Sr.

[MarcoSr]

Outstanding!

Now I'm thinking about all I missed just combing those beaches 40 years ago...

I have also been collecting those beaches for 40 years. For many of those years I walked over and missed 95% of the shark, ray and fish fossils on them.

Marco Sr.

[siteseer]

Marco Sr.,

Could that "Mliobatis sp 3" be a Rhinoptera tooth?

I like the little Squalus - don't think I've seen one from the Choptank or the Miocene of that area before.

Jess

I don’t normally take Miocene matrix because unless it is from a lag layer or other concentrated lense the density of shark, ray and fish micros is normally very low and not worth the effort. This shelly, brown sandy Choptank layer is normally at least 40 feet high in the cliffs and not accessible. But it was nice that when a slide came down, this layer didn’t mix with the other gray non shelly layers and stayed on top. I had taken John to the site a week earlier and since he was also into micros told him to try sampling the Choptank matrix from this slide. He found some nice micros in a small amount of matrix so I also decided to take some of it home my next trip there.

Walt was kind enough to run me up to the slide in his inflatable rubber boat and pick me up when I was done wet sifting the matrix so I didn’t have to lug the matrix two miles down the beach. His boat is great to get around on in the rivers in MD and VA. We were both in the area helping at a whale dig site.

I wet sifted the matrix in the water at the site with a 1 mm sieve and brought out 3 gallons of matrix. At home I washed the matrix really well in a 1mm sieve, dried it, and then dry sifted it with both a ¼ inch sift and 1 mm sieve. A little more than half of the finally processed matrix was caught by the ¼ inch sift (about 1 ½ gallons) and the rest by the 1mm sieve (about 1 gallon). I found only a few broken Hemipristis, a single Galeocerdo and several nice small Pecten shells in the matrix caught by the ¼ inch sift. If that was all that I had found the taking of the matrix definitely wouldn’t have been worth the effort. However, I did find a good number of shark, ray and fish micros in the matrix caught by the 1mm sieve. There was a nice variety of fish and ray teeth. However, although there were a good number of shark teeth, most were Carcharhinus. I also found a good number of crab claw tips and several fish otoliths which don’t often fossilize. I’m posting the nicer and more unusual micros which I found. If you place your cursor on a JPEG image you will see the file name which will have the specimen id as best that I can determine and the specimen size.

Each matrix that I search makes me more of an avid micro tooth collector. If anyone has or can collect good matrix with shark, ray, and fish micros please send me a PM.

Carcharhinus sp.1 7mm.jpgCarcharhinus sp.2 7mm.jpgCarcharhinus sp.3 5mm.jpgNegaprion sp.1 5mm.jpgNegaprion sp.2 5mm.jpgNegaprion sp.3 6mm.jpgSqualus sp,1 2mm.jpg

Aetobatis sp. 14mm.jpgDasyatis sp.1 3mm.jpgDasyatis sp.2 1.5mm.jpgMyliobatis sp.1 9mm.jpgMyliobatis sp.2 8mm.jpgMyliobatis sp.3 6mm.jpgRaja sp.1 1mm.jpgRaja sp.2 1mm.jpgRay barb 10mm.jpgRhynchobatus sp. 2mm.jpg

Marco Sr.

[MarcoSr]

Marco Sr.,

Could that "Mliobatis sp 3" be a Rhinoptera tooth?

I like the little Squalus - don't think I've seen one from the Choptank or the Miocene of that area before.

Jess

Jess

I actually found two Squalus teeth in the matrix. I also was surprised to see them. I have found lots of Squalus in the Paleocene and some Squalus in the Eocene of VA, but these are the first from the Miocene. Although I don't usually take a lot of Miocene matrix from VA because the tooth concentration is usually very low in most formations.

I can definitely tell a Myliobatis dental plate from one from a Rhinoptera. However, I still have problems telling the individual teeth apart. I usually do use the roots to tell them apart and can see why you think that tooth is a Rhinoptera. Do you have a few quick rules that you use to tell Myliobatis individual teeth apart from those of Rhinoptera? I use width to length ratios to help tell certain species of Myliobatis apart.

Marco Sr.

[Al Dente]

I actually found two Squalus teeth in the matrix. I also was surprised to see them. I have found lots of Squalus in the Paleocene and some Squalus in the Eocene of VA, but these are the first from the Miocene. Although I don't usually take a lot of Miocene matrix from VA because the tooth concentration is usually very low in most formations.

I find Squalus in the Miocene Pungo River Formation. They are tiny, usually they will pass through a 1 mm. screen. I think the Pungo River is slightly older than the Choptank. Here is a picture of one. Notice the root is heavily mineralized which is common for tiny teeth in the Pungo River.

[MarcoSr]

I find Squalus in the Miocene Pungo River Formation. They are tiny, usually they will pass through a 1 mm. screen. I think the Pungo River is slightly older than the Choptank. Here is a picture of one. Notice the root is heavily mineralized which is common for tiny teeth in the Pungo River.

squalus2.jpg

Really nice Squalus! The Pungo is older than the Choptank. For years I used window screen to sift the Pungo matrix so I missed a lot of the real small micros. That is probably why I don't have a Squalus from the Pungo. I prefer to use now a .5mm sift but when I'm wet sifting matrix at a site like I just did to get the Choptank matrix, I usually can't use the .5mm sift because it just clogs up. I've found that for almost all Cretaceous matrix, Miocene matrix from Bakersfield CA and Oligocene matrix from SC that you really should use a .5mm sift. Like you said for the Pungo, species will fall through even a 1mm sift. For some Cretaceous matrix I even use a .4mm sift to catch some Rhinobatos and Pararhincodon. Pararhincodon is not as rare as stated, just a lot smaller usually than the larger specimens which people find rarely. Luckily the Squalus specimens from the Choptank were 1.5 mm and 2mm so I caught them in a 1mm sift.

Marco Sr.

[siteseer]

Marco Sr.,

Today, Squalus frequents cooler water venturing into bays if the temperature is in its comfort zone (45-59 degrees Fahrenheit for the modern species, S acanthias). The Choptank was deposited after the warmest part of the Miocene but the area was still probably warmer on average than it is now so Squalus might have come close to shore only during a cooler-than-normal year. I noticed that Kent's 1994 book doesn't mention an occurrence of Squalus in the Calvert nor Choptank. Your tooth must be quite a rarity.

As for Rhinoptera, I tried to recall the reference that distinguished its teeth from Myliobatis but couldn't. I just have a note that a myliobatoid tooth clearly not as wide as "normal" is a general candidate for Rhinoptera. Also, the lingual shelf is not as flattened - more of a rounded bulge at the base of the crown. In Cappetta's original Chondrichthyes II, he said that the crown of Rhinoptera is asymmetrical in lingual and labial view.

Jess

Jess

I actually found two Squalus teeth in the matrix. I also was surprised to see them. I have found lots of Squalus in the Paleocene and some Squalus in the Eocene of VA, but these are the first from the Miocene. Although I don't usually take a lot of Miocene matrix from VA because the tooth concentration is usually very low in most formations.

I can definitely tell a Myliobatis dental plate from one from a Rhinoptera. However, I still have problems telling the individual teeth apart. I usually do use the roots to tell them apart and can see why you think that tooth is a Rhinoptera. Do you have a few quick rules that you use to tell Myliobatis individual teeth apart from those of Rhinoptera? I use width to length ratios to help tell certain species of Myliobatis apart.

Marco Sr.

[MarcoSr]

Marco Sr.,

Today, Squalus frequents cooler water venturing into bays if the temperature is in its comfort zone (45-59 degrees Fahrenheit for the modern species, S acanthias). The Choptank was deposited after the warmest part of the Miocene but the area was still probably warmer on average than it is now so Squalus might have come close to shore only during a cooler-than-normal year. I noticed that Kent's 1994 book doesn't mention an occurrence of Squalus in the Calvert nor Choptank. Your tooth must be quite a rarity.

As for Rhinoptera, I tried to recall the reference that distinguished its teeth from Myliobatis but couldn't. I just have a note that a myliobatoid tooth clearly not as wide as "normal" is a general candidate for Rhinoptera. Also, the lingual shelf is not as flattened - more of a rounded bulge at the base of the crown. In Cappetta's original Chondrichthyes II, he said that the crown of Rhinoptera is asymmetrical in lingual and labial view.

Jess

Jess

I also saw that Kent didn't mention Squalus for the Calvert or Choptank. I actually found three Squalus teeth, the one I posted, and two others with a lot of damage. I went back to the site and brought out some more Choptank matrix and will post what I found shortly. I found two more Squalus and some other really interesting specimens. The Squalus are all really small, less than 2mm. They may not be reported because of this small size and the lack of folks looking through the Miocene matrix of MD and VA. I don't usually look through Miocene matrix from MD and VA because it is usually hard to take, hard to break down but mostly because the tooth density is very low unlike this Choptank matrix..

Thank you for the tips on identifying the Rhinoptera. Myliobatis and sometimes Rhinoptera individual teeth are very common in a lot of the formations that I collect in. I just haven't taken the time to study the individual medial teeth. I just look at then for half a second and then put them away. I spend even less time on the lateral teeth. Two dimensional pictures and descriptions do help me to identify my specimens. But not until I hold a specimen in my hand and concentrate on a feature and form a mental image does the feature stick with me for future identifications.

Marco Sr.

[siteseer]

Marco Sr.,

I've done a lot of collecting in the Sharktooth Hill Bonebed. I have just one tooth that I consider Rhinoptera. The climate was probably too cool for the genus except maybe during an unusually warm (El Nino?) year. Myliobatoid teeth are actually not that common and plates with more than two teeth are another level of rarity. I have been hoping to find a Rhinoptera plate or at least see one in another collection, but no luck so far.

I have seen some isolated Rhinoptera teeth from the Rosarito Beach Formation, Middle Miocene of La Mision, Baja California, Mexico. It's about the same age as STH but closer to the equator - more of a tropical fauna with big lemon sharks, more Hemipristis, etc.

Jess

Jess

I also saw that Kent didn't mention Squalus for the Calvert or Choptank. I actually found three Squalus teeth, the one I posted, and two others with a lot of damage. I went back to the site and brought out some more Choptank matrix and will post what I found shortly. I found two more Squalus and some other really interesting specimens. The Squalus are all really small, less than 2mm. They may not be reported because of this small size and the lack of folks looking through the Miocene matrix of MD and VA. I don't usually look through Miocene matrix from MD and VA because it is usually hard to take, hard to break down but mostly because the tooth density is very low unlike this Choptank matrix..

Thank you for the tips on identifying the Rhinoptera. Myliobatis and sometimes Rhinoptera individual teeth are very common in a lot of the formations that I collect in. I just haven't taken the time to study the individual medial teeth. I just look at then for half a second and then put them away. I spend even less time on the lateral teeth. Two dimensional pictures and descriptions do help me to identify my specimens. But not until I hold a specimen in my hand and concentrate on a feature and form a mental image does the feature stick with me for future identifications.

Marco Sr.

[MarcoSr]

Marco Sr.,

I've done a lot of collecting in the Sharktooth Hill Bonebed. I have just one tooth that I consider Rhinoptera. The climate was probably too cool for the genus except maybe during an unusually warm (El Nino?) year. Myliobatoid teeth are actually not that common and plates with more than two teeth are another level of rarity. I have been hoping to find a Rhinoptera plate or at least see one in another collection, but no luck so far.

I have seen some isolated Rhinoptera teeth from the Rosarito Beach Formation, Middle Miocene of La Mision, Baja California, Mexico. It's about the same age as STH but closer to the equator - more of a tropical fauna with big lemon sharks, more Hemipristis, etc.

Jess

Jess

Myliobatis individual teeth and even plates are fairly common at a Paleocene site in Maryland. If you search the gravel on your hands and knees you can find several hundred individual Myliobatis medial teeth from multiple species. When I used to take home 3 gallons of fine river gravel to search for micros I would find a hundred or so Myliobatis medial teeth and almost as many lateral teeth. There was an Eocene dig site in Virginia which is now closed where you could bring out matrix where you would find a couple hundred Myliobatis medial teeth and lateral teeth of at least three species per trip. You could also find Rhinoptera that were identified as sherboni. These Rhinoptera were easy to distinguish from Myliobatis because they had extremely flat crowns and roots, a lot had a slight curvature, and the roots really looked a lot different. Because the Myliobatis individual medial and lateral teeth are so common in the Paleocene and Eocene of Maryland and Virginia where I usually collect, I never really studied them that closely. However, Miocene Myliobatis individual teeth and Rhinoptera individual teeth are not as common here at all. I find a lot more Aetobatus individual teeth at the site where I took this Choptank matrix than I find Myliobatis individual teeth. The few Miocene Rhinoptera that I have found also look a lot more similar to the Miocene Myliobatis and I still struggle telling them apart.

Marco Sr.

[ClearLake]

@MarcoSr

I realize this post is many years old and maybe that is why the ID's no longer work when you hover over each picture so I am wondering if you would mind telling me what you ID'd the numbered specimens as.  I have some from Florida that look very similar and I'm hoping you got a bit further with an ID than I have so far.  Thanks

 

[MarcoSr]

2 hours ago, ClearLake said:

@MarcoSr

I realize this post is many years old and maybe that is why the ID's no longer work when you hover over each picture so I am wondering if you would mind telling me what you ID'd the numbered specimens as.  I have some from Florida that look very similar and I'm hoping you got a bit further with an ID than I have so far.  Thanks

 

 

 

Individual fish teeth are extremely difficult to ID because so many genera/species have very similar looking teeth.  At best, I'll only label a fish tooth to a genus.  I only labeled 1 through 6 as fish teeth.  7 & 8 as Pogonias sp.  9 & 10 as Tautoga sp. (from the pharyngeal jaw)   I labeled 7 through 10 because those two genera are common in the Choptank Formation layer where these specimens came from and the tooth features of the specimens matched teeth from those genera.  I'm the most certain of the ID of the two Lagodon sp. teeth that you didn't ask about because they are also found in that Choptank layer and their tooth features are more unique.

 

Marco Sr.

[ClearLake]

 

40 minutes ago, MarcoSr said:

 

 

Individual fish teeth are extremely difficult to ID because so many genera/species have very similar looking teeth.  At best, I'll only label a fish tooth to a genus.  I only labeled 1 through 6 as fish teeth.  7 & 8 as Pogonias sp.  9 & 10 as Tautoga sp. (from the pharyngeal jaw)   I labeled 7 through 10 because those two genera are common in the Choptank Formation layer where these specimens came from and the tooth features of the specimens matched teeth from those genera.  I'm the most certain of the ID of the two Lagodon sp. teeth that you didn't ask about because they are also found in that Choptank layer and their tooth features are more unique.

 

Marco Sr.

That is excellent, thank you for the quick response. I don’t feel so bad now on 1-6 that I had similar teeth in my group of “unidentified fish teeth”. I was hopeful that the ones I have very similar to #5 might be identifiable since I thought they were pretty  neat looking, but I guess that doesn’t count for much - haha. I probably have all my teeth that look like 7-10 in my Pogonias group, I’ll have to learn about Tautoga to see if that is an option for me. I didn’t ask about the two Lagodon teeth because I felt pretty good about that ID after reading the couple of papers by Caldwell, but thanks for confirming. Again, thanks for the help

 

Mike

[MarcoSr]

6 hours ago, ClearLake said:

 

That is excellent, thank you for the quick response. I don’t feel so bad now on 1-6 that I had similar teeth in my group of “unidentified fish teeth”. I was hopeful that the ones I have very similar to #5 might be identifiable since I thought they were pretty  neat looking, but I guess that doesn’t count for much - haha. I probably have all my teeth that look like 7-10 in my Pogonias group, I’ll have to learn about Tautoga to see if that is an option for me. I didn’t ask about the two Lagodon teeth because I felt pretty good about that ID after reading the couple of papers by Caldwell, but thanks for confirming. Again, thanks for the help

 

Mike

 

When they updated TFF software a few years back, the ability to mouse over a JPEG picture and see the file name was lost.  My file names also contained size information.  9 & 10 are only 1 mm and 1.5 mm in diameter.  7 & 8 are 5 mm wide.  So there is a big size difference.  At one point I did have an ID for fish teeth like #5 because the features are somewhat unique.  However, I have many thousands of pictures from over 200 fossil sites and I can't find the pictures with the ID.

 

Marco Sr.

[Al Dente]

The otoliths look like ones that Muller called "genus aff. Sciaenops" paraeastmani n. sp. Numbers 1 and 2 in the drawing are from the Choptank.

 

 

Edited October 27, 2021 by Al Dente

[ClearLake]

4 hours ago, MarcoSr said:

At one point I did have an ID for fish teeth like #5 because the features are somewhat unique.  However, I have many thousands of pictures from over 200 fossil sites and I can't find the pictures with the ID.

This gives me hope that I might come across some reference to ID them.  The curse of an extensive collection!  I appreciate your diligence and expertise, thanks again for your thoughts.