Paleocene Shark, Ray, Fish, And Other Micros From The Aquia Formation Of Virginia

[JohnJ]

An awesome update to a great, older topic.

[MarcoSr]

I have a heavily serrated Squalus from the Aquia. I picked this out of a bucket of pure formation. Very few teeth but this was a nice find.

AquiaSqualusSerratedsmall.jpg

Eric

Really nice specimen! You can see what I mean from your specimen, that the heavily serrated Squaliform teeth from the Aquia Formation have features which are different from the described Squalus minor or Megasqualus orpiensis. The serrations are also much stronger than the serrations on the Squalus crenatidens which is supposed to be found in the Eocene Nanjemoy Formation of MD/VA. My Eocene specimens are also heavily serrated like these heavily serrated Aquia specimens. I am trying to get a shark researcher to re-look at the Squaliform teeth from the Aquia and Nanjemoy Formations. He is currently studying and describing Centrophorus from the Paleocene and Eocene from the West Coast of the US. I've sent him a bunch of pictures and he agrees that the Aquia Formation Squaliforms really should be restudied and re-described. However, he has so many current projects that he wouldn't be able to do it near term.

Marco Sr.

[Otodusobliquus]

Marco, I have been collecting and searching Aquia formation matrix recently and wonder if you have any tips on where is best to collect it. thanks

Edited November 2, 2015 by Otodusobliquus

[Coco]

Hi,

Al Dente, it is a marvelous tooth, I never seen that before...

Coco

[MarcoSr]

Marco, I have been collecting and searching Aquia formation matrix recently and wonder if you have any tips on where is best to collect it. thanks

Talking the matrix directly from the Aquia Formation is difficult for lots of reasons. You need owner permission to dig in the Cliffs which would require federal and state permits for federal and state land or private owner permission for private land. In most spots the Aquia Formation is very hard unless extremely weathered which makes getting the matrix out extremely difficult. Also unless you know where the zone contacts are, the tooth density is really low in the matrix. Even at the contacts, the density is good at best. The matrix for this post was taken from private property in VA with owner permission where the matrix is right at the surface and much softer than normal because of surface water. The owner had water right near the Formation so we could use hoses to wash the matrix down to shells and fossils at the site. This really helped to concentrate the fossils. Even with this site washing and a washing at home the matrix only had a good fossil density. This owner gives me access because of my work with the vertebrate studies of different VA formations and doesn’t permit others to collect the property.

If you do want to get at the formation itself the best way to do that is from slides on the beach or cliff sluff in the early spring on the beach. Matrix in the slides is still usually fairly hard so it is difficult to sift and fossil density is very low. Freeze/thaw cliff sluff in the spring (up to several inches of the cliff face) is fairly soft and easy to sift but the fossil density is very low. However the preservation quality of the specimens found in the sluff makes the effort sometimes very worthwhile. A good place to get at good spring sluff material is at the end of the BLM trail which comes out on the Potomac River in MD below Liverpool Point. Turn left at the Potomac River and take the sluff at the beginning of the long set of cliffs. This matrix is Aquia Formation zone 2. If you want Aquia Formation zone 4 from slides go to the end of the Purse State Park trail in MD which comes out on the Potomac River. Turn left at the Potomac River and walk all the way past the Point with the small stream outlet. The slides closest to the Point, once past it, will have the better matrix. However if you don’t recognize the zone contacts you won’t find many teeth at all in the matrix. Zone 4 has a much lower fossil density than zone 2 unless you are at the contacts with zone 3 and/or zone 5.

If you want a much higher fossil density you need to take fine/small gravel from the beach or shell hash from the beach. The Potomac River has washed the matrix down for you. The condition of the teeth in the gravel is really hit and miss with a lot of water worn/damaged teeth but you can find pristine specimens as well. The shell hash usually has better tooth quality, less water worn teeth, but usually has a lower fossil density and not the same tooth species diversity as the gravel. Of all the spots that I’ve taken home gravel or shell hash the best spot for tooth density, quality and species diversity is the spot to the left at the beginning of the long set of cliffs where the BLM trial comes out on the Potomac River. Take the shell hash as close to the cliffs as possible. Take the gravel at the water’s edge. Tooth quality is the best in the spring as the Potomac River washes down the fresh cliff sluff from the freeze/thaw of the winter. A lot of taking matrix is trial and error and learning where the best spots are.

If you use window screen to wash your matrix in the Potomac River or at home you will lose some of the very small species. A .4mm sieve will catch the very small shark and ray teeth. However it will clog up very easily and isn’t very time efficient to use in the field. I use a 1mm sieve in the field for the Aquia Formation specimens which doesn’t clog as easily and captures the larger of the very small species of shark and ray specimens. I always wash my matrix in the Potomac River to cut down on the volume and weight of the matrix that I then back pack out.

Marco Sr.

[Otodusobliquus]

Thanks for the advice, I have been collecting beach material from what seems to me a very good site. There is very little wave action which means the teeth are typically in good condition, and due to the lack of Pleistocene gravel deposits, the beach is made entirely from Aquia formation material. Any matrix collected is made entirely from shells, the rest of the beach being fine silt or sand.

[MarcoSr]

Thanks for the advice, I have been collecting beach material from what seems to me a very good site. There is very little wave action which means the teeth are typically in good condition, and due to the lack of Pleistocene gravel deposits, the beach is made entirely from Aquia formation material. Any matrix collected is made entirely from shells, the rest of the beach being fine silt or sand.

I try to take Aquia matrix from as many sites as I can to improve my chances of finding something new. Some sites only have zone 2. Some are mostly zone 4. Some land sites have zone 6/7. You get slightly different species from the different zones. I really prefer high quality teeth so your spot sounds like a good one.

Marco Sr.

[Otodusobliquus]

They aren't too high quality, but way better than the ones I found at purse the one time I brought gravel out. See my gallery, I would appreciate some id help on many of the teeth. I think the zone washing out at my site is zone two. The Aquia formation is currently my favorite formation to hunt, such a wide variety of things to find. I currently use window screen to sift my micro matrix. Where can I find a smaller size? By the way, your micro collection is awesome. I have read every thread listed on your post showing the micro fossil threads you have on the forum.

[MarcoSr]

They aren't too high quality, but way better than the ones I found at purse the one time I brought gravel out. See my gallery, I would appreciate some id help on many of the teeth. I think the zone washing out at my site is zone two. The Aquia formation is currently my favorite formation to hunt, such a wide variety of things to find. I currently use window screen to sift my micro matrix. Where can I find a smaller size? By the way, your micro collection is awesome. I have read every thread listed on your post showing the micro fossil threads you have on the forum.

I never found a good spot in Purse State Park where the gravel contained worthwhile micros. There were slides as I mentioned above that did contain matrix with worthwhile micros. However, as stated above, there is gravel worth taking out along the Potomac River along the BLM property.

If you are finding Paraorthacodus clarkii and/or Palaeocarcharodon orientalis, there is zone 2 where you are collecting.

Individual teeth can be very difficult to id from pictures unless the teeth have unique features which are clearly visible in the pictures. Elasmo.com in its pages on the Aquia Formation fauna is a really good website for id help.

I posted micro specimens here on TFF from some of the matrix from different sites that I search to try to peak the interest of other TFF members in micros. I'm glad you have looked at my TFF threads on micros. It makes the time to take the pictures and post on TFF worthwhile. I have micros in my collection from matrix from at least 150 sites worldwide.

You can buy scientific sieves on-line at sites like e-bay but they are very expensive. I use 12" diameter fine flour sieves that I also get from e-bay for the field which are much cheaper like the one below. I just attach the sieve to my backpack.

http://www.ebay.com/itm/12-Stainless-Steel-Rim-Sieve-/252151903837?hash=item3ab56cb65d:g:GSIAAOSwAYtWNVyS

Marco Sr.

Edited November 2, 2015 by MarcoSr

[ynot]

I posted micro specimens here on TFF from some of the matrix from different sites that I search to try to peak the interest of other TFF members in micros. I'm glad you have looked at my TFF threads on micros. It makes the time to take the pictures and post on TFF worthwhile. I have micros in my collection from matrix from at least 150 sites worldwide.

Marco Sr.

Thank You for doing all that work on the micros-- a wonderful resource that is very much appreciated !!

Wow -- 150 sites -- that is truly amazing!!

Tony

[MarcoSr]

Thank You for doing all that work on the micros-- a wonderful resource that is very much appreciated !!

Wow -- 150 sites -- that is truly amazing!!

Tony

Tony

Thank you for the kind words. They are appreciated. I've looked for micros for a while but have concentrated on them for the last 10 years or so. I especially like helping with the vertebrate studies of different formations in MD/VA. The only drawback is I donate all of the study specimens that I find which is one reason that I started taking pictures so I would at least have the pictures.

Marco Sr.

[Castle Rock]

Marco, I have collected Aquia Fm. material in Maryland, near Fort Washington Park. I no longer live in the DC area and don't get back there much from Texas. Could you provide some more detail about zonation in the Aquia? I would like to know more about the topic. THANKS! Dave in Midland, Texas

[MarcoSr]

Marco, I have collected Aquia Fm. material in Maryland, near Fort Washington Park. I no longer live in the DC area and don't get back there much from Texas. Could you provide some more detail about zonation in the Aquia? I would like to know more about the topic. THANKS! Dave in Midland, Texas

Latest thinking is the Piscataway Member of the Aquia Formation is divided into five zones, zones 1-5. Zone 1 has limited exposure in VA/MD and I've only found it on private property along a creek off of the Potomac River in one area in VA. Zone 2 is the zone mostly collected in MD along the Potomac River especially along BLM property below Liverpool Point but is also exposed on the VA side but unless you have a boat or private access it is tough to get to on the VA side of the Potomac River. Zone 3 is a indurated ledge which isn't collected. Zone 4 also is exposed on both sides of the Potomac River but easily accessed through Purse State Park on the MD side of the Potomac River. Zone 5 is another ledge that isn't collected.

The Paspotansa Member of of the Aquia Formation has zones 6-9. I haven't collected the Paspotansa Member much at all. I have collected Zones 6/7 at land sites in both MD/VA. I have not found/collected zones 8/9.

Although a lot of the shark, ray and fish species are found throughout the Aquia zones, some species are more common in certain zones than others. There are a number of species only found in zone 2. A number of species that are rare in zone 2 become more abundant in the latter zones etc. The Piscataway Member was more near shore and the Paspotansa Member was more offshore. There are a great number of micro shark and ray teeth in the Aquia Formation that most collectors don't see because they only surface collect. Some of these micro teeth can be found crawling the beach on hands and knees but bulk collecting in the right spots is much more efficient.

Marco Sr.

[Castle Rock]

Marco, would you be prepared to offer your opinion as to which of these Zones I would have been collecting in, Just north of the small marina on Piscataway Creek? ALSO, could you possibly direct interested readers to online publications that address the zonation that you have referred to? THANK YOU! Dave

[Auspex]

Here is some older information; I would be surprised if some of it wasn't updated since, but it should still be useful:

LINK

[MarcoSr]

Here is some older information; I would be surprised if some of it wasn't updated since, but it should still be useful:

LINK

Chas

The older publications all called the Aquia Formation Eocene versus Paleocene. That is at least one thing that has been corrected in the more recent publications.

Marco Sr.

[MarcoSr]

Marco, would you be prepared to offer your opinion as to which of these Zones I would have been collecting in, Just north of the small marina on Piscataway Creek? ALSO, could you possibly direct interested readers to online publications that address the zonation that you have referred to? THANK YOU! Dave

No, that area has a mingling of Paleocene, Eocene and Miocene in the different ravines and stream beds north of Piscataway Creek. I never collected along Piscataway Creek itself but collected the land sites all around it. When I collected there, it was very difficult to be sure of what formation/member I was collecting especially if I was collecting float material versus material directly from a formation. I found Miocene, Eocene and Paleocene specimens in float in the stream beds and ravines because of the rolling nature of the terrain and the depth of some of the ravines.

Not much has been written on the zones especially recently. The best overview of the zones with references to papers is on elasmo.com under "FAUNAS" and then "AQUIA".

Marco Sr.

[Castle Rock]

THANK YOU Marco for the most interesting information on the Aquia! Dave