Virginia Miocene/Pliocene Shells

[historianmichael]

Last month I collected fossil shells at several exposures in Virginia of the Late Miocene Eastover Formation (Cobham Bay Member) and Early Pliocene Yorktown Formation (Sunken Meadow Member). While my intention was to focus on the larger fossils, when I got home and started to clean my finds, I thought it would be cool to screen the excess debris and see what else I had found. Although I ended up finding a lot of tiny shells and shell fragments, they require a microscope to see and the fine details have made identification challenging. I have consulted several publications on these formations and yet I am a bit stumped on these last ten fossils. Any help further narrowing these down would be greatly appreciated! 

 

Eastover Formation

#1

 

 

#2- Gari sp.?

  

 

 

#3- Nucula sp.?

  

 

Yorktown Formation 
#4

 

 

#5

 

 

#6- Chama congregata?

 

 

#7- Chama congregata?

 

 

 

#8

 

 

#9

 

#10

 

[ClearLake]

I'll give the Yorktown ones a shot until one of the experts like @MikeR @sixgill pete or @Al Dente chime in with the correct answers.  My names all come from Campbells 1993 Virginia Publication 127.

4.  That's a nice little shell.  Check out Boreotrophon tetricus as it seems to fit as best I can tell from your picture 

5.  Looks like one of the pectens, but not sure how far you'll get with an ID since its looks quite eroded

6.  Chama (and probably C. congregata due to the clockwise coiling)

7.  Chama (and probably C. congregata due to the clockwise coiling)

8.  This one is tough as it looks very juvenile and is a little beat up and I can't clearly see the aperture, but it is one of the Muricidaes, maybe look at Coralliophila leonensis (I guess that one is not technically in Muricidae, but it is similar)

9.  Seems like this might be a protoconch of a Busycon.  There are a couple of species from the Yorktown but none that I found show a good picture of this small of a specimen.  

10.  Not real sure, but perhaps one of the Eucrassatella species, especially if it feels heavy/thick for its size.

 

Hope this helps at least a bit.

[hemipristis]

#1 Imperial venus Chione (Lirophora) latilirata?

[historianmichael]

Thank you both for your initial thoughts!

 

@ClearLake I had too thought that #4 looks like Boreotrophon tetricus, but I was a little thrown off by the lack of a long siphonal canal. I had found another Boreotrophon tetricus and #4 looks a little different. Here is a photo of that shell:

 

 

 

I am not sure that #5 is a pecten. This shell is more arced and resembles more of a clam than a scallop. It looked a little like an ark clam but I wasn't too confident in that.

 

@hemipristis Lirophora is a possibility, but I wasn't too sure since the ribs on this shell are not as prominent as one typically sees on Lirophora. 

[ClearLake]

21 hours ago, historianmichael said:

lack of a long siphonal canal

My assumption is that it is just broken off.  You have the specimen in hand, maybe you can tell if that is true or not.  Is the one you posted for ID a lot smaller than this other one you found?  If so, compare them side by side and see if the small one looks similar to the earliest whorls on the bigger one.  There are some species that look quite different in their youngest stages.

 

21 hours ago, historianmichael said:

It looked a little like an ark clam

An ark clam should have the taxodont dentition (many small teeth) and I do not see that on your shell.  It looks to me like the remains of broken auricles at the hinge area, but maybe I'm misinterpreting what I see.  Also remember, that in pectens, one valve is often much more inflated that the other.  Just what I was thinking.

 

[sixgill pete]

I will try to take some time shortly to review these. I use the same reference as @ClearLake along with the NCFC mollusk publication and the Lee Creek paper from the Smithsonian contributions to paleobiology.

[MikeR]

1.  At first I thought Parvilucina but the hinge is wrong.  Maybe Astarte.

2.  Tellinidae

3.  Nucula

4.  Boreotrophon tetricus

5.  Clinocardium probably C. acutilaqueatum

6. & 7.  Chama congregata

8. & 9.  Immature Neogastropoda in either family Buccinidae or Fasciolariidae.

10.  Immature Eucrasatella virginica

[historianmichael]

Thank you again @MikeR for your help. Your knowledge on Cenozoic mollusks is incredible!