Jump to content
  • Crassinella Clam


    Images:

    I_gotta_rock
    • Collected from matrix deposited in the Chesapeake Bay by landslide. Donated to the Delaware Museum of Natural History.

    Taxonomy

    Crassinella Clam

    Kingdom: Animalia
    Phylum: Mollusca
    Class: Bivalva
    Order: Carditoida
    Family: Crassatellidae
    Genus: Marvacrassatella
    Species: M. turgidula
    Author Citation (Conrad, 1843)

    Geological Time Scale

    Eon: Phanerozoic
    Era: Cenozoic
    Period: Neogene
    Epoch: Miocene

    Stratigraphy

    Choptank Formation
    Drum Cliff Member

    Biostratigraphy

    Shattuck Zone 17

    Provenance

    Collector: Heather Siple
    Date Collected: 07/03/2017
    Acquired by: Field Collection

    Dimensions

    Blank: 50mm
    Width: 65mm
    Height: 15mm

    Location

    St Leonard
    Calvert County
    Maryland
    United States

    Comments

    Collected from matrix deposited in the Chesapeake Bay by landslide. Donated to the Delaware Museum of Natural History.



    User Feedback


    I_gotta_rock

    Posted · Report

    29 minutes ago, UtahFossilHunter said:

    Is that a predation hole I see?

    No doubt about it. The predatory snails were all over the place there then -- moon snails, Ecphoras and a few other drillers. The beach is littered with shells with conspicuously round holes. There are even predatory holes (not all the way through, though) in 1-inch thick Isognomon shells!

    Share this comment


    Link to comment
    Share on other sites
    Fossil-Hound

    Posted · Report

    @I_gotta_rock I had a candid discussion with @SailingAlongToo about Ecphora predation and there is no hard evidence that Ecphora produced these holes. It's a theory. The difficult part about the proof is the Ecphoras interior did not preserve in the fossil record but the theory is that Ecphora where similar to modern Conch snails and fed upon bivalves such as Chesapecten and Gastropoda such as Turitella. Dr. L. Ward may be able to shed some light on this discussion.

    Share this comment


    Link to comment
    Share on other sites
    Fossil-Hound

    Posted · Report

    On 9/8/2017 at 0:18 PM, I_gotta_rock said:

    That still leaves the moon snails, which were and still are predators.

    Yes modern Naticidae's are predatory but the real question is did they start out that way during the Miocene or further back to the Triassic? This goes back to a similar argument that some trilobites where carnivorous, but started out as herbivores. The fascinating thing about micro-evolution is that it's always in motion. Perhaps moon snails started out as herbivores but during the competition for food, they adapted themselves to develop mouth pieces to go on the offensive and became carnivorous. That's an interesting theory to consider. The two big gastropod families at play here are the Muricidae (Ecphora etc.) and Naticidae (Moon Snail etc.). I found this interesting article (attached it for long term archival):

     

    http://www.calvertmarinemuseum.com/DocumentCenter/View/630

     

    Pg. 16 from Kelley reads:

     

    Despite intensive study, we do not understand fully all the factors that influence drilling predation and in turn its effect on evolution. Ongoing work is examining spatial variation in drilling; the relationship between predation intensity and diversity, and between predation and degree of escalation of faunas; the effect of multiple predators on predation intensities; and whether different species of predators can be discriminated by the holes they drill. The Miocene faunas of Maryland will continue to play a key role in such work.

     

    ------

    What we do know is this:

     

    * Modern Naticidae gastropods do prey on mollusks and other gastropods.

    * Ecphora's are extinct hence we don't have any hard evidence of Ecphora predation though this shouldn't be ruled out. What's interesting to note is that Ecphora's are from the family of Muricidae and this family is composed of predatory Gastropods so it wouldn't surprise me if Ecphora were predatory, we just don't have any hard evidence of said predation.

     

    In conclusion Miocene moon snails may have been herbivores and then evolved into carnivores or omnivores sometime after the Triassic so perhaps they were already carnivorous by the Miocene of the eastern USA (which at the time would have been underwater).

     

    CMM_Paleontology_Symposium%2C_2006_201410081226238850.pdf

    Share this comment


    Link to comment
    Share on other sites


    Create an account or sign in to comment

    You need to be a member in order to leave a comment

    Create an account

    Sign up for a new account in our community. It's easy!

    Register a new account

    Sign in

    Already have an account? Sign in here.

    Sign In Now


×