Early Ammonoids

Discussion in 'Cephalopod Fossils' started by Hajar, Nov 3, 2009.

  1. Hajar

    Hajar Haliphron Atlanticus Registered

    Joined:
    Mar 7, 2009
    Messages:
    540
    Likes Received:
    60
    Here's a real Bactrites from the German Devonian (Büdesheim, Eifel), just 16 mm long, but beautifully preserved in pyrite. The ventral lobe on the sutures is nicely seen on this specimen.
     

    Attached Files:

  2. Hajar

    Hajar Haliphron Atlanticus Registered

    Joined:
    Mar 7, 2009
    Messages:
    540
    Likes Received:
    60
    and this is an Anetoceras, 44 mm across, from the Early Devonian of Bundenbach.
     

    Attached Files:

  3. Hajar

    Hajar Haliphron Atlanticus Registered

    Joined:
    Mar 7, 2009
    Messages:
    540
    Likes Received:
    60
    Another early ammonoid in pyrite from the German Devonian (17 mm across). Does anybody recognise this? Could it be Erbenoceras?
     

    Attached Files:

  4. Architeuthoceras

    Architeuthoceras Architeuthis Staff Member Moderator

    Joined:
    Nov 19, 2002
    Messages:
    2,391
    Likes Received:
    94
    Location:
    somewhere under the desert sky
    Beautiful fossils Hajar, can you see the lobes on the "Erbenoceras", it sure looks like a nautiloid. :heee:

    (I guess its just about as close as an ammonoid can get to a nautiloid :sly:)
     
  5. Hajar

    Hajar Haliphron Atlanticus Registered

    Joined:
    Mar 7, 2009
    Messages:
    540
    Likes Received:
    60
    Thanks Kevin. Yes, this one has the ventral lobe, very much like the Bactrites. Otherwise the suture is very simple. I'll take another photo tomorrow.
     
  6. Hajar

    Hajar Haliphron Atlanticus Registered

    Joined:
    Mar 7, 2009
    Messages:
    540
    Likes Received:
    60
    Close-ups as promised.
     

    Attached Files:

  7. Hajar

    Hajar Haliphron Atlanticus Registered

    Joined:
    Mar 7, 2009
    Messages:
    540
    Likes Received:
    60
  8. Hajar

    Hajar Haliphron Atlanticus Registered

    Joined:
    Mar 7, 2009
    Messages:
    540
    Likes Received:
    60
    Dr. Christian Klug identifies the specimen above as Gyroceratites and the Anetoceras is now renamed to Ivoites hunsrueckianum or perhaps Bovites. Thanks!

    The phylogram below is from DE BAETS, K., KLUG, C. & KORN, D. (2009): Anetoceratinae (Ammonoidea, Early Devonian) from
    the Eifel and Harz Mountains (Germany), with a revision of their genera. – N. Jb. Geol. Paläont. Abh., 252: 361–376.
     

    Attached Files:

  9. Hajar

    Hajar Haliphron Atlanticus Registered

    Joined:
    Mar 7, 2009
    Messages:
    540
    Likes Received:
    60
    Here's a fine image to illustrate the "Devonian Nekton Revolution" in which the early ammonoids play a major role. It's from a new paper by Klug et al. (2009) and has the caption "Macroecological steps in the evolution of Palaeozoic marine food webs".

    Klug, C., Kroger, B., Kiessling, W., Mullins, G.L., Servais, T., Fryda, J., Korn, D. & Turner, S. 2009: The Devonian nekton revolution. Lethaia, 10.
     

    Attached Files:

  10. Architeuthoceras

    Architeuthoceras Architeuthis Staff Member Moderator

    Joined:
    Nov 19, 2002
    Messages:
    2,391
    Likes Received:
    94
    Location:
    somewhere under the desert sky
    Thanks for posting that illustration Hajar, it's great. Do they consider the early nautiloids as macro-plankton until they developed tightly coiled shells, then they became nectonic? Any idea which one of the authors is the artist?
     
  11. Hajar

    Hajar Haliphron Atlanticus Registered

    Joined:
    Mar 7, 2009
    Messages:
    540
    Likes Received:
    60
    Hi Kevin,

    This is what they say about early nautiloids:
    “Among the nautiloids, all nautiloids originating during the Cambrian, the Actinocerida, Ascocerida, Discosorida, Ellesmerocerida, Endocerida, Lituitida and Oncocerida are here considered demersal; this inference is based on the facies they occur in and morphological features such as coiling and position of hyponomic sinuses (Chen & Teichert 1983; Stridsberg 1985; Westermann 1999; Kroger & Mutvei 2005).”

    On orthocerids: “Most orthocerids were probably capable of minor horizontal movements but they were ineffective swimmers and migrated predominantly vertically and/or drifted passively (Hewitt & Watkins 1980; Westermann 1999; Mutvei 2002; Kroger 2003, 2005; Kroger & Mutvei 2005; Mutvei et al. 2007). This is suggested by their poorly differentiated muscle-attachment structures, the absence of significant endosiphonal or endocameral deposits and, in some cases, also shell morphology.”

    “The coiled Tarphycerida and Nautilida are interpreted as nektobenthic or nektoplanktonic based on actualistic comparision of the shell form, muscle attachment structures and position of the hyponome (Westermann 1999; Kroger & Mutvei 2005).”

    Here below is how they assigned the different animal groups to "ecological megaguilds".

    Don't know who the artist is, but I've asked.
     

    Attached Files:

  12. Hajar

    Hajar Haliphron Atlanticus Registered

    Joined:
    Mar 7, 2009
    Messages:
    540
    Likes Received:
    60
    Christian Klug is the artist. I'm very impressed.
     
  13. Architeuthoceras

    Architeuthoceras Architeuthis Staff Member Moderator

    Joined:
    Nov 19, 2002
    Messages:
    2,391
    Likes Received:
    94
    Location:
    somewhere under the desert sky
    Thanks again Hajar :smile:

    It seems to mostly match what I find around here, except that I find Tarphycerids alongside Endocerids in a few locations.
     
  14. Architeuthoceras

    Architeuthoceras Architeuthis Staff Member Moderator

    Joined:
    Nov 19, 2002
    Messages:
    2,391
    Likes Received:
    94
    Location:
    somewhere under the desert sky
    Yes! a very good artist :notworth:

    Maybe he will do one for Dieter and Alan on their Chainman Goniatites Zone paper :sly:
     
  15. Hajar

    Hajar Haliphron Atlanticus Registered

    Joined:
    Mar 7, 2009
    Messages:
    540
    Likes Received:
    60
    I like this Early Devonian Borivites from the abstract book for the Dijon meeting linked to by Kevin.
     

    Attached Files:

  16. Terri

    Terri Sepia elegans Registered

    Joined:
    Dec 20, 2009
    Messages:
    960
    Likes Received:
    85
    Hello Hajar! It's great to see you back, I have learned so much from your posts, hope you stick around!:smile:
     
  17. Hajar

    Hajar Haliphron Atlanticus Registered

    Joined:
    Mar 7, 2009
    Messages:
    540
    Likes Received:
    60
    Why thank you Terri! I've been travelling and spending a lot of time in the sea and even set up a marine aquarium, but decided not to keep cephalopods in there. It will soon be cool enough to go out into the field here and I'll be back looking at the rocks.
     
  18. Terri

    Terri Sepia elegans Registered

    Joined:
    Dec 20, 2009
    Messages:
    960
    Likes Received:
    85
    Your welcome, we have had 100+ heat indexes for most of this summer with a lot of rain, which has caused the undergrowth to go wild. Even if I could handle the heat I would have to use a machete to even find an outcrop. But on the bright side the weather is starting to cool off here also!
     
  19. Hajar

    Hajar Haliphron Atlanticus Registered

    Joined:
    Mar 7, 2009
    Messages:
    540
    Likes Received:
    60
    Here's a pile of Devonian ammonoids from Morocco thrown together on my desk. There's Erbenoceras (13 cm at back), Platyclymenia, Gonioclymenia, Cosmoclymenia, Gyroceratites, Agoniatites, Sellanarcestes, Protornoceras, and Acrimenoceras.
     

    Attached Files:

  20. DWhatley

    DWhatley Cthulhu Staff Member Moderator

    Joined:
    Sep 4, 2006
    Messages:
    19,078
    Likes Received:
    1,123
    Location:
    Gainesville, GA USA
    It would be very interesting to see what that "rams horn" looking (Erbenoceras) animal would have looked like!
     

Share This Page