Early Ammonoids

Hajar

Haliphron Atlanticus
Registered
Joined
Mar 7, 2009
Messages
540
#3
Another early ammonoid in pyrite from the German Devonian (17 mm across). Does anybody recognise this? Could it be Erbenoceras?
 

Attachments

Hajar

Haliphron Atlanticus
Registered
Joined
Mar 7, 2009
Messages
540
#5
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.
 

Hajar

Haliphron Atlanticus
Registered
Joined
Mar 7, 2009
Messages
540
#8
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.
 

Attachments

Hajar

Haliphron Atlanticus
Registered
Joined
Mar 7, 2009
Messages
540
#9
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.
 

Attachments

Hajar

Haliphron Atlanticus
Registered
Joined
Mar 7, 2009
Messages
540
#11
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.
 

Attachments

Terri

Sepia elegans
Registered
Joined
Dec 20, 2009
Messages
961
#16
Hello Hajar! It's great to see you back, I have learned so much from your posts, hope you stick around!:smile:
 

Hajar

Haliphron Atlanticus
Registered
Joined
Mar 7, 2009
Messages
540
#17
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.
 

Terri

Sepia elegans
Registered
Joined
Dec 20, 2009
Messages
961
#18
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!
 

Hajar

Haliphron Atlanticus
Registered
Joined
Mar 7, 2009
Messages
540
#19
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.
 

Attachments

DWhatley

Certified Ceph Head For Life
Staff member
Moderator
Joined
Sep 4, 2006
Messages
20,145
Location
Gainesville, GA
#20
It would be very interesting to see what that "rams horn" looking (Erbenoceras) animal would have looked like!
 

Members online

Forum statistics

Threads
19,325
Messages
201,729
Members
8,252
Latest member
RSG

Monty Awards

TONMOCON IV (2011): Terri
TONMOCON V (2013): Jean
TONMOCON VI (2015): Taollan
TONMOCON VII (2018): ekocak

About the Monty Awards
Top